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Aim To investigate the immunohistochemical characteristics of a highly porous synthetic bone substitute and a cross-linked collagen membrane for guided bone regeneration. Methods Three experimental groups were randomly allocated at chronic peri-implant dehiscence defect in 8 beagle dogs: (i) biphasic calcium phosphate covered by a cross-linked collagen membrane (test group), (ii) deproteinized bovine bone mineral covered by a natural collagen membrane (positive control) and (iii) no treatment (negative control). After 8 and 16 weeks of submerged healing, dissected tissue blocks were processed for immunohistochemical analysis. Seven antibodies were used to detect the remaining osteogenic and angiogenic potential, and quantitative immunohistochemical analysis was done by software. Results The antigen reactivity of alkaline phosphatase was significantly higher in the test group compared to the positive and negative controls, and it maintained till 16 weeks. The intensity of osteocalcin was significantly higher in the positive control at 8 weeks than the other groups, but significantly decreased at 16 weeks and no difference was found between the groups. A significant large number of TRAP-positive cells were observed in the test group mainly around the remaining particles at 16 weeks. The angiogenic potential was comparable between the groups showing no difference in the expression of transglutaminase II and vascular endothelial growth factor. Conclusion Guided bone regeneration combining a highly porous biphasic calcium phosphate synthetic biomaterial with a crosslinked collagen membrane, resulted in extended osteogenic potential when compared to the combination of deproteinized bovine bone mineral and a native collagen membrane.

OBJECTIVES: To observe the sequential healing of lateral onlay grafts in terms of volumetric and histological changes when using different combinations of synthetic soft-type block bone and resorbable collagen membranes. MATERIALS AND METHODS: A lateral onlay graft procedure was applied at the chronic narrow alveolar ridge of the mandible in 15 beagle dogs. The groups were allocated as follows: (a) empty control; (b) onlay graft using soft-type block bone 1 (hydroxyapatite [HA]: β-tricalcium phosphate [β-TCP] = 15:85) and a non-cross-linked collagen membrane (MP-BG group); (c) onlay graft using soft-type block bone 2 (HA:β-TCP = 60:40) and a non-cross-linked collagen membrane (OC-BG group); and (d) onlay graft using soft-type block bone 1 (HA:β-TCP = 15:85) and a cross-linked collagen membrane (MP-CM group). Volumetric and histomorphometric analyses were performed at 4, 8 and 16 weeks postoperatively. RESULTS: No clinical complications occurred in any of the groups. The OC-BG group showed significantly larger total augmented volumes than the control and MP-BG groups after 8 and 16 weeks. The areas of new bone were significantly larger in the OC-BG group than the other groups at 16 weeks. The horizontal thickness of the augmented ridge was significantly larger in the OC-BG group than in the control group at 16 weeks. CONCLUSION: The OC-BG group showed superior volume maintenance and osteogenic potential for up to 16 weeks compared to the other groups in an onlay graft model of the dog mandible despite the displacement of the bone graft.

Objectives The purpose of this study was to determine the effect of administering intermittent parathyroid hormone 1-34 [teriparatide, (PTH)] on the maxillary sinus lift and bone grafting in osteoporotic rabbits induced by ovariectomy and glucocorticoid. Materials and methods Ovariectomies were performed on 20 female New Zealand white rabbits that were randomly divided into two groups: (a) the PTH group (n = 10), in which 10 μg kg-1 day-1 PTH was injected subcutaneously 5 days a week for 5 weeks (from 1 week before until 4 weeks after sinus surgery), and (b) the saline group (n = 10), in which saline substituted PTH at the same dose, mode of administration, and duration. Bone grafting with bovine bone mineral was augmented into 13 sinuses, and bone grafts and implants were simultaneously performed in seven sinuses, in both groups. Animals were sacrificed at 4 weeks after surgery. To determine whether PTH was an effective treatment for osteoporosis, we measured the bone mineral density (BMD) of the right femur using micro-computed tomography and performed radiographic and histometric analyses of the maxillary sinus surgery site. The Mann-Whitney test was used for statistical analysis. Results It was found that BMD increased in the femur, whereas none of the radiographic and histometric parameters differed significantly between the groups in the sinus, while there were large interindividual variations within groups. Conclusions These findings suggest that intermittent PTH does not promote new bone formation in the augmented maxillary sinus of ovariectomized rabbits.

Objectives There is a need of more studies on whether low primary implant stability would negatively influence the success of implant therapy. Therefore, this retrospective study analyses outcomes of implants placed with low primary stability and factors that may be related to implant failures. Material and methods This retrospective study included 156 patients, restored with 169 implants that presented manual rotation within an observed follow-up time of a minimum of 34 days and a maximum of 9.28 years. Descriptive statistics, survival analyses (life tables and Kaplan-Meier estimates) and radiographic assessment based on marginal bone level measurements were performed. This original study was adherent to STROBE guidelines. Results Seven implants failed in seven patients, rendering cumulative survival rates of 94.74% (95% CI: 89.11-97.50) and 94.33% (95% CI: 88.30-97.30) at implant and patient levels, respectively. Kaplan-Meier estimates showed implant loss was found only in advanced surgery group (7 implant loss in 82 implants) when compared with simple surgery group (no implant loss in 87 implants; p = 0.005). Conclusions Within the limitations of this retrospective study, implant placement with low primary stability might not negatively affect either the survival rates or marginal bone level changes of implants provided that a protected and unloaded healing is guaranteed.

To investigate the healing following sinus grafting in sites with a perforated schneiderian membrane repaired using a collagen membrane, compared to control sites without membrane perforation.Following elevation of the sinus membrane in 16 rabbits, each sinus was assigned to one of the following groups: (a) intentional schneiderian membrane perforation, followed by the placement of a collagen membrane and bone grafting (group SMP) and (b) bone grafting without a perforation of the schneiderian membrane and without a collagen membrane placement (control group). At 2 and 4 weeks (n = 8 for each time-point), microcomputed tomographic (micro-CT) and histomorphometric analyses were performed.Overall new bone formation in group SMP was significantly delayed compared to the control group at 2 and 4 weeks (1.58 ± 1.25% vs. 9.23 ± 2.69% at 2 weeks, 10.43 ± 3.55 vs. 17.86 ± 4.11% at 4 weeks, p 0.05). At 2 weeks, new bone formation for the areas close to lateral (1.19 ± 2.02%) and medial sinus bone walls (3.17 ± 1.98%) was markedly delayed in group SMP compared to the control group (13.08 ± 6.13% and 12.75 ± 5.63%, respectively, p 0.05), but there was no statistical difference in those areas at 4 weeks (p 0.05). The augmented volumes at 2 and 4 weeks were not statistically significantly different in both groups.The perforation of the schneiderian membrane and the repair using a collagen membrane delayed new bone formation in the augmented sinuses. However, the extension of the collagen membrane on the sinus bone walls was also attributable to this delayed bone formation.

