Implant-supported single all-ceramic crowns made from prefabricated (stock) or individualized CAD/CAM zirconia abutments: A 5 year randomized clinical trial.

AIM: The aim of this randomized, prospective, and clinical multicenter study was to compare the overall clinical performance of two restorative options over a 5-year period: individualized CAD/CAM abutments veneered with a hand-layered ceramic, and prefabricated zirconium dioxide abutments veneered with press ceramic and inserted into a single edentulous gap in the anterior maxilla. MATERIALS AND METHODS: Forty subjects were recruited from two universities: 20 from the University of XX and 20 from the University of XY. Each subject received an implant to restore a single edentulous gap in the maxillary anterior region (14-24 FDI). 20 patients were randomized into each Group. Group A received a one-piece single crown produced from a prefabricated zirconia abutment with pressed ceramic and Group B received an individualized CAD/CAM zirconia abutment with a hand-layered technique. After 5 years, the aesthetic and radiographic parameters were assessed. RESULTS: Group A had four dropouts and one failure, resulting in a 95% survival rate and 95% success rate. Group B had two dropouts and two failures which resulted in a 90% survival rate and 90% success rate. No crestal bone level changes were observed, with a mean DIB of 0.06 mm in Group A and 0.09 mm in Group B. No statistically significant differences were present at baseline, 6 months, 1 year, 3 years, or 5 years for DIB values between time points and groups. Pink aesthetic score/white aesthetic score, Peri-Implant and Crown Index, and Implant Crown Aesthetic Index values were stable over time at all five points for both groups. CONCLUSION: Both implant-supported restorative options represent a valuable treatment option for the restoration of implant crowns in the anterior maxilla. CLINICAL SIGNIFICANCE: In general, the use of ceramic abutments in the anterior zone represents a valuable treatment procedure with both standardized and CAD/CAM individualized abutments and following the recommendations from the respective manufacturer(s).

Complications and treatment errors in implant positioning in the aesthetic zone: Diagnosis and possible solutions.

Incorrect implant positioning can lead to functional and aesthetic compromise. Implant positioning errors can occur in three dimensions: mesiodistal, corono-apical, and orofacial. Treatment solutions to manage adverse outcomes through positioning errors require an understanding of the underlying conditions and of those factors that may have led to the error being committed in the first place. These types of complications usually occur because of human factors. If errors do occur with adverse aesthetic outcomes, they are difficult and sometimes impossible to correct. Connective tissue grafts to reverse recession defects are only feasible in defined situations. The option to remove and replace the implant may be the only recourse, provided the removal process does not further compromise the site. Error in judgment by the clinician.

Guided bone regeneration in implant dentistry: Basic principle, progress over 35 years, and recent research activities.

Bone augmentation procedures are frequent today in implant patients, since an implant should be circumferentially anchored in bone at completion of bone healing to have a good long-term stability. The best documented surgical technique to achieve this goal is guided bone regeneration (GBR) utilizing barrier membranes in combination with bone fillers. This clinical review paper reflects 35 years of development and progress with GBR. In the 1990s, GBR was developed by defining the indications for GBR, examining various barrier membranes, bone grafts, and bone substitutes. Complications were identified and reduced by modifications of the surgical technique. Today, the selection criteria for various surgical approaches are much better understood, in particular, in post-extraction implant placement. In the majority of patients, biodegradable collagen membranes are used, mainly for horizontal bone augmentation, whereas bioinert PTFE membranes are preferred for vertical ridge augmentation. The leading surgeons are using a composite graft with autogenous bone chips to accelerate bone formation, in combination with a low-substitution bone filer to better maintain the augmented bone volume over time. In addition, major efforts have been made since the millenium change to reduce surgical trauma and patient morbidity as much as possible. At the end, some open questions related to GBR are discussed.

Influence of loading and grafting on hard- and soft-tissue healing at immediately placed implants: An experimental study in minipigs.

