Publications by authors named "Daniel Buser"

193 Publications

Long-term effectiveness of 6 mm micro-rough implants in various indications: A 4.6- to 18.2-year retrospective study.

Clin Oral Implants Res 2021 Jun 15. Epub 2021 Jun 15.

Department of Oral Surgery & Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Objectives: To evaluate the long-term effectiveness of 6 mm implants in various indications with a micro-rough surface after 4.6-18.2 years in function and to assess key factors associated with implant survival, success, and biologic/technical complications.

Materials And Methods: Fifty-five patients with seventy-four 6 mm implants placed from 2000 to 2013 attended the re-examination assessing well-established clinical and radiographic parameters, biologic and prosthetic complications, and patient-reported outcome measures.

Results: Five implants were lost after a mean follow-up period of 9.1 years resulting in a survival rate of 93.2%. All losses occurred in free-end situations in the mandible. Smoking habit significantly reduced implant survival (hazard ratio 36.25). Two implants exhibited a history of peri-implantitis, and one implant showed progressive marginal bone loss (MBL) resulting in a success rate of 89.2%. The mean MBL amounted to 0.029 mm. Increased MBL was found for implants placed in the maxilla (0.057 mm) and for implants with a diameter of 4.1 mm (0.043 mm). Soft tissue thickness (1.39 mm) and width of keratinized mucosa (1.91 mm) had no effect on MBL. Patient-reported outcome measures showed high satisfaction (mean VAS scores 88%) and high quality of life (mean OHIP-G14 score 2.2).

Conclusion: The present study demonstrated survival and success rates of 93.2% and 89.2% for 6 mm implants used in various indications. A factor leading to higher implant failure was smoking, whereas modulating factors increasing annual MBL included implants placed in the maxilla and implants with a diameter of 4.1 mm compared to 4.8 mm.
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http://dx.doi.org/10.1111/clr.13795DOI Listing
June 2021

Vertical eruption of anterior maxillary teeth adjacent to single-implant-supported crowns: An assessment after a 3-year follow-up period.

J Prosthet Dent 2021 Mar 4. Epub 2021 Mar 4.

Full Professor, Department of Oral Implantology and Prosthetic Dentistry, ACTA, University of Amsterdam and VU University, Amsterdam, the Netherlands.

Statement Of Problem: Vertical eruption of teeth adjacent to an implant has been reported clinically and might affect the esthetic outcome over time. The prevalence of the problem is unclear.

Purpose: The purpose of this prospective clinical trial was to evaluate the vertical eruption of anterior maxillary teeth adjacent to single-implant crowns after a 3-year follow-up period.

Material And Methods: Thirty single dental implants were inserted in maxillary anterior sites including the first premolar. The mean age of the participants at implant-supported crown insertion was 48.4 years (range 23 to 79 years). Each implant was restored with a 1-piece screw-retained ceramic single crown. The vertical changes of 60 adjacent anterior maxillary teeth were evaluated from periapical radiographs and casts at baseline, 6, 12, and 36 months.

Results: A global ANOVA test showed statistically significant differences for the outcomes of the distance-implant platform and cement-enamel junction (DPC) (P<.001), crown length distal (P=.021) and mesial (P=.035), implant crown length (P=.022), and incisal edge to edge (P<.001).

Conclusions: Continuous vertical tooth eruption next to a single dental implant was observed in adult participants.
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http://dx.doi.org/10.1016/j.prosdent.2020.07.040DOI Listing
March 2021

Early Loading of Titanium Dental Implants with an Intraoperatively Conditioned Hydrophilic Implant Surface: 3-Year Results of a Prospective Case Series Study.

Int J Oral Maxillofac Implants 2020 Sep/Oct;35(5):1013-1020

Purpose: The hydrophilic implant surface (INICELL) is a chemical alteration of a sandblasted and thermally acid-etched surface that should lead to long-term osseointegration. This study investigated 3-year results after early loading of implants with a hydrophilic, moderately rough surface in occlusal contact.

Materials And Methods: This prospective case series study was conducted in subjects with partially edentulous mandibles. Implants were placed on day 21 and loaded with a provisional reconstruction after at least 21 days of healing (baseline, day 0) if their implant stability quotient (ISQ) was ≥ 70 (mean of three measurements) and were replaced by definitive porcelain-fused-to-metal prostheses at the 6-month follow-up visit. Follow-up examinations were planned 1, 3, 6, 12, and 36 months after baseline.

Results: A total of 20 implants were placed in 15 patients (mean age: 51 years, range: 32 to 67 years). After 36 months, all implants were osseointegrated, and no suppuration was recorded. Small changes of bone level were observed between 3 months and 36 months. At 36 months, the median values of the 20 implants were 0.25 (range: 0 to 0.5, SD: 0.17), 0.25 (range: 0 to 1, SD: 0.27), and 4 (range: 2 to 7.25, SD: 1.17) for the mean modified Plaque Index (mPI), mean modified Sulcus Bleeding Index (mSBI), and mean probing pocket depth, respectively. The pairwise analysis between 3 and 36 months showed an improvement in the mean mPI (P = .0126) and mean mSBI (P = .0059). After 36 months, all patients (n = 15) were fully satisfied with a mean of 9.43 (range: 8 to 10, SD: 0.678) at the visual analog scale.

Conclusion: Early functional loading of implants with a hydrophilic, moderately rough outer surface in occlusal contact 21 days after healing appears to be a safe and feasible treatment option when placed in the posterior mandible of partially edentulous patients.
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http://dx.doi.org/10.11607/jomi.8045DOI Listing
October 2020

Microbial and host-derived biomarker changes during ligature-induced and spontaneous peri-implantitis in the Beagle dog.

J Periodontal Res 2021 Jan 3;56(1):93-100. Epub 2020 Sep 3.

Department of Periodontology, University of Bern, Bern, Switzerland.

Objective: To evaluate microbial and host-derived biomarker changes during experimental peri-implantitis in the Beagle dog.

Background: Limited data exist on the microbial and biomarker changes during progressive bone loss as result of experimental peri-implantitis.

Methods: In total, 36 implants (n  = 6) were assessed over 3 episodes of ligature-induced peri-implantitis followed by a period of spontaneous progression. Implants with hybrid (H) and completely rough (R) surface designs were used. Clinical and radiographic parameters were recorded at 4 timepoints. Peri-implant sulcus fluid was collected from the buccal and lingual aspects of the implants. The presence of 7 bacterial species and 2 host-derived biomarkers was assessed during the study period.