Objectives To test whether or not one of two biological mediators (recombinant human bone morphogenetic protein-2 (rhBMP-2) and recombinant human platelet-derived growth factor (rhPDGF-BB)) is superior to the other and compared with control groups for bone regeneration around implants based on histomorphometrical outcome measures. Materials and methods Box-type defects (10 × 5 × 5 mm) were prepared on the buccal sides of the left and right edentulous ridge in ten mongrel dogs. Implants were placed at each site, the defects either received (i) bovine-derived particulated bone mineral (DBBM) mixed with rhBMP-2 and a collagen membrane (CM) (DBBM/BMP-2), (ii) DBBM mixed with rhPDGF-BB and CM (DBBM/PDGF), (iii) DBBM and CM (DBBM) and (iv) empty control (control). Animals were euthanized post-surgery at 8 weeks and 16 weeks. Histomorphometrical analyses were performed. Results The mean percentages of regenerated area within total defect area amounted to 56.95% for DBBM/BMP-2, 48.86% for DBBM/PDFG, 33.44% for DBBM and 1.59% for control at 8 weeks, and 26.79% for DBBM/BMP-2, 23.78% for DBBM/PDFG, 30.21% for DBBM and 5.07% for control at 16 weeks with no statistically significant differences between the groups (P > 0.05). The mean amount of regenerated bone was 26.97% for DBBM/BMP-2, 22.02% for DBBM/PDFG, 5.03% for DBBM and 1.25% for control at 8 weeks, and at 16 weeks, these values were lower in the two groups with biological mediators (DBBM/BMP-2 = 13.35%; DBBM/PDGF = 6.96%) and only slightly increased in group DBBM (10.68%) and the control group (4.95%) compared with 8 weeks. The first bone-to-implant contact values on the buccal side were minimal for DBBM/BMP-2 (0.57 mm) and maximal for control (3.72 mm) at 8 weeks. Conclusions The use of biological mediators (rhBMP-2 and rhPDGF-BB) can increase the amount of bone regeneration at dehiscence-type defects compared with controls at 8 weeks, but not at 16 weeks due to enhanced hard tissue remodeling processes.

Purpose The aim of this study was to radiographically compare horizontal and vertical alterations of the alveolar ridge after ridge preservation using different combinations of biomaterials. Materials and methods The patients were randomly assigned into two groups: (a) the test group, which received collagenated porcine bone plus cross-linked collagen membrane (n = 15), and (b) the control group, which received collagenated bovine bone plus non-cross-linked collagen membrane (n = 15). Cone beam computed tomography (CBCT) was performed immediately after ridge preservation and 4 months thereafter to compare the horizontal and vertical alterations of the ridge. Intention-to-treat (ITT) and per protocol (PP) analyses were performed. Results In both analyses, there was no statistically significant difference in the horizontal alteration of the alveolar ridge between the test and control groups: −1.3 ± 0.6 (ITT)/1.2 ± 0.5 (PP) vs. −1.5 ± 0.9 mm at the 1-mm level; −1.2 ± 0.7 (ITT and PP) vs. −1.2 ± 0.7 mm at the 3-mm level; and −0.9 ± 0.7 (ITT)/ −0.9 ± 0.7 (PP) vs. −0.9 ± 0.9 mm at the 5-mm level, whereas the vertical height in the midfacial area was significantly reduced in the test group compared with the control group: −-1.1 ± 2.8 (ITT)/1.5 ± 3.0 (PP) vs. −0.7 ± 1.8 mm. Conclusions The horizontal ridge alteration in ridge preservation did not differ significantly between using the test the control groups, but the vertical ridge alteration was more pronounced when using the test group (KCT0001709).

OBJECTIVES To test whether or not alveolar ridge preservation reduces vertical changes in the posterior maxilla compared to spontaneous healing following tooth extraction. MATERIALS AND METHODS Forty subjects requiring extraction of maxillary posterior teeth with root apices protruding into the maxillary sinus floor were consecutively enrolled. Patients were randomly assigned to either one of two surgical interventions: an alveolar ridge preservation procedure using collagenated bovine bone mineral and a resorbable collagen membrane (test) or no grafting (control). Cone-beam computed tomographies were taken immediately and at 6 months after surgery, prior to dental implant placement. RESULTS Based on radiographic data, the level of the sinus floor remained stable over time (baseline to 6 months) in the test group (-0.14 mm [-0.31, -0.02]). In the control group, the sinus floor level shifted more coronally (-1.16 mm [-1.73, -0.61]) than the test group (p

Objective To evaluate in vitro the changes in implant surface topography and roughness of commercial implants after instrumentation with five decontamination protocols. Material and methods Seventy-two titanium implants with a sandblasted and acid-etched (SLA) surface were placed 5 mm supra-crestally. Five groups of twelve implants were instrumented with the following protocols: a metal scaler tip (SCAL), a thermoplastic scaler tip (PEEK), a round titanium brush (RBRU), a tufted brush with titanium bristles (TNBRU), and a glycine-based air-powder abrasive (GLYC). A sixth group with untreated implants was used as control. Scanning electron microscope and confocal laser scanning microscope were utilized to evaluate the changes in the implant surfaces. Results The SCAL caused pronounced macroscopic alterations and damage of the implant surface, the PEEK left remnants of the plastic tip in the implant surface, and both titanium brush groups flattened the thread profile, while minimal alterations were observed in the GLYC. When compared to the control group, the roughness parameters (Sa) in the buccal aspect increased in the thread area of SCAL, and a minor reduction was observed in the PEEK while in the other groups, these values remained unchanged. In the valley areas, however the RBRU, TNBRU, and GLYC experienced a significant reduction (smoothening) indicating different accessibility of the decontamination protocols to the thread and valley. Similarly, the buccal aspects had more pronounced changes than those in the palatal aspect. Conclusion Within the limitations of this in vitro investigation, the tested protocols induced different macroscopic alterations and surface roughness changes that varied in the thread and valley area.