AIM: To histologically evaluate the influence of (1) loading and (2) grafting on osseointegration and peri-implant soft-tissue healing at immediately placed, self-cutting progressive tissue-level implants (TLX) in a minipig model. MATERIALS AND METHODS: TLX implants (n = 56) were immediately placed following the extraction of the mandibular first and second premolars, bilaterally, in a total of n = 14 minipigs. In each animal, the implant sites were allocated to the following four groups: (1) unloaded with simultaneous grafting using a bovine bone mineral; (2) unloaded without grafting; (3) loaded with simultaneous grafting; and (4) loaded without grafting. Histomorphometric assessments at 4 and 12 weeks (n = 7 animals each) included primary (i.e., bone-to-implant contact [BIC]) and secondary outcome measures (e.g., first BIC [fBIC], junctional epithelium length [JE], connective tissue contact length [CTC], biological width [BW = JE + CTC]). RESULTS: At 4 weeks, mean BIC values ranged from 74.5 ± 11.6% in Group 2 to 83.8 ± 13.3% in Group 1, and, at 12 weeks, from 75.5% ± 7.9% in Group 2 to 79.9 ± 8.6% in Group 1. Multivariate linear mixed regression did not reveal any associations between BIC and implant loading or grafting at 4 and 12 weeks. At 12 weeks, significantly higher fBIC values were noted in Group 2 when compared with Group 1. All groups showed comparable JE, CTC, and BW values. CONCLUSIONS: Implant loading and grafting had no major effects on osseointegration and peri-implant soft tissue healing at TLX implants.

Influence of buccal bone wall thickness on the peri-implant hard and soft tissue dimensional changes: A systematic review

BACKGROUND: The significance on the association between the peri-implant bucco-lingual dimension (BLD) at the stage of implant placement and the occurrence of biological and esthetic complications is yet unknown. MATERIAL AND METHODSS: Systematic screening of electronic sources was carried out to identify clinical and preclinical studies reporting on the baseline BLD and/or buccal bone thickness (BBT) values. A secondary objective was to assess the effect of simultaneous grafting at sites with deficient or no buccal bone wall (BBW) at baseline. The primary outcome variables were BBT, BLD, and buccal vertical bone loss (VBL) at re-evaluation. Moreover, radiographic, clinical, and patient-reported outcome measures (PROMs) were evaluated. RESULTS: Overall, 12 clinical and four preclinical studies met the inclusion criteria. Inconsistencies were found in defining the critical BBT across the clinical and preclinical data evaluated. The clinical evidence demonstrated that during healing, dimensional changes occur in the alveolar bone and in the BBW that may compromise the integrity of the peri-implant bone, leading to VBL and mucosal recession (MR), particularly in scenarios exhibiting a thin BBW. The preclinical evidence validated the fact that implants placed in the presence of a thin BBW, are more prone to exhibit major dimensional changes and VBL. Moreover, the clinical data supported that, in scenarios where dehiscence-type defects occur and are left for spontaneous healing, greater VBL and MR together with the occurrence of biologic complications are expected. Furthermore, the augmentation of dehiscence-type defects is associated with hard and soft tissue stability. PROMs were not reported. CONCLUSIONS: Dimensional changes occur as result of implant placement in healed ridges that may lead to instability of the peri-implant hard and soft tissues. Sites presenting a thin BBW are more prone to exhibit major changes that may compromise the integrity of the buccal bone and may lead to biologic and esthetic complications.

Influence of buccal bone wall thickness on the peri-implant hard and soft tissue dimensional changes: A systematic review.