Results: Total bacterial counts were significantly correlated with marginal bone loss (MBL) (r = .21; P = .009). Further, Phorphyromonas gulae (Pg) and Tannerella forsythia (Tf) were commonly correlated with MBL, suppuration (SUP) and the sulcular bleeding index scores (mSBI) (P < .05). Other bacteria were further correlated with SUP, mSBI, and MBL. While the analyzed bacteria dropped, Prevotella intermedia (Pi) further increased during the spontaneous progressive phase (P < .05). Total bacterial load did not differ significantly between H and R implants. Host-derived IL-10 was undetected along the study period. IL-1β positively correlated with probing pocket depth (r = .18; P = .03). During spontaneous progression, H implants displayed statistically significant lower levels of IL-1β (P = .003).

Conclusion: Experimental peri-implantitis is associated with an increase in bacterial counts. While Pg and Tf are associated with ligature-induced disease progression, Pi augmented its load during the spontaneous progressive phase. IL-1β is associated with pocket probing depth and influenced by implant surface characteristics during the spontaneous progression phase.
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http://dx.doi.org/10.1111/jre.12797DOI Listing
January 2021

Cellular responses to deproteinized bovine bone mineral biofunctionalized with bone-conditioned medium.

Clin Oral Investig 2021 Apr 1;25(4):2159-2173. Epub 2020 Sep 1.

Laboratory of Oral Cell Biology, Dental Research Center, School of Dental Medicine, University of Bern, Freiburgstrasse 3, 3010, Bern, Switzerland.

Objectives: The aim of the study was to investigate whether the osteoinductive properties of bone-conditioned medium (BCM) harvested from cortical bone chips within a clinically relevant short-term period can enhance the biologic characteristics of deproteinized bovine bone mineral (DBBM) in vitro.

Materials And Methods: To assess the biofunctionalization of DBBM, the adhesive, proliferative, and differentiation properties of mesenchymal stromal ST2, pre-osteoblastic MC3T3-E1, and primary bone-derived cells grown on BCM-coated DBBM were examined by crystal violet staining of adherent cells, BrdU ELISA, and qRT-PCR, respectively.

Results: BCM extracted within 20 min or 24 h in either Ringer's solution (BCM-RS) or RS mixed with autologous serum (BCM-RS + S) increased the adhesive properties of all three cell types seeded on DBBM. The 20-min BCM-RS preparation appeared more potent than the 24-h preparation. BCM-RS made within 20 min or 24 h had strong pro-proliferative effects on all cell types grown on DBBM. RS + S alone exhibited a considerable pro-proliferative effect, suggesting an impact of the serum on cellular growth. DBBM coated with BCM-RS or BCM-RS + S, made within 20 min or 24 h each, caused a significant induction of osteogenic differentiation marker expression with a higher potency of the BCM-RS + S. Finally, a strong additive effect of fresh bone chips combined with BCM-coated DBBM on the osteogenic differentiation of the three cell types was observed.

Conclusions: Altogether, the data strongly support the biofunctionalization of DBBM with BCM extracted within a clinically relevant time window of 20 min.

Clinical Relevance: Pre-activation of non-osteoinductive biomaterials with BCM, prepared from autologous bone chips during a guided bone regeneration (GBR) procedure, bears the potential of an optimal treatment modality for bone defects in daily practice.
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http://dx.doi.org/10.1007/s00784-020-03528-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7966141PMC
April 2021

Investigating the Response of Human Neutrophils to Hydrophilic and Hydrophobic Micro-Rough Titanium Surfaces.

Materials (Basel) 2020 Aug 3;13(15). Epub 2020 Aug 3.

Department of Periodontics, Indiana University School of Dentistry, Indianapolis, IN 46202, USA.

Various treatments have been used to change both the topography and chemistry of titanium surfaces, aiming to enhance tissue response and reduce healing times of endosseous implants. Most studies to date focused on bone healing around dental implants occurring later during the healing cascade. However, the impact of the initial inflammatory response in the surgical wound site on the success and healing time of dental implants is crucial for implant integration and success, yet it is still poorly understood. The purpose of this study was to investigate the effect of titanium surface hydrophilicity on the response of human neutrophils by monitoring oxygen radical production, which was measured as chemiluminescence activity. Materials and Methods: Neutrophils were isolated from human donors' blood buffy coats using the double sucrose gradient method. Neutrophils were exposed to both hydrophilic and hydrophobic titanium surfaces with identical topographies in the presence and absence of human serum. This resulted in six experimental groups including two different implant surfaces, with and without exposure to human serum, and two control groups including an active control with cells alone and a passive control with no cells. Two samples from each group were fixed and analyzed by SEM. Comparisons between surface treatments for differences in chemiluminescence values were performed using analysis of variance ANOVA. Results and Conclusion: In the absence of exposure to serum, there was no significant difference noted between the reaction of neutrophils to hydrophilic and hydrophobic surfaces. However, there was a significant reduction in the mean and active chemiluminescence activity of neutrophils to serum-coated hydrophilic titanium surfaces than to serum-coated hydrophobic titanium surfaces. This suggests that surface hydrophilicity promotes enhanced adsorption of serum proteins, which leads to decreased provocation of initial immune cells and reduction of local oxygen radical production during wound healing. This can help explain the faster osseointegration demonstrated by hydrophilic titanium implants.
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http://dx.doi.org/10.3390/ma13153421DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7435731PMC
August 2020

Role of hyaluronan in regulating self-renewal and osteogenic differentiation of mesenchymal stromal cells and pre-osteoblasts.

Clin Oral Investig 2020 Nov 31;24(11):3923-3937. Epub 2020 Mar 31.

Department of Periodontology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, 3010, Bern, Switzerland.

Objectives: The aim of the study was to investigate the impact of two hyaluronan (HA) formulations on the osteogenic potential of osteoblast precursors.

Materials And Methods: Proliferation rates of HA-treated mesenchymal stromal ST2 and pre-osteoblastic MC3T3-E1 cells were determined by 5-bromo-20-deoxyuridine (BrdU) assay. Expression of genes encoding osteogenic differentiation markers, critical growth, and stemness factors as well as activation of downstream signaling pathways in the HA-treated cells were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunoblot techniques.

Results: The investigated HAs strongly stimulated the growth of the osteoprogenitor lines and enhanced the expression of genes encoding bone matrix proteins. However, expression of late osteogenic differentiation markers was significantly inhibited, accompanied by decreased bone morphogenetic protein (BMP) signaling. The expression of genes encoding transforming growth factor-β1 (TGF-β1) and fibroblast growth factor-1 (FGF-1) as well as the phosphorylation of the downstream signaling molecules Smad2 and Erk1/2 were enhanced upon HA treatment. We observed significant upregulation of the transcription factor Sox2 and its direct transcription targets and critical stemness genes, Yap1 and Bmi1, in HA-treated cells. Moreover, prominent targets of the canonical Wnt signaling pathway showed reduced expression, whereas inhibitors of the pathway were considerably upregulated. We detected decrease of active β-catenin levels in HA-treated cells due to β-catenin being phosphorylated and, thus, targeted for degradation.