Objective The aim of this pilot study was to test whether a porcine collagenated bone substitute block (PCBB) and collagen membrane (CM) loaded with bone morphogenetic protein-2 (BMP-2) used for horizontal ridge augmentation differ from PCBB and CM without BMP-2 regarding the osseointegration of the grafting material and the maintenance of the ridge contour. Material and methods Two semi-saddle bone defects were created in each side of the mandible of six dogs. The defects were randomly allocated to receive one of the following treatments: bone augmentation using (1) PCBB, (2) PCBB loaded with BMP-2 (PCBB-BMP2), (3) PCBB + CM and (4) PCBB + CM loaded with BMP-2 (PCBB + CM-BMP2). After 12 weeks, one titanium implant was inserted into every site. After 8 weeks, one central histological section of each site was prepared. Histomorphometrical assessments were performed evaluating the augmented area (AA), the area of new bone (NB) (primary outcome), residual bone substitute (BS) and non-mineralized tissue (NMT) within AA in mm2. In addition, the most coronal and the most buccal localizations of new bone and residual bone substitute, and the most coronal bone-to-implant contact were measured in mm. Results Clinically, all PCBB were firmly integrated and permitted implant placement. All the implants osseointegrated and exhibited complete hard-tissue coverage of the buccal surface. Bone ingrowth always reached the central portions of PCBB. AA measured 10.4 ± 4.2 mm2 for PCBB, 11.8 ± 2.8 mm2 for PCBB-BMP2, 9.8 ± 2.9 mm2 for PCBB + CM and 8.5 ± 2.2 mm2 for PCBB + CM-BMP2. Only the difference between PCBB-BMP2 and PCBB + CM-BMP2 was statistically significant (P = 0.031). NB reached 2.3 ± 1.3 mm2 for PCBB, 2 ± 0.5 mm2 for PCBB-BMP2, 2.7 ± 1.2 mm2 for PCBB + CM and 1.8 ± 0.7 mm2 for PCBB + CM-BMP2. There were no statistically significant differences regarding NB, the most coronal and the most buccal localizations of new bone, residual bone substitute and bone-to-implant contact (P > 0.05). Conclusions The addition of BMP-2 to PCBB or CM used for horizontal ridge augmentation did not render a statistically significant improvement in the maintenance of the augmented ridge contour and the new bone formation. PCBB with and without CM showed pronounced bone ingrowth and capacity to maintain the augmented ridge contour. In all the regions previously augmented with PCBB, the implants successfully integrated and presented with complete hard-tissue coverage.

Aims The objectives of this study were to evaluate bone regeneration beneath a newly devised bone substitute combined with collagen membrane (called a bone patch) lying over a concomitantly placed mini-implant following sinus floor elevation and verify its usefulness as a carrier system for recombinant human bone morphogenetic protein-2 (rhBMP-2) in rabbits. Materials and methods The sinus floor elevation procedure was performed bilaterally in five rabbits. Either a plain bone patch (control group) or an rhBMP-2-loaded patch (experimental group) was randomly placed beneath the elevated sinus membrane (SM) of both sinuses, where the mini-implants were concomitantly placed. Micro-computed tomographic and histologic analyses were performed at 4 weeks post-surgery. Results In micro-computed tomography, the median values of the total augmented volume and the mineralized bone volume were significantly higher in the experimental group than in the control group (161 vs. 122 mm3 [P

Objectives The aim of this study was to evaluate the hybrid technique, which was modified from the lateral approach in sinus elevation by combining transalveolar access. Materials and methods Sixty patients (mean age of 53.3 ± 11.6 years) with 105 implants placed in the posterior maxilla with the average remaining bone height (RBH) of 4.3 ± 1.8 mm (range of 1.2–9.2 mm) were enrolled in the hybrid group and followed up for 96 months. The control group included 36 patients with 44 implants placed in the corresponding site with sufficient RBH. Cumulative survival rate (CSR), radiographic measurements in RBH, augmented bone height (ABH), and marginal bone loss (MBL) were analyzed during the follow-up period. Results Cumulative survival rate in the hybrid group was 98.1%, which was comparable to the control group (97.7%). MBL of the mesial and distal aspects in the hybrid group (0.28 ± 0.66 mm and 0.41 ± 0.93 mm, respectively) was comparable to the control group (0.84 ± 1.11 mm and 0.76 ± 0.88 mm, respectively). In the hybrid group, the membrane perforation rate during the surgery was 4.5%. ABH was 8.3 ± 1.8 mm after the surgery and maintained consistently during the follow-up period (7.4 ± 1.9 mm after 4 years). Conclusion The hybrid technique is a simple and predictable surgical method for simultaneous placement of a dental implant with sinus floor elevation regardless of the RBH.

OBJECTIVES The aim of this retrospective study was to determine the clinical and the radiographic outcomes of dental implants placed in elderly people older than 65 years. MATERIALS AND METHODS In total, 902 implants in 346 patients (age: 65-89 years) were followed up for 2-17 years following the implant surgery. The survival rate of these implants was recorded and analyzed. Changes in marginal bone levels were also analyzed in serial radiographs, and Cox regression analysis for implant loss was performed. RESULTS The survival rates were 95.39% and 99.98% in the implant- and patient-based analyses, respectively (involving a total of 29 implant failures), and the marginal bone loss at the implants was 0.17 ± 0.71 mm (mean ± SD). The number of failures was greatest in patients aged 65-69 years. The Cox regression with shared frailty analysis showed that implant loss was significantly greater in those aged 65-69 years than in those aged 70-74 years (P