BACKGROUND: The significance on the association between the peri-implant bucco-lingual dimension (BLD) at the stage of implant placement and the occurrence of biological and esthetic complications is yet unknown. MATERIAL AND METHODS: Systematic screening of electronic sources was carried out to identify clinical and preclinical studies reporting on the baseline BLD and/or buccal bone thickness (BBT) values. A secondary objective was to assess the effect of simultaneous grafting at sites with deficient or no buccal bone wall (BBW) at baseline. The primary outcome variables were BBT, BLD, and buccal vertical bone loss (VBL) at re-evaluation. Moreover, radiographic, clinical, and patient-reported outcome measures (PROMs) were evaluated. RESULTS: Overall, 12 clinical and four preclinical studies met the inclusion criteria. Inconsistencies were found in defining the critical BBT across the clinical and preclinical data evaluated. The clinical evidence demonstrated that during healing, dimensional changes occur in the alveolar bone and in the BBW that may compromise the integrity of the peri-implant bone, leading to VBL and mucosal recession (MR), particularly in scenarios exhibiting a thin BBW. The preclinical evidence validated the fact that implants placed in the presence of a thin BBW, are more prone to exhibit major dimensional changes and VBL. Moreover, the clinical data supported that, in scenarios where dehiscence-type defects occur and are left for spontaneous healing, greater VBL and MR together with the occurrence of biologic complications are expected. Furthermore, the augmentation of dehiscence-type defects is associated with hard and soft tissue stability. PROMs were not reported. CONCLUSIONS: Dimensional changes occur as result of implant placement in healed ridges that may lead to instability of the peri-implant hard and soft tissues. Sites presenting a thin BBW are more prone to exhibit major changes that may compromise the integrity of the buccal bone and may lead to biologic and esthetic complications.

Group 1 ITI Consensus Report: The role of bone dimensions and soft tissue augmentation procedures on the stability of clinical, radiographic, and patient-reported outcomes of implant treatment.

OBJECTIVES: The aims of Working Group 1 were to address the role (i) of the buccolingual bone dimensions after implant placement in healed alveolar ridge sites on the occurrence of biologic and aesthetic complications, and (ii) of soft tissue augmentation (STA) on the stability of clinical, radiographic, and patient-related outcomes of implant treatments. MATERIALS AND METHODS: Two systematic reviews were prepared in advance of the Consensus Conference and were discussed among the participants of Group 1. Consensus statements, clinical recommendations, recommendations for future research, and reflections on patient perspectives were based on structured group discussions until consensus was reached among the entire group of experts. The statements were then presented and accepted following further discussion and modifications as required by the plenary. RESULTS: Dimensional changes of the alveolar ridge occurred after implant placement in healed sites, and a reduction in buccal bone wall thickness (BBW) of 0.3 to 1.8 mm was observed. In healed sites with a BBW of <1.5 mm after implant placement, increased vertical bone loss, and less favorable clinical and radiographic outcomes were demonstrated. Implants with buccal dehiscence defects undergoing simultaneous guided bone regeneration, showed less vertical bone loss, and more favorable clinical and radiographic outcomes, compared to non-augmented dehiscence defects during initial healing. At healthy single implant sites, probing depths, bleeding and plaque scores, and interproximal bone levels evaluated at 1 year, remained stable for up to 5 years, with or without STA. When single implant sites were augmented with connective tissue grafts, either for soft tissue phenotype modification or buccal soft tissue dehiscence, stable levels of the soft tissue margin, and stable or even increased soft tissue thickness and/or width of keratinized mucosa could be observed from 1 to 5 years. In contrast, non-augmented sites were more prone to show apical migration of the soft tissue margin in the long-term. Favorable aesthetic and patient-reported outcomes after STA were documented to be stable from 1 to 5 years. CONCLUSIONS: It is concluded that dimensional changes of the alveolar ridge occur after implant placement in healed sites and that sites with a thin BBW after implant placement are prone to exhibit less favorable clinical and radiographic outcomes. In addition, it is concluded that STA can provide stable clinical, radiographic, aesthetic, and patient-reported outcomes in the medium and long-term.

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

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 (ndogs  = 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-1ß positively correlated with probing pocket depth (r = .18; P = .03). During spontaneous progression, H implants displayed statistically significant lower levels of IL-1ß (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-1ß is associated with pocket probing depth and influenced by implant surface characteristics during the spontaneous progression phase.

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

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.

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

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.

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.

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.

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

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 (ZrO2 ) or titanium-zirconium (Ti-Zr) alloy implants. MATERIALS AND METHODS: Ti, Ti-Zr or ZrO2 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. ZrO2 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.

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.

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.

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.

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.

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

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.

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

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.

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

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.

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

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.

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

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.

Group 2 ITI Consensus Report: Prosthodontics and implant dentistry.

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.