Conclusions: HA strongly induces the growth of osteoprogenitors and maintains their stemness, thus potentially regulating the balance between self-renewal and differentiation during bone regeneration following reconstructive oral surgeries.

Clinical Relevance: Addition of HA to deficient bone or bony defects during implant or reconstructive periodontal surgeries may be a viable approach for expanding adult stem cells without losing their replicative and differentiation capabilities.
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http://dx.doi.org/10.1007/s00784-020-03259-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7544712PMC
November 2020

Cone beam computed tomography artefacts around dental implants with different materials influencing the detection of peri-implant bone defects.

Clin Oral Implants Res 2020 Jul 23;31(7):595-606. Epub 2020 Mar 23.

Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.

Objectives: To investigate the diagnostic accuracy of cone beam computed tomography (CBCT) for the diagnosis of peri-implant bone defects of titanium (Ti), zirconium dioxide (ZrO ) or titanium-zirconium (Ti-Zr) alloy implants.

Materials And Methods: Ti, Ti-Zr or ZrO implants with two diameters (3.3 mm, 4.1 mm) and one length (10 mm) were inserted in the angle of the mandible of six fresh defrosted pig jaws. Out of the 12 implants inserted, 6 served in the test group with standardized buccal peri-implant bone defects, whereas 6 served as control without bone defects. CBCTs were performed with three acquisition protocols (standard, high and low dose) using two devices. Four observers analysed CBCTs as follows: (a) presence of a peri-implant defect; (b) presence of peri-implant artefacts and impact on defect diagnosis; and (c) linear measurements of buccal peri-implant defect including height and width (in mm).

Results: CBCT device, CBCT settings, implant material, implant diameter and observer background did not significantly influence diagnostic accuracy. The sensitivity and specificity values were high for defect detection. ZrO led to a lower than average diagnostic accuracy (0.781). The linear measurements of peri-implant defect were underestimated by <1 mm on average. The subjective impact of artefacts on defect diagnosis was significantly affected by implant material and observer background.

Conclusions: CBCT showed high diagnostic accuracy for peri-implant bone defect detection regardless of the device, imaging setting or implant material used. If CBCT is indicated to assess peri-implant bone disease, low dose protocols could be a promising imaging modality.
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http://dx.doi.org/10.1111/clr.13596DOI Listing
July 2020

Clinical and esthetic outcomes of two different prosthetic workflows for implant-supported all-ceramic single crowns-3 year results of a randomized multicenter clinical trail.

Clin Oral Implants Res 2020 May 25;31(5):495-505. Epub 2020 Feb 25.

Department of Oral Implantology and Prosthetic Dentistry, ACTA, University of Amsterdam and VU University, Amsterdam, The Netherlands.

Objective: The aim of this randomized multicenter clinical trial was to evaluate and compare the performance of anterior all-ceramic implant crowns based either on prefabricated zirconia abutments veneered with pressed ceramics or on CAD/CAM zirconia abutments veneered with the hand build-up technique. The null hypothesis was that there is no statistically significant difference between the two study groups.

Material And Methods: Forty implants were inserted in sites 14-24 (World Dental Federation [FDI]) in two centers, the Universities of Bern and Geneva, Switzerland. Twenty patients each were randomized into either Group A and restored with one-piece single crown made of a prefabricated zirconia abutment with pressed ceramic, or Group B using an individualized CAD/CAM zirconia abutment with the hand-layered technique. After 3 years, clinical, esthetic, and radiographic parameters were assessed.

Results: Group A exhibited one dropout patient and one failure resulting in a survival rate of 89% after 3 years and two failures for Group B (90%). Clinical parameters presented healthy peri-implant soft tissues. Overall, no crestal bone level changes were observed (mean DIB of 0.13 mm [Group A] and 0.24 mm [Group B]). There were no significant differences at baseline, 6 months, and 1 and 3 years for DIB values between the two groups. PES and WES values evaluated at all three time points indicated stability over time for both groups and pleasing esthetic outcomes.

Conclusions: Both implant-supported prosthetic pathways represent a valuable treatment option for the restoration of implant crowns in the anterior maxilla.
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http://dx.doi.org/10.1111/clr.13586DOI Listing
May 2020

Sinus floor elevation or referral for further diagnosis and therapy: A comparison of maxillary sinus assessment by ENT specialists and dentists using cone beam computed tomography.

Clin Oral Implants Res 2020 May 12;31(5):463-475. Epub 2020 Feb 12.

Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China.

Objectives: To compare ear, nose, and throat (ENT) specialists and dentists assessing health or pathology of maxillary sinuses using cone beam computed tomography (CBCT).

Material And Methods: Two ENT specialists and two oral surgeons assessed 100 CBCT datasets of healthy patients referred for dental implant placement in the posterior maxilla and decided on the possibility of sinus floor elevation or the necessity for further diagnostic examinations based solely on radiographic findings. Inter-rater agreements within the same specialty were calculated with Cohen's kappa and overall agreements with Fleiss kappa, and factors influencing the decisions taken were evaluated using regression analyses.

Results: The correlation between all four raters was generally fair to moderate. The intra-specialty comparison showed a lower correlation between dentists than between ENT specialists. Absence of membrane thickening and total or subtotal sinus opacification showed the highest predictive value for a consensus in favor of sinus floor elevation and ENT referral, respectively. Flat membrane thickening with an irregular surface morphology was associated with disagreement between the examiners. Dome-shaped membrane thickenings were often considered as to be referred by dentists but not by ENTs.

Conclusion: The assessment of maxillary sinuses using CBCT imaging exhibited unsatisfactory agreement between ENT specialists and oral surgeons. Referral guidelines based on accidental CBCT findings that aim to diagnose relevant sinus pathologies early and avoid unnecessary diagnostics and/or therapies are needed, and an initial proposal for such recommendations is provided. Further research on correct interpretation of sinus findings and a validation of the present recommendations are required.
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http://dx.doi.org/10.1111/clr.13582DOI Listing
May 2020

The Critical Peri-implant Buccal Bone Wall Thickness Revisited: An Experimental Study in the Beagle Dog.

Int J Oral Maxillofac Implants 2019 November/December;34(6):1328–1336. Epub 2019 Sep 18.