OBJECTIVE To histologically and radiographically evaluate soft (primary outcome) and hard tissue integration of two-piece titanium and zirconia dental implants with/without buccal dehiscence defects. MATERIALS & METHODS In six dogs, five implants were randomly placed on both sides of the mandible: (a) Z1: a zirconia implant (modified surface) within the bony housing, (b) Z2: a zirconia implant (standard surface) within the bony housing, (c) T: a titanium implant within the bony housing, (d) Z1_D: a Z1 implant placed with a buccal bone dehiscence (3 mm in height, identical width to implant body), and (e) T_D: a titanium implant placed with a buccal bone dehiscence. Two weeks of healing and 6 months of loading were applied on each hemi-mandible, respectively. RESULTS The median level of the margo mucosae shifted more apically over time in all groups (borderline statistical significance in groups Z1_D: -0.52 mm and T_D: -1.26 mm). The median height of the peri-implant mucosa in groups Z1_D and T_D was greatest at 2 weeks and 6 months, but the linear change in the peri-implant mucosa was statistically significant only for group T_D over time (-1.45 mm). Z1 demonstrated a higher bone-to-implant contact compared to Z2 and T. Minimal change of radiographic marginal bone levels in all groups was observed (

AIM The aim of this experimental in vivo investigation was to assess the anti-resorptive effect of low concentration pamidronate on the buccal plate in fresh extraction sockets. MATERIALS AND METHODS The distal roots of the third premolars were extracted bilaterally in six dogs. A collagen matrix loaded with either pamidronate (test group) or saline (control group) was positioned on the outer surface of buccal bone immediately after tooth extraction and subsequently covered with a coronally advanced flap. Histological and histomorphometric outcomes were evaluated 12 weeks later. RESULTS The mean vertical distance between the buccal and lingual bone crest differed significantly between the test and control groups (0.52 ± 0.43 and 2.21 ± 1.15 mm, respectively; p = .037). The width of the buccal bone 1 mm below the crest was significantly wider in the test group than the control group (4.68 ± 0.68 vs. 3.44 ± 0.60 mm, p

Objectives This study compared the efficacies of different layered approaches using autogenous bone and synthetic bone substitute for ridge augmentation on implant dehiscence defects in dogs. Materials and methods Right mandibular second, third, and fourth premolars and the first molar were extracted, followed by standardized one-wall defect preparation in five dogs. After a healing period of 12 weeks, three implants (Implantium®) were installed. Each of the three implant dehiscence defects was grafted with a different material as follows: (i) synthetic bone substitute combined with collagen (SBC; SBC group), (ii) inner autogenous bone layer and outer SBC layer (IAB group), and (iii) inner SBC layer and outer autogenous bone layer (OAB group). The grafted sites were covered with a resorbable collagen membrane. Quantitative and qualitative analyses of the subsequent bone regeneration were performed at 12 weeks postoperatively. Results The dome-like augmented shape was relatively well maintained in the IAB and OAB groups, while the graft particles in the SBC group were dispersed. The bone-to-implant contact values tended to be significantly higher in the OAB group (49.51%) than in the SBC (36.58%) group. The amounts of newly formed bone within an area designated as 1 × 3 mm (width × height) from the implant platform in the IAB, OAB, and SBC groups were 35.59%, 28.10%, and 16.71%, respectively. Conclusion Application of the layered approach using autogenous bone and synthetic biomaterial resulted in substantial new bone formation and volume maintenance on implant dehiscence defects, irrespective of the position of the autogenous bone layer.

Objectives The aim of the study was to elucidate the efficacy of bone regeneration at the early stage of healing in rabbit sinuses grafted with a biphasic calcium phosphate (BCP) carrier soaked in a high concentration of recombinant human bone morphogenetic protein-2 (rhBMP-2). Materials and methods Both maxillary sinuses of eight male rabbits were used. The sinus on one side (assigned randomly) was grafted with BCP loaded with rhBMP-2 (1.5 mg/ml; test group) using a soaking method, while the other was grafted with saline-soaked BCP (control group). After a 2-week healing period, the sinuses were analyzed by micro-computed tomography and histomorphometry. Results The total augmented area and soft tissue space were significantly larger in the test group than in the control group, whereas the opposite was true for the area of residual material and newly formed bone. Most of the new bone in the test group was localized to the Schneiderian membrane (SM), while very little bone formation was observed in the window and center regions of the sinus. New bone was distributed evenly in the control group sinuses. Conclusion Within the limitations of this study, it appeared that application of a high concentration of rhBMP-2 soaked onto a BCP carrier inhibited bone regeneration from the pristine bone and increased soft tissue swelling and inflammatory response at the early healing stage of sinus augmentation, although osteoinductive potential was found along the SM.

Objectives This study compared the bone regenerative effects of a recombinant human bone morphogenetic protein 2 (rhBMP-2)-loaded collagen-based biphasic calcium phosphate composite (BCPC) and rhBMP-2-loaded biphasic calcium phosphate (BCP). Material and methods The in vitro release profiles of rhBMP-2-loaded BCP and BCPC were measured. The animal surgery was performed on ten rabbits. Four 8-mm-diameter circular calvarial defects were made and filled with BCP, BCPC, rhBMP-2-loaded BCP (BMP + BCP) and rhBMP-2-loaded BCPC (BMP + BCPC). The animals were euthanized either 2 or 8 weeks after surgery. Results The initial burst release of rhBMP-2 was greater for BCP than for BCPC, and both presented a slow release pattern thereafter. In rabbit calvarial defects, the space maintaining capability and graft resorption of all experimental groups did not show statistical differences at 2 and 8 weeks. New bone formation in the rhBMP-2-loaded groups was greater than in the non-loaded groups at both weeks, but the amount of new bone was comparable between both rhBMP-2-loaded groups at both weeks. There was a distinct histologic difference between the BMP + BCP and BMP + BCPC groups at 2 weeks; the new bone formation occurred more in the intergranular spaces and the BCP-to-bone contact was greater in the BMP + BCPC group, but these differences were no longer discernible at 8 weeks. Conclusions BCP- and BCPC-loaded rhBMP-2 significantly improved bone regeneration and BCPC led to a dense network of new bone and bone particles during the early healing period. BCPC can therefore be considered as a promising candidate for carrying rhBMP-2.