Purpose: There is a lack of knowledge concerning the critical buccal bone thickness required for securing favorable functional and esthetic outcomes, conditioned to the dimensional changes after implant placement. A preclinical study was therefore carried out to identify the critical buccal bone wall thickness for minimizing bone resorption during physiologic and pathologic bone remodeling.

Materials And Methods: A randomized, two-arm in vivo study in healthy beagle dogs was carried out. The first group of dogs was sacrificed 8 weeks after implant placement for histomorphometric examination of postsurgical resorption of the buccal bone wall. The second group of dogs was monitored during three ligature-induced peri-implantitis episodes and a spontaneous progression episode. Morphometric and clinical variables were defined for the study of physiologic and pathologic buccal and lingual bone loss.

Results: Seventy-two implants were placed in healed mandibular ridges of 12 beagle dogs. Two groups were defined: 36 implants were placed in sites with a thin buccal bone wall (< 1.5 mm), and 36 were placed in sites with a thick buccal bone wall (≥ 1.5 mm). No implants failed during the study period. For the great majority of the histomorphometric parameters, a critical buccal bone wall thickness of at least 1.5 mm seemed to be essential for maintaining the buccal bone wall during physiologic and pathologic bone resorption. Suppuration (+) and mucosal recession (-) were more often associated with implants placed in sites with a thin buccal bone wall.

Conclusion: A critical buccal bone wall thickness of 1.5 mm at implant placement is advised, since a thicker peri-implant buccal bone wall (> 1.5 mm) is exposed to significantly less physiologic and pathologic bone loss compared with a thinner buccal bone wall (< 1.5 mm).
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http://dx.doi.org/10.11607/jomi.7657DOI Listing
December 2019

Influence of implant macrodesign and insertion connection technology on the accuracy of static computer-assisted implant surgery.

Clin Implant Dent Relat Res 2019 Oct 19;21(5):1073-1079. Epub 2019 Aug 19.

Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Objective: The aim of this study was to evaluate the effect of three different macrodesigns and two different insertion devices on the accuracy of static computer-assisted implant surgery (sCAIS).

Materials And Methods: Ninety implant replicas with three different macrodesigns: Soft tissue level (TL), bone level (BL), and bone level tapered (BLT) were placed in 30 dental models with two implant insertion devices: Guided adapter and guided screwed-in mount. Preoperative and postoperative positions of implants were compared and the mean angular deviation, crestal, and apical three-dimensional (3D) deviation were calculated for each implant macrodesign and each insertion device. Data were analyzed using analysis of variance, post hoc t-tests and Bonferroni-Holm's adjustment method. P values less than .05 were considered statistically significant.

Results: BLT implants had lower mean 3D deviation values at the crest and the apex when compared with 3D deviations with BL and TL implants (P < .05). Also, BLT implants had lower angular deviations, when compared with BL and TL Implants, however, angular deviations were not statistically significant (P > .05). Considering the insertion device method, no significant differences were noted between insertion devices irrespective of the deviation analyzed.

Conclusion: The macrodesign of dental implants may have an influence on the accuracy of sCAIS, with tapered designs offering slightly better positional accuracy than parallel-walled macrodesigns independent on the method of insertion used.
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http://dx.doi.org/10.1111/cid.12836DOI Listing
October 2019

Analysis of trends in implant therapy at a surgical specialty clinic: Patient pool, indications, surgical procedures, and rate of early failures-A 15-year retrospective analysis.

Clin Oral Implants Res 2019 Nov 30;30(11):1097-1106. Epub 2019 Aug 30.

Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Objectives: To evaluate the patient population over a 3-year period and to compare it to observations of the population at the same clinic over a period of 15 years.

Material And Methods: Records of patients receiving dental implants in the Department of Oral Surgery and Stomatology, University of Bern, between January 2014 and December 2016 were analyzed and then compared with data from patients treated between 2002 and 2004 and between 2008 and 2010. Patients were analyzed for demographics and for indications for therapy, as well as for presence or absence and type of complications. Inserted implants were analyzed for type, length, and diameter, as well as for the number and type of associated tissue regeneration procedures.

Results: Analysis revealed a continuous linear increase in the average age of patients seeking implant treatment. The most common indication for implant therapy was a single-tooth gap (STG) (50.5%), followed by distal extension situations (22.3%) and extended edentulous gaps (20.5%). A total of 60.8% of implants placed needed some type of bone augmentation, and 83.5% of implants placed in the anterior maxilla required simultaneous augmentation. Staged guided bone regeneration (GBR) was only necessary in 7% of the cases. Implant failure rates remained low at 0.6%, with postoperative hematomas being the most common postoperative complication (13.4%).

Conclusions: The rising demand for dental implants continues as the patient population ages. Single-tooth gaps remained consistently the most common indication for implant therapy in recent years. Proper case selection and evidence-based surgical protocols are essential for high success rates.
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http://dx.doi.org/10.1111/clr.13523DOI Listing
November 2019

Influence of surgical guide support and implant site location on accuracy of static Computer-Assisted Implant Surgery.

Clin Oral Implants Res 2019 Nov 20;30(11):1067-1075. Epub 2019 Aug 20.

Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Objective: To investigate the effect of surgical guide support and implant site location on the accuracy of static Computer-Assisted Implant Surgery (sCAIS) in partially edentulous patients.

Materials And Methods: 375 replica implants were inserted in 85 study models. Surgical implant placement was done using static 3D printed surgical guides, which were designed to be supported either by all the teeth present in the model (full arch), or by 4-teeth), 3-teeth or 2-teeth. Each study model included three single-tooth gap (STG) situations; one extraction socket site and two implants placed in a distal extension situation. Preplanned and postoperative implant positions were compared using the treatment-evaluation tool in digital software. 3-dimensional and angular deviations were measured. Statistical analysis was done using ANOVA, and pairwise t tests and Bonferroni-Holm's adjustment were applied as a post hoc test.

Results: Accuracy of surgical guides used in sCAIS was significantly affected by the number and type of teeth used for its support. Guides supported by 4 teeth were not significantly different from accuracy of full-arch-supported guides (p > .05). Guide support by posterior teeth was associated with an increased level of accuracy, when compared to anterior teeth guide support. Implants placed in extraction sockets were associated with significantly higher 3D and angular deviation values (p < .05), and surgical guides with a distal extension situation resulted in significantly higher deviation values (p < .05).

Conclusion: The number and location of teeth supporting the surgical guide can significantly influence the accuracy of sCAIS, with 4 teeth providing equal accuracy to full-arch guides in (STG) situations.
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http://dx.doi.org/10.1111/clr.13520DOI Listing
November 2019

Soft tissue response to dental implant closure caps made of either polyetheretherketone (PEEK) or titanium.

Clin Oral Implants Res 2019 Aug 12;30(8):808-816. Epub 2019 Jun 12.

Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Objective: Polyetheretherketone (PEEK) is a popular synthetic thermoplastic polymer for medical applications, but its clinical use suffers from several limitations. Therefore, the aim was to compare the soft tissue response to dental implant closure caps made of PEEK or titanium as evaluated by the occurrence of multinucleated giant cells (MNGCs).

Material And Methods: Forty-two implants were placed in the maxilla of seven miniature pigs. While commercially pure titanium (Ti) implants had a Ti closure cap, ceramic implants made of either zirconia (Zr) or alumina-toughened zirconia (Zr + Al) received a PEEK closure cap. Histomorphometry was performed to evaluate the number of small and large MNGCs being in contact with the PEEK or the Ti in different compartments of the implant systems.

Results: No histological signs of inflammation were noticed, and MNGCs were observed on both PEEK and Ti closure caps and on all three implant types. Significantly higher numbers of MNGCs were found on closure caps made of PEEK than on closure caps made of Ti on the external closure cap surface facing both soft (p = 0.0008 for PEEK on Zr and p = 0.0016 for PEEK on Zr + Al) and hard tissues (p = 0.016 for PEEK on Zr and p = 0.003 for PEEK on Zr + Al) as well as in the internal closure cap surface (p = 0.014 for PEEK on Zr and p = 0.0088 for PEEK on Zr + Al). No statistically significant differences in the number of MNGCs were observed on the three implant types.

Conclusions: Significantly more MNGCs were in contact with PEEK than with Ti closure caps.
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http://dx.doi.org/10.1111/clr.13487DOI Listing
August 2019

The influence of guided sleeve height, drilling distance, and drilling key length on the accuracy of static Computer-Assisted Implant Surgery.

Clin Implant Dent Relat Res 2019 Feb 27;21(1):101-107. Epub 2018 Dec 27.

Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Objective: The aim of this study was to evaluate the effect of guided sleeve height, drilling distance, and guided key height on accuracy of static Computer-Assisted Implant Surgery (sCAIS).

Materials And Methods: Pre and post-operative positions of implants placed in duplicate dental models were compared and recorded after placement of implants according to a standardized treatment planning and execution sCAIS protocol. Guided sleeve heights: 2 mm, 4 mm, 6 mm and guided key heights: 1 mm and 3 mm were equally randomized in six test groups with varying implant lengths (10-16 mm) and surgical drilling protocols. The mean crestal and apical three-dimensional (3D) deviation, as well as the angular deviation were calculated for each group. Data was analyzed using multivariate analysis anova. P values less than .05 were considered statistically significant. All P values of post-hoc tests were corrected for multiple testing using Bonferroni-Holm's adjustment method.

Results: 3D implant positioning accuracy was not significantly affected by the difference in sleeve height alone or by the implant length alone (P > .05). However, 3D and angular deviation values became significantly higher as the total drilling distance below the guided sleeve increased and significantly became lower as the guided key height above the sleeve increased. 18 mm drilling distance resulted in a significantly higher deviation, when compared to 14 mm or 16 mm drilling distances, irrespective of sleeve height or implant length (P < .01). 3 mm key height resulted in significantly less 3D deviation than 1 mm key height (P < .01).

Conclusion: Decreasing the drilling distance below the guided sleeve, by using shorter sleeve heights or shorter implants can significantly increase the accuracy of sCAIS.
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http://dx.doi.org/10.1111/cid.12705DOI Listing
February 2019

Group 2 ITI Consensus Report: Prosthodontics and implant dentistry.

Clin Oral Implants Res 2018 Oct;29 Suppl 16:215-223

Department of Restorative Dentistry, Harvard School of Dental Medicine, Boston, Massachusetts.

Objectives: Working Group 2 was convened to address topics relevant to prosthodontics and dental implants. Systematic reviews were developed according to focused questions addressing (a) the number of implants required to support fixed full-arch restorations, (b) the influence of intentionally tilted implants compared to axial positioned implants when supporting fixed dental prostheses (FDPs), (c) implant placement and loading protocols, (d) zirconia dental implants, (e) zirconia and metal ceramic implant supported single crowns and (f) zirconia and metal ceramic implant supported FDPs.

Materials And Methods: Group 2 considered and discussed information gathered in six systematic reviews. Group participants discussed statements developed by the authors and developed consensus. The group developed and found consensus for clinical recommendations based on both the statements and the experience of the group. The consensus statements and clinical recommendations were presented to the plenary (gathering of all conference attendees) and discussed. Final versions were developed after consensus was reached.

Results: A total of 27 consensus statements were developed from the systematic reviews. Additionally, the group developed 24 clinical recommendations based on the combined expertise of the participants and the developed consensus statements.

Conclusions: The literature supports the use of various implant numbers to support full-arch fixed prostheses. The use of intentionally tilted dental implants is indicated when appropriate conditions exist. Implant placement and loading protocols should be considered together when planning and treating patients. One-piece zirconia dental implants can be recommended when appropriate clinical conditions exist although two-piece zirconia implants should be used with caution as a result of insufficient data. Clinical performance of zirconia and metal ceramic single implant supported crowns is similar and each demonstrates significant, though different, complications. Zirconia ceramic FDPs are less reliable than metal ceramic. Implant supported monolithic zirconia prostheses may be a future option with more supporting evidence.
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http://dx.doi.org/10.1111/clr.13298DOI Listing
October 2018

Implant placement and loading protocols in partially edentulous patients: A systematic review.

Clin Oral Implants Res 2018 Oct;29 Suppl 16:106-134

Melbourne Dental School, The University of Melbourne, Melbourne, Vic., Australia.

Objectives: To systematically review the evidence for the clinical outcome of fixed implant prostheses treated with different combinations of implant placement and loading protocols in partially edentulous patients.

Materials And Methods: An electronic search was performed in Medline, Embase, and Central to identify studies investigating the outcome of implants subjected to immediate placement + immediate restoration/loading (Type 1A), immediate placement + early loading (Type 1B), immediate placement + conventional loading (Type 1C), early placement + immediate restoration/loading (Type 2-3A), early placement + early loading (Type 2-3B), early placement + conventional loading (Type 2-3C), late placement + immediate restoration/loading (Type 4A), late placement + early loading (Type 4B), late placement + conventional loading (Type 4C) with implant-supported fixed dental prostheses (IFDPs) in partially edentulous patients. Only human studies with at least 10 cases and a minimum follow-up time of 12 months, reporting on solid-screw-type implants with rough surfaces and an intra-osseous diameter between 3 and 6 mm, were included. A cumulative survival rate for each type of the implant placement and loading protocols was weighted by the duration of follow-up and number of implants.

Results: The search provided 5,248 titles from which 2,362 abstracts and 449 full-text articles were screened. A total of 69 publications that comprised 23 comparative studies (15 randomized controlled trials, 7 controlled clinical trials) and 47 noncomparative studies (34 prospective cohort studies, 13 retrospective cohort studies) were included for analysis. Considerable heterogeneity in study design was found, and therefore, a meta-analysis of controlled studies was not possible. The weighted cumulative survival rate of each type of placement and loading protocol was 98.4% (Type 1A), 98.2% (Type 1B), 96.0% (Type 1C), 100% (Type 2-3B), 96.3% (Type 2-3C), 97.9% (Type 4A), 98.3% (Type 4B), and 97.7% (Type 4C). Type 1C, Type 2-3C, Type 4B, and Type 4C were scientifically and clinically validated (SCV). Type 1A, Type 1B, and Type 4A were clinically documented (CD), and Type 2-3A and Type 2-3B were clinically insufficiently documented (CID).

Conclusions: Evaluating outcomes in oral implantology by combining the placement and loading protocols are paramount. The selected loading protocol appears to influence the outcome of immediate implant placement.
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http://dx.doi.org/10.1111/clr.13276DOI Listing
October 2018

Diagnostic accuracy of the implant stability quotient in monitoring progressive peri-implant bone loss: An experimental study in dogs.

Clin Oral Implants Res 2018 Oct 28;29(10):1016-1024. Epub 2018 Sep 28.

Department of Oral Surgery and Stomatology, ZMK School of Dental Medicine, University of Bern, Bern, Switzerland.

Objectives: To investigate the impact of progressive bone loss in an experimental peri-implantitis model in the dog upon the implant stability quotient (ISQ) measured in the course of induced and spontaneous conditions of disease, and to evaluate the association between the clinical parameters and ISQ.

Materials And Methods: Seventy-two implants were placed in 12 Beagle dogs. Of these, 36 implants in six dogs were assessed during ligature-induced peri-implantitis (three timepoints) and at one timepoint following a period of spontaneous progression. The ISQ was recorded using resonance frequency analysis (RFA). Furthermore, the clinical peri-implant parameters were registered at four sites per implant at each timepoint. Marginal bone loss (MBL) was determined using computed tomography at four sites per implant and bone-to-implant contact (BIC) was assessed from histological samples. A linear regression model was estimated by generalized estimation equations (GEEs) in order to study the MBL-ISQ values at each measurement timepoint. Pearson's correlation test was applied.

Results: None of the implants failed during the study period. At implant level, a strong negative correlation was found for all timepoints between ISQ and MBL (r = -0.58; p < 0.001). Accordingly, as follow-up progressed, lower ISQ and higher MBL values were observed. A prediction of MBL depending on the ISQ values and timepoints showed a decrease in one ISQ unit to be related to ~1 mm of MBL. Likewise, a statistically significant correlation was found between BIC and ISQ evaluated after spontaneous chronification of peri-implantitis (r = 0.34; p = 0.04). Nevertheless, the ISQ values failed to correlate to any of the clinical parameters recorded.

Conclusion: Resonance frequency analysis seems accurate in diagnosing progressive bone loss, as a statistically significant decrease in ISQ was recorded in the course of peri-implant disease. Nevertheless, the clinical relevance of this observation as a diagnostic tool is debatable, since implant stability remains high.
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http://dx.doi.org/10.1111/clr.13368DOI Listing
October 2018

Osseointegration of ultrafine-grained titanium with a hydrophilic nano-patterned surface: an in vivo examination in miniature pigs.

Biomater Sci 2018 Aug;6(9):2448-2459

Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, 3010 Bern, Switzerland.

Advances in biomaterials science and implant surface technology have made dental implants more predictable and implant therapy more attractive to patients. Surgical interventions are becoming less invasive, and patients heal faster and suffer less morbidity. In this preclinical in vivo study, we compared a new ultra-fine grained titanium (ufgTi) implant material with a hydrophilic nano-patterned surface to commercially pure titanium (cpTi) in a well-established animal model. CpTi grade 4 was subjected to Equal Channel Angular Pressing (ECAP), followed by a cold drawing process that provided ultra-fine-grained titanium (ufgTi) with a mean grain size of 300 nm. After metallographic assessment, the surface topography was characterized by laser confocal microscopy and atomic force microscopy. UfgTi and cpTi implants were inserted in the mandible and maxilla of miniature pigs that healed for 4 and for 8 weeks. Osseointegration was assessed by biomechanical torque out analysis, histomorphometric evaluation, and micro-CT analysis. The metallographic properties of UfgTi were significantly better than those of cpTi. Their surface topographies had similar hydrophilic nano-patterned characteristics, with no significant differences in the nanometre range. Histomorphometric and biomechanical torque out analysis revealed no significant differences between ufgTi and cpTi in environments of either low (maxilla) or high (mandible) bone density. We obtained high bone-to-implant contact values irrespective of the bony microarchitecture even when the bone mineral density was low. Overall, this investigation suggests that ufgTi forms a hydrophilic nano-patterned surface with superior metallographic properties compared to cpTi and high levels of osseointegration. Thus, ufgTi has therapeutic potential as a future strategy for the development of small diameter implants to enable less invasive treatment concepts, reduce patient morbidity and may also lower the costs of patient care.
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http://dx.doi.org/10.1039/c8bm00671gDOI Listing
August 2018

Bone-conditioned medium contributes to initiation and progression of osteogenesis by exhibiting synergistic TGF-β1/BMP-2 activity.

Int J Oral Sci 2018 06 12;10(2):20. Epub 2018 Jun 12.

Department of Oral Surgery and Stomatology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Guided bone regeneration (GBR) often utilizes a combination of autologous bone grafts, deproteinized bovine bone mineral (DBBM), and collagen membranes. DBBM and collagen membranes pre-coated with bone-conditioned medium (BCM) extracted from locally harvested autologous bone chips have shown great regenerative potential in GBR. However, the underlying molecular mechanism remains largely unknown. Here, we investigated the composition of BCM and its activity on the osteogenic potential of mesenchymal stromal cells. We detected a fast and significant (P < 0.001) release of transforming growth factor-β1 (TGF-β1) from autologous bone within 10 min versus a delayed bone morphogenetic protein-2 (BMP-2) release from 40 min onwards. BCMs harvested within short time periods (10, 20, or 40 min), corresponding to the time of a typical surgical procedure, significantly increased the proliferative activity and collagen matrix production of BCM-treated cells. Long-term (1, 3, or 6 days)-extracted BCMs promoted the later stages of osteoblast differentiation and maturation. Short-term-extracted BCMs, in which TGF-β1 but no BMP-2 was detected, reduced the expression of the late differentiation marker osteocalcin. However, when both growth factors were present simultaneously in the BCM, no inhibitory effects on osteoblast differentiation were observed, suggesting a synergistic TGF-β1/BMP-2 activity. Consequently, in cells that were co-stimulated with recombinant TGF-β1 and BMP-2, we showed a significant stimulatory and dose-dependent effect of TGF-β1 on BMP-2-induced osteoblast differentiation due to prolonged BMP signaling and reduced expression of the BMP-2 antagonist noggin. Altogether, our data provide new insights into the molecular mechanisms underlying the favorable outcome from GBR procedures using BCM, derived from autologous bone grafts.
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http://dx.doi.org/10.1038/s41368-018-0021-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5997631PMC
June 2018

Novel Collagen Matrix to Increase Tissue Thickness Simultaneous with Guided Bone Regeneration and Implant Placement in Esthetic Implant Sites: A Feasibility Study.