OBJECTIVES The aim of the study was to test whether or not the use of a polyethylene glycol (PEG) hydrogel with or without the addition of an arginylglycylaspartic acid (RGD) sequence applied as a matrix in combination with hydroxyapatite/tricalciumphosphate (HA/TCP) results in similar peri-implant bone regeneration as traditional guided bone regeneration procedures. MATERIAL AND METHODS In 12 beagle dogs, implant placement and peri-implant bone regeneration were performed 2 months after tooth extraction in the maxilla. Two standardized box-shaped defects were bilaterally created, and dental implants were placed in the center of the defects with a dehiscence of 4 mm. Four treatment modalities were randomly applied: i)HA/TCP mixed with a synthetic PEG hydrogel, ii)HA/TCP mixed with a synthetic PEG hydrogel supplemented with an RGD sequence, iii)HA/TCP covered with a native collagen membrane (CM), iv)and no bone augmentation (empty). After a healing period of 8 or 16 weeks, micro-CT and histological analyses were performed. RESULTS Histomorphometric analysis revealed a greater relative augmented area for groups with bone augmentation (43.3%-53.9% at 8 weeks, 31.2%-42.8% at 16 weeks) compared to empty controls (22.9% at 8 weeks, 1.1% at 16 weeks). The median amount of newly formed bone was greatest in group CM at both time-points. Regarding the first bone-to-implant contact, CM was statistically significantly superior to all other groups at 8 weeks. CONCLUSIONS Bone can partially be regenerated at peri-implant buccal dehiscence defects using traditional guided bone regeneration techniques. The use of a PEG hydrogel applied as a matrix mixed with a synthetic bone substitute material might lack a sufficient stability over time for this kind of defect.

Objectives The objective of this study was to determine the effect of bone morphogenetic protein‐2 (BMP‐2) mixed with either polyethylene glycol hydrogel or synthetic bone substitute (SBS) on new bone formation in peri‐implant dehiscence defects after 16 weeks of healing. Materials and methods A guided bone regeneration procedure was performed in box‐type peri‐implant defects that were surgically prepared in six beagle dogs. The following four experimental groups were used (i) control (no graft), (ii) SBS+hydrogel, (iii) SBS+BMP‐2/hydrogel and (iv) BMP‐2/SBS+hydrogel. Volumetric analysis using micro‐computed tomography and histomorphometric analysis was performed at 16 weeks post‐operatively. Results The amount of new bone and the total augmented volume did not differ significantly between both BMP‐treated groups and the SBS+hydrogel group (p > .05). Likewise, no histometric differences were observed in the values of new bone area and bone‐to‐implant contact ratio among the three augmentation groups (new bone area: 0.06 ± 0.08, 0.19 ± 0.20, 0.48 ± 0.37 and 0.56 ± 0.60 mm2 [mean ± standard deviation] in groups 1–4, respectively; bone‐to‐implant contact: 9.44 ± 11.51%, 19.91 ± 15.19%, 46.31 ± 29.82% and 42.58 ± 26.27% in groups 1–4, respectively). Conclusion The osteogenic efficacy of BMP‐2 on the regeneration of peri‐implant bone defects was not detectable after 16 weeks regardless of the carrier materials.

Objectives This study evaluated the reosseointegration of implants that had been reinserted following the mechanical disintegration of immature osseointegration in dogs. Materials and methods Rotationally mobile implants were installed into an oversized drill space in five canine mandibles. After a healing period of 4 weeks, the immature osseointegration of the implant was intentionally disintegrated by the application of a mechanical countertorque and then reinserted at the same site (experimental group); in the control group, the mobile implant remained submerged without any surgical intervention. The animals were euthanized 4 weeks after the disruption of osseointegration. Changes in the implant stability quotient (ISQ) and Periotest value (PTV) were analyzed, and the bone-implant contact (%) was measured histometrically. Results All experimental and control sites showed successful mechanical stability at 8-week healing period. The mean ISQ was significantly higher in the experimental group than in the control group at 8 weeks (P

OBJECTIVES The objective of this experiment was to test whether or not a synthetic bone substitute (SBS) was more effective than a polyethylene glycol hydrogel as a carrier material for bone morphogenetic protein-2 (BMP-2) when attempting to regenerate bone. MATERIAL AND METHODS Two identical, box-type dehiscence defects (4 × 4 mm buccolingually and apicocoronally, and 8 mm mesiodistally) were surgically prepared on buccal sides of the left and right edentulous ridge in five beagle dogs. Following implant placement, the defects either received (i) no graft, (ii) SBS+hydrogel, (iii) SBS+BMP-2 loaded hydrogel, and (iv) BMP-2-loaded SBS+hydrogel. The animals were euthanized at 8 weeks postsurgery. Radiographic and histomorphometric analyses were performed. RESULTS The hydrogel alone was not able to stabilize the grafted bone particles at 8 weeks, and SBS+hydrogel group did not significantly differ from the control group in all volumetric measurements. On the other hand, extensively regenerated new bone was connected with most of the remaining SBS particles in the BMP-2 groups. The BMP-2 groups exhibited significantly greater new bone formation (10.65 mm(3) and 1.47 mm(2) in the SBS+BMP-2-loaded hydrogel group; 14.17 mm(3) and 0.93 mm(2) in the BMP-2-loaded SBS+hydrogel) than non-BMP-2 groups (1.27 mm(3) and 0.00 mm(2) in the control group; 2.01 mm(3) and 0.19 mm(2) in the SBS+hydrogel group) in volumetric and histomorphometric analyses (P

Objectives The objective of this study was to elucidate the socket healing process and biodegradation of incorporating synthetic bone fillers followed by grafting of the fresh extraction socket. Materials and methods Third premolars in four quadrants of eight beagle dogs were extracted and randomly treated with either one of hydroxyapatite (HA), biphasic calcium phosphate (BCP), β-tricalcium phosphate (β-TCP), or no graft (C). Histologic observations and histomorphometric analysis at three zones (apical, middle, and coronal) of the socket were performed. Socket area (S) and the proportions of newly formed bone (%NB), residual biomaterials (%RB), and fibrovascular connective tissue (%FCT) at 2, 4, and 8 weeks were measured. The numbers of osteoclast-like multinucleated cells (No.OC) were also determined at the three zones. Results %NB was significantly higher in control group compared with the grafted groups at all healing periods. %NB of HA and BCP increased with time, whereas %RB showed different patterns that decreased in BCP, unlike the minimal change observed in HA. %NB of β-TCP showed smallest portion compared with other grafted groups at 2 and 4 weeks, however, significantly increased at 8 weeks. %RB of β-TCP was less than HA and BCP at all healing periods. Numbers of multinucleated cells were greater in BCP and β-TCP, followed by HA and smallest in control group. Conclusions Within the limit of this study, bone formation of the extraction socket was delayed in the sockets grafted with synthetic bone fillers and showed different healing process according to the biodegradation patterns.

OBJECTIVE The objectives of this study were to analyze retrospectively the long-term survival and success rates of Narrow implants (NIs) placed with various implant systems, and the association with biological and technical complications. MATERIAL AND METHODS In total, 338 patients (men = 45.6%, women = 54.4%) who received 541 NIs (≤3.5 mm in diameter) for fixed prostheses were enrolled in this retrospective study. The mean marginal bone level (MMBL) change was calculated. Life table analysis with the cumulative survival rate and success rate was calculated, and biological and technical complications were evaluated. RESULTS The annual MMBL change was 0.07 ± 0.20 mm. The 12-year cumulative survival (success) rates of NIs were 98.1% (91.8%) and 98.5% (93.8%) for the implant- and subject-based analysis, respectively. During the observation period up to 12 years (mean 4.9 years), six implants were lost in the maxilla, whereas three implants were lost in the mandible. Technical complications were more frequent than biological complications. Infection was the most common underlying cause of biological complications and the most frequent technical complication was decementation. CONCLUSION In conclusion, the findings of this study suggest that NIs could be used safely for narrow alveolar ridges or narrow mesiodistal spaces on the basis of their high survival rate.

Objectives To histomorphometrically analyze bone formation on amorphous calcium phosphate (ACP), micro-macroporous biphasic calcium phosphate (MBCP), and freeze-dried bone allograft (FDBA) in three-wall defects adjacent to structured surface with calcium phosphate nanocoating implants in dogs. Materials and methods Five male mixed-breed dogs were used in this study. The premolars and molars were extracted on both sides of the mandible. Eight weeks after extraction, four implants were submerged on each side of the mandible. Three-wall intrabony defects (5 × 3 × 3 mm) were surgically created adjacent to the implants before installation. No grafts were placed in the control group. At the experimental sites, each intrabony defect was grafted with either ACP, MBCP, or FDBA. The dogs were sacrificed after 12 weeks, and histological and histomorphometrical analyses of the implant sites were performed. Results All of the three experimental groups exhibited defect resolution and osseointegration that showed a statistically significant difference compared with the control group in terms of remaining defect depth and bone-to-implant contact (BIC). However, there were no statistical significances among the three experimental groups. MBCP had the highest BIC (63.57 ± 21.57%), followed by ACP and FDBA. The control group showed the least bone area and the greatest remaining defect depth. Conclusion Grafts with the synthetic biomaterials ACP and MBCP showed bone regeneration that was similar to FDBA in surgically created three-wall intrabony defects adjacent to implants. Within the limitations of this study, it can be concluded that ACP and MBCP synthetic biomaterials are as effective as FDBA at osteoconduction.

Objectives: This study evaluated both the clinical and histological aspects of bone formation in maxillary sinus augmentation using MBCP as the bone-grafting material. Material and methods: MBCP was used as a primary bone substitute for maxillary sinus augmentation. Fifty-two patients were selected after a medical and dental examination, and were divided into the following three groups: those augmented with MBCP only; MBCP combined with irradiated cancellous bone; and MBCP combined with intraoral autogenous bone. After a healing period (average 6.78 months after surgery), bone cores were harvested for a histological evaluation and the implant fixtures were installed. These bone cores were evaluated via light microscope and implants were followed up for at least six months after loading. Results: Four to ten months after surgery, new vital bone surrounding the MBCP particles was observed in 18 bone biopsies. Two out of the 130 implants installed were explanted due to a failure of osseointegration before the prosthetic procedure. All the remaining implants were functioning for 6 to 27 months (average 12.96 months). The cumulative survival rate of the implants was 98.46%. Conclusion: These results show that MBCP can be used as a grafting material for sinus floor augmentation, whether combined with other bone graft materials or not, and lead to a predictable prognosis for dental implants in the posterior maxillary area where there is insufficient vertical height for fixture installation.

OBJECTIVES The aim of this study was to observe the sequential healing of onlay grafts in terms of the volumetric and histologic changes using different bone substances and absorbable membranes according to the presence of collagen cross-linking. MATERIAL AND METHODS Four groups involving onlay grafting with different materials were randomly assigned to both sides of the maxillae of 15 beagle dogs: (i) control group without any treatment; (ii) group NN, bovine hydroxyapatite incorporated into a non-cross-linked collagen matrix (BHC) + non-cross-linked collagen membrane (NCCM); (iii) group NC, BHC + cross-linked collagen membrane (CCM); and (iv) group CC, porcine hydroxyapatite incorporated into a cross-linked collagen matrix + CCM. Radiographic and histological analyses were performed after three different healing periods: 4, 8 and 12 weeks. RESULTS At week 4, the bone substances were well localized under the barrier membrane in groups NC and CC, while the bone substances became spread out and flattened in group NN. Similarly, the augmented height was significantly greater in groups NC and CC (2.55 and 2.51 mm, respectively; median) than in group NN (1.96 mm, P

The aim of this study was to determine the de novo bone formation beneath the Schneiderian membrane supported by an implant and with the adjunctive use of a hydroxyapatite-powdered collagen (HAC) membrane without bone grafting in rabbit sinuses.After sinus-floor elevation procedure, an experimentally devised mini-implant (4 mm in length and 3 mm in diameter) was placed in eight rabbits. For the experimental group, an HAC membrane was placed onto the elevated sinus mucosa prior to implant placement. The animals were allowed a healing period of either 4 or 8 weeks. Microcomputed tomography and histologic analyses were performed.All implants placed at the thin lateral bony wall were histologically osseointegrated. The topography of the newly formed bone appeared to slope gently from the medial side down to the lateral side. The volume of new bone was significantly greater in the experimental group than in the control group at 4 weeks (P0.05), but not at 8 weeks. However, none of the samples in the two groups was entirely covered to the apex by bone tissue.It can be concluded that using the HAC membrane in combination with placement of an implant resulted in substantial bone formation around the implant, which might have been influenced by the proximity of the axial bony wall.