Int J Periodontics Restorative Dent 2018 Jul/Aug;38(July/August):575-582

The purpose of this case series was to assess safety and feasibility of a novel resorbable collagen matrix (CMX) to enhance tissue thickness simultaneous with implant placement and guided bone regeneration (GBR) in esthetic sites over an 8-week healing period. Soft tissue thickness at implant sites and adjacent teeth was monitored with an ultrasonic device. Overall tissue contour changes were assessed by sequential digital surface model superimpositions. Periodontal parameters and patient-related outcomes revealed no significant changes. Combining a novel CMX and GBR revealed a significant soft tissue thickness increase of 1.56 mm at implant sites after 8 weeks, with no significant decrease between 4 and 8 weeks. The overall tissue contour increase was most significant at a distance of 5 mm from the mucosal margin, corresponding to a tissue increase at the implant shoulder area. No effect was observed at adjacent teeth after 8 weeks.
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http://dx.doi.org/10.11607/prd.3700DOI Listing
December 2018

A safe holder for adjusting indirect prostheses: The silicone cube technique.

J Prosthet Dent 2018 Aug 5;120(2):313-315. Epub 2018 Apr 5.

Chairman Emeritus, Division of Fixed Prosthodontics and Biomaterials, School of Dental Medicine, University of Geneva, Geneva; and Guest Professor, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.

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http://dx.doi.org/10.1016/j.prosdent.2017.11.005DOI Listing
August 2018

Bone response to functionally loaded, two-piece zirconia implants: A preclinical histometric study.

Clin Oral Implants Res 2018 Mar 30;29(3):277-289. Epub 2017 Dec 30.

Department of Periodontics, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.

Objective: To evaluate the bone response to a two-piece zirconia implant in comparison with a control titanium implant in the canine mandible 4 and 16 weeks after restoration.

Material And Methods: Zirconia and titanium implants were alternately placed bilaterally in healed mandibular molar and premolar sites of five canines. Full-ceramic single-tooth restorations were cemented after 6 weeks of transmucosal healing, allowing for full functional loading of the implants. Histologic and histometric analyses were performed on orofacial and mesiodistal undecalcified sections of the specimens obtained upon sacrifice after 4 and 16 weeks of functional loading. Bone-to-implant contact (BIC), multinucleated giant cells-to-implant contact (MIC), crestal bone level, and peri-implant bone density were histometrically assessed.

Results: All 60 implants and 60 restorations were still in function after 4 and 16 weeks of loading in both test and control groups. No implant loss, no implant or abutment fracture, and no chipping of the restorations could be detected. Histometric analysis showed no statistically significant differences between zirconia and titanium implants in BIC, crestal bone level, and peri-implant bone density at both time points. Between 4 and 16 weeks, the crestal bone level around zirconia implants showed a small but statistically significant increase in its distance from the implant shoulder. MIC was very low on both implant types and both time points and decreased statistically significantly overtime.

Conclusion: The present two-piece zirconia implant showed a similar bone integration compared to the titanium implant with similar surface morphology after 4 and 16 weeks of loading.
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http://dx.doi.org/10.1111/clr.13112DOI Listing
March 2018

Morphologic Patterns of the Atrophic Posterior Maxilla and Clinical Implications for Bone Regenerative Therapy.

Int J Periodontics Restorative Dent 2017 Sep/Oct;37(5):e279-e289

Regenerative therapies are commonly needed prior to implant placement in the posterior maxilla following tooth extraction. The aim of this study was to investigate the anatomical features of the atrophic posterior maxilla that might affect surgical approach selection and technique and risk of intra- and postoperative complications. Cone beam computed tomography files were screened to identify pristine atrophic maxillary ridges in need of bone augmentation (ridge height < 10 mm). Ridge height and width and lateral wall thickness (LWT) were measured at different levels, and palatonasal recess and lateral wall morphology were calculated. The influence of site was assessed using generalized estimation equations. The linear correlation between parameters was estimated with Pearson coefficient, and principal component analysis (PCA) was performed to establish patterns of multiple correlations. In the 433 edentulous sites and 6,062 measurements analyzed, the strongest correlations corresponded to LWT measurements at the different levels. Most of the parameters examined presented linearity (P < .001), allowing establishment of four main morphologic patterns according to anatomical features. The anatomical structures of the atrophic posterior maxilla follow linear patterns that might predict complications due to an anatomical feature and thus success in regenerative therapy.
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http://dx.doi.org/10.11607/prd.3228DOI Listing
June 2018

Influence of the Posterior Mandible Ridge Morphology on Virtual Implant Planning.

Int J Oral Maxillofac Implants 2017 Jul/Aug;32(4):801-806

Purpose: The purpose of this study was to examine the anatomy of the mandibular posterior region to develop an anatomical categorization for implant-prosthodontic planning.

Materials And Methods: Using cone beam computed tomography scans, 313 cross-sectional views of edentulous posterior mandibular sites were evaluated with respect to the anatomical ridge morphology. Virtual implant planning was performed, and the need for bone grafting was assessed. The level of complexity for planning implants in those positions was assessed. Sites were classified as straightforward, advanced, or complex sites based on the need for bone grafting.

Results: Five well-defined cross-sectional configurations were observed: straight (53.6%), oblique (26.2%), s-shape (7.4%), hourglass shape (1.9%), and basal bone (10.8%). There was a statistically significant association between the ridge shape and the feasibility of placing an implant with or without bone grafting; the straight and oblique ridge shapes were more likely to be associated with a favorable anatomy for implant placement.