To evaluate the bone regenerative effect of bioresorbable collagen membrane (CM) as a carrier for recombinant human bone morphogenetic protein-2 (rhBMP-2) when performing lateral onlay grafts using bovine hydroxyapatite incorporated with collagen matrix (BHC) in combination with CM in dogs.A guided bone regeneration (GBR) was performed at the buccal aspect of edentulous maxillary alveolar ridges in dogs (n = 5): (1) BHC group, in which rhBMP-2-loaded BHC was covered by a CM, and (2) CM group, in which BHC was covered by an rhBMP-2-loaded CM. A histologic and histometric analysis was performed after 8 weeks of healing.Both the BHC and CM groups exhibited substantial newly formed bone (NB). More NB was found in the CM group than in the BHC group without statistical significance. Most of the NB was in direct contact with the residual bone substitute in the BHC group, whereas the projections and islands of NB were observed in the spaces between the residual bone substitute clusters in the CM group. The bone-to-residual bone substitute contact ratio was significantly lower in the CM group than in the BHC group (P = 0.043).Within the limitations of this study, it can be concluded that rhBMP-2-loaded CM performed lateral onlay grafts as effectively as rhBMP-2-loaded BHC while showing less bone-residual bone substitute contact ratio in dogs. The loading of CMs with rhBMP-2 might therefore be a recommendable treatment option for facilitating lateral onlay graft combined with rhBMP-2.

Objectives The objective of this study was to evaluate the secondary stability of microthickness hydroxyapatite (HA)-coated implants placed without primary stability in dogs. Materials and methods A total of 48 implants were placed in six dogs. The groups were divided according to the absence or presence of primary stability and healing periods (4 and 8 weeks). Two implants for histological analysis and removal torque test in experimental group were placed without primary stability, showing rotational movement. The other two implants in control group were placed with primary stability. Mechanical test values and histometric measurements were analyzed. Results The experimental group showed significant increase in a time-dependent manner, while the mean values of the control group were constant in the mechanical tests. The HA layer remained intact, and substantial bone fragments were attached on the surface of the retrieved implant. All implants appeared to be in intimate contact with the host bone and without any inflammation after both 4 and 8 weeks of healing in histology. Conclusion The HA-coated implants exhibited mechanically and histometrically comparable osseointegration after 4 weeks of healing, regardless of primary stability, and the HA-coating layer demonstrated high resistance to exfoliation.

Objective The purpose of this study was to evaluate the osseointegration of two different types of surfaces, smooth and roughened surface implants nanocoated with calcium phosphate (CAP) around different bone environment. Materials and methods Five male mongrel dogs were used in this study. The premolars and molars were extracted on both sides of the mandible. Eight weeks after extraction, implants were submerged on both sides of the mandible. On the left, CAP nanocoated roughened surface (RCAP) implants were installed whereas, the CAP nanocoated smooth surface (SCAP) implants were installed on the right side. The control group had no defect, on the other hand, three-wall intrabony defects were surgically created adjacent to the implant in the experimental group. The dogs were sacrificed after 12 weeks. Results Histological and histomorphometrical analysis were performed with the specimen. The SCAP and RCAP implants showed good osseointegration with no statistical significance in the control group. Histologically, the SCAP group showed little resolution of the defect compared with the RCAP group. In the experimental groups, there was a significant difference in defect fill between SCAP and RCAP. Conclusion Within the limits of our study, it can be concluded that SCAP and RCAP implants show no difference in sufficient bone area whereas, CAP nanocoating on roughened implant surface may enhance osseointegration in deficient bone environment.

This study evaluated radiographically the integration and volume maintenance of grafted autogenous block bone under various cortical bone perforation conditions in dogs.Five mongrel dogs were used. Each dog received four differently prepared onlay block bone grafts: a solid block graft was fixed on either (1) a cortically perforated recipient bed (SGPR) or (2) a nonperforated recipient bed (SGNPR), a perforated block graft was fixed on either (3) a nonperforated recipient bed (PGNPR) or (4) a cortically perforated recipient bed (PGPR). The animals were sacrificed at 1 day, 4 days, 10 days, 4 weeks, and 8 weeks after surgery. Specimens were prepared and radiographic analysis was conducted by using micro-computed tomography. The residual bone volume (RBV; mm(3) ), cross-sectional bone area (BA; mm(2)), and residual height (RH; %) of the grafted block bone were measured radiographically.The interface between the recipient bed and the graft showed no signs of bone integration at 1, 4, and 10 days of healing. However, at 4 weeks of healing, bone integration was observed in all groups. The RBV, BA, and RH of the grafts gradually decreased by 4 weeks of healing. At 8 weeks, the PGPR condition exhibited a higher RBV, BA, and RH than the other conditions, whereas the SGNPR condition exhibited the lowest RBV, BA, and RH.Within the limitations of this study, it can be concluded that intentional cortical perforation on the recipient bed and block bone graft may influence volume maintenance of the graft.

Objectives The purpose of this study was to elucidate the healing pattern of sand-blasted, large grid, acid-etched (SLA)-surfaced implants at two healing periods in a model that represents loosened implants (LIs) installed without mechanical engagement. Material and methods Five mongrel dogs were used, in which 20 dental implants were prepared. The implants were divided into two groups according to the absence or presence of initial mechanical engagement: LIs) and control, respectively. An oversized drill was used to prepare the implant area for the LI group. The implants were allowed to heal for 4 or 8 weeks. After the healing period, the experimental animals were sacrificed and block sections were obtained for histological analysis and histometric measurements. Results All implants were in intimate contact with the host bone and were without any inflammation after both 4 and 8 weeks of healing. While the mean amount of bone-to-implant contact (BIC) was constant in the control group, it tended to increase in the LI group with increasing healing period. However, neither BIC nor bone density differed significantly between the groups or with the healing period. Conclusion From the results of the study, it can be conjectured that the submerged and unloaded SLA-surfaced implants could result in successful osseointegration, even if the mechanical engagement was not obtained at placement of the implants.

To evaluate the effect of vertical and periosteal-releasing incisions (PRI) on the extension of the buccal flap in a trapezoidal flap design.Thirty patients scheduled for implant surgery accompanied by bone augmentation were recruited. The amount of flap extension pulled with a minimal tension of 5 g using a dynamometer was measured before and after the first and the second vertical incisions (VI) and PRI. The results were compared based on gender, surgical site and operator's experience.The first VI extended flap length by 1.1 ± 0.6 mm, 113.4% more compared with the original flap length. The second VI increased flap length by 1.9 ± 1 mm (124.2%), and the PRI significantly extended flap length by 5.5 ± 1.5 mm (171.3%) (P0.001). The length of the first and the second VI and the amount of flap extension by each incision were compared, and there were no statistically significant differences between gender, surgical site (maxilla vs. mandible) and operator's experience (faculty vs. residents).Vertical and PRI in a trapezoidal flap design can be successfully utilized to attain tension-free primary closure during implant or periodontal surgeries. However, the PRI appears to be the only determinant key factor that can significantly extend the length of the flaps, while host- and operator-related factors might not have any significant effect on such flap extension.

Objectives: This study evaluated radiographically the integration and volume maintenance of grafted autogenous block bone under various cortical bone perforation conditions in dogs. Material and methods: Five mongrel dogs were used. Each dog received four differently prepared onlay block bone grafts: a solid block graft was fixed on either (1) a cortically perforated recipient bed (SGPR) or (2) a nonperforated recipient bed (SGNPR), a perforated block graft was fixed on either (3) a nonperforated recipient bed (PGNPR) or (4) a cortically perforated recipient bed (PGPR). The animals were sacrificed at 1 day, 4 days, 10 days, 4 weeks, and 8 weeks after surgery. Specimens were prepared and radiographic analysis was conducted by using micro-computed tomography. The residual bone volume (RBV; mm3), cross-sectional bone area (BA; mm2), and residual height (RH; %) of the grafted block bone were measured radiographically. Results: The interface between the recipient bed and the graft showed no signs of bone integration at 1, 4, and 10 days of healing. However, at 4 weeks of healing, bone integration was observed in all groups. The RBV, BA, and RH of the grafts gradually decreased by 4 weeks of healing. At 8 weeks, the PGPR condition exhibited a higher RBV, BA, and RH than the other conditions, whereas the SGNPR condition exhibited the lowest RBV, BA, and RH. Conclusion: Within the limitations of this study, it can be concluded that intentional cortical perforation on the recipient bed and block bone graft may influence volume maintenance of the graft. To cite this article: Oh K-C, Cha J-K, Kim C-S, Choi S-H, Chai J-K, Jung U-W. The influence of perforating the autogenous block bone and the recipient bed in dogs. Part I: a radiographic analysis. Clin. Oral Impl. Res. 22, 2011; 1298–1302. doi: 10.1111/j.1600-0501.2010.02110.x

To histomorphometrically analyze bone formation on amorphous calcium phosphate (ACP), micro-macroporous biphasic calcium phosphate (MBCP), and freeze-dried bone allograft (FDBA) in three-wall defects adjacent to structured surface with calcium phosphate nanocoating implants in dogs.Five male mixed-breed dogs were used in this study. The premolars and molars were extracted on both sides of the mandible. Eight weeks after extraction, four implants were submerged on each side of the mandible. Three-wall intrabony defects (5 × 3 × 3 mm) were surgically created adjacent to the implants before installation. No grafts were placed in the control group. At the experimental sites, each intrabony defect was grafted with either ACP, MBCP, or FDBA. The dogs were sacrificed after 12 weeks, and histological and histomorphometrical analyses of the implant sites were performed.All of the three experimental groups exhibited defect resolution and osseointegration that showed a statistically significant difference compared with the control group in terms of remaining defect depth and bone-to-implant contact (BIC). However, there were no statistical significances among the three experimental groups. MBCP had the highest BIC (63.57 ± 21.57%), followed by ACP and FDBA. The control group showed the least bone area and the greatest remaining defect depth.Grafts with the synthetic biomaterials ACP and MBCP showed bone regeneration that was similar to FDBA in surgically created three-wall intrabony defects adjacent to implants. Within the limitations of this study, it can be concluded that ACP and MBCP synthetic biomaterials are as effective as FDBA at osteoconduction.

This study was conducted to evaluate the healing of surgically created circumferential gaps around non-submerged-type implants according to varying size and healing periods in dogs.In four mongrel dogs, all mandible premolars were extracted and after an 8-week healing period, non-submerged-type implants were placed. Circumferential coronal defects around the implants were performed surgically with a customized tapered step drill. Groups were divided according to the width of the coronal gaps: 1, 1.5, or 2 mm. First the right side of the mandible was prepared, and after 8 weeks, the left side was prepared. The dogs were sacrificed following an 8-week healing period. Specimens were analyzed histologically and histomorphometrically.As the size of the coronal gap increased, the unfilled area tended to be greater. In terms of bone-to-implant contact and bone density, both the 1 and 1.5 mm groups showed a larger percentage of coronal defect than the apical side, while the 2 mm group showed contrary results in the 8-week groups. The general histologic features in the 16-week groups were similar to the findings of 8-week groups but were more matured, with a higher percentage of lamellar bone. A certain amount of bone filling and osseointegration was observed in the defects of all the groups.It can be concluded that the remaining defect, small enough to be clinically neglected, irrespective of gap size within 2 mm, does not need any kind of regenerating procedures.

Publisher's version (útgefin grein), Objectives: The aim of the present superiority study was to determine the effect of systemic antibiotics primarily on patient-reported outcome measures (PROMs) and post-surgical complications in patients undergoing oral implant therapy with simultaneous guided bone regeneration (GBR). Materials and Methods: A total of 236 medically and periodontally healthy patients received oral implants with simultaneous GBR at seven centres. Pre-operative antibiotics of 2 g amoxicillin were prescribed to the test group 1 hr prior to surgery and 500 mg thrice daily on days 1–3 after surgery. The control group was given a placebo. Group allocation was performed randomly. Primary