Conclusion: The ridge shape significantly influenced the ease or difficulty of placing an implant. The s-shape, hourglass, and basal bone posterior mandibular cross-sectional shapes were associated with a higher degree of difficulty.
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http://dx.doi.org/10.11607/jomi.5546DOI Listing
February 2018

Correlation of Three-Dimensional Radiologic Data with Subsequent Treatment Approach in Patients with Peri-implantitis: A Retrospective Analysis.

Int J Periodontics Restorative Dent 2017 Jul/Aug;37(4):481-489

The purpose of this retrospective radiographic study was to evaluate and correlate the dimensions and morphology of peri-implant bone defects as determined via cone beam computed tomography (CBCT) scans with regard to the selected treatment approach. Vertical and horizontal peri-implant bone defects (mesial, distal, mesio-oral, mesiobuccal, disto-oral, distobuccal, oral, and buccal) in peri-implantitis cases were measured. Three-dimensional data and defect morphology were correlated to the treatment approach chosen (explantation versus implant retention). A total of 19 patients and 28 implants met the inclusion criteria, resulting in a sample size of 224 sites and a total of 896 measurements. The mean percent bone loss did not correlate to the type of treatment chosen (P = .1286). In contrast, when only the maximum vertical values per implant were selected, maximum percent bone loss exhibited a significant correlation to the type of treatment chosen (P = .0021). The effect of the defect morphology on the treatment strategy chosen did not show a statistically significant correlation (P = .4685). Based on the data presented, the maximum bone loss around the implant seems to be a critical factor in deciding whether or not an implant should be explanted. The use of CBCT for treatment planning in cases of peri-implantitis can offer valuable additional information but should be considered only after initial clinical examination and two-dimensional imaging.
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http://dx.doi.org/10.11607/prd.2844DOI Listing
May 2018

Effects of platelet rich plasma (PRP) on human gingival fibroblast, osteoblast and periodontal ligament cell behaviour.

BMC Oral Health 2017 Jun 2;17(1):91. Epub 2017 Jun 2.

Department of Periodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Background: The use of platelet rich plasma (PRP, GLO) has been used as an adjunct to various regenerative dental procedures. The aim of the present study was to characterize the influence of PRP on human gingival fibroblasts, periodontal ligament (PDL) cells and osteoblast cell behavior in vitro.

Methods: Human gingival fibroblasts, PDL cells and osteoblasts were cultured with conditioned media from PRP and investigated for cell migration, proliferation and collagen1 (COL1) immunostaining. Furthermore, gingival fibroblasts were tested for genes encoding TGF-β, PDGF and COL1a whereas PDL cells and osteoblasts were additionally tested for alkaline phosphatase (ALP) activity, alizarin red staining and mRNA levels of osteoblast differentiation markers including Runx2, COL1a2, ALP and osteocalcin (OCN).

Results: It was first found that PRP significantly increased cell migration of all cells up to 4 fold. Furthermore, PRP increased cell proliferation at 3 and 5 days of gingival fibroblasts, and at 3 days for PDL cells, whereas no effect was observed on osteoblasts. Gingival fibroblasts cultured with PRP increased TGF-β, PDGF-B and COL1 mRNA levels at 7 days and further increased over 3-fold COL1 staining at 14 days. PDL cells cultured with PRP increased Runx2 mRNA levels but significantly down-regulated OCN mRNA levels at 3 days. No differences in COL1 staining or ALP staining were observed in PDL cells. Furthermore, PRP decreased mineralization of PDL cells at 14 days post seeding as assessed by alizarin red staining. In osteoblasts, PRP increased COL1 staining at 14 days, increased COL1 and ALP at 3 days, as well as increased ALP staining at 14 days. No significant differences were observed for alizarin red staining of osteoblasts following culture with PRP.

Conclusions: The results demonstrate that PRP promoted gingival fibroblast migration, proliferation and mRNA expression of pro-wound healing molecules. While PRP induced PDL cells and osteoblast migration and proliferation, it tended to have little to no effect on osteoblast differentiation. Therefore, while the effects seem to favor soft tissue regeneration, the additional effects of PRP on hard tissue formation of PDL cells and osteoblasts could not be fully confirmed in the present in vitro culture system.
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http://dx.doi.org/10.1186/s12903-017-0381-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5457736PMC
June 2017

Combination of Collagen Barrier Membrane with Enamel Matrix Derivative-Liquid Improves Osteoblast Adhesion and Differentiation.

Int J Oral Maxillofac Implants 2017 Jan/Feb;32(1):196-203

Purpose: Collagen barrier membranes were first introduced to regenerative periodontal and oral surgery to prevent fast ingrowing soft tissues (ie, epithelium and connective tissue) into the defect space. More recent attempts have aimed at combining collagen membranes with various biologics/growth factors to speed up the healing process and improve the quality of regenerated tissues. Recently, a new formulation of enamel matrix derivative in a liquid carrier system (Osteogain) has demonstrated improved physico-chemical properties for the adsorption of enamel matrix derivative to facilitate protein adsorption to biomaterials. The aim of this pioneering study was to investigate the use of enamel matrix derivative in a liquid carrier system in combination with collagen barrier membranes for its ability to promote osteoblast cell behavior in vitro.

Materials And Methods: Undifferentiated mouse ST2 stromal bone marrow cells were seeded onto porcine-derived collagen membranes alone (control) or porcine membranes + enamel matrix derivative in a liquid carrier system. Control and enamel matrix derivative-coated membranes were compared for cell recruitment and cell adhesion at 8 hours; cell proliferation at 1, 3, and 5 days; and real-time polymerase chain reaction (PCR) at 3 and 14 days for genes encoding Runx2, collagen1alpha2, alkaline phosphatase, and bone sialoprotein. Furthermore, alizarin red staining was used to investigate mineralization.

Results: A significant increase in cell adhesion was observed at 8 hours for barrier membranes coated with enamel matrix derivative in a liquid carrier system, whereas no significant difference could be observed for cell proliferation or cell recruitment. Enamel matrix derivative in a liquid carrier system significantly increased alkaline phosphatase mRNA levels 2.5-fold and collagen1alpha2 levels 1.7-fold at 3 days, as well as bone sialoprotein levels twofold at 14 days postseeding. Furthermore, collagen membranes coated with enamel matrix derivative in a liquid carrier system demonstrated a sixfold increase in alizarin red staining at 14 days when compared with collagen membrane alone.

Conclusion: The combination of enamel matrix derivative in a liquid carrier system with a barrier membrane significantly increased cell attachment, differentiation, and mineralization of osteoblasts in vitro. Future animal testing is required to fully characterize the additional benefits of combining enamel matrix derivative in a liquid carrier system with a barrier membrane for guided bone or tissue regeneration.
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http://dx.doi.org/10.11607/jomi.5011DOI Listing
March 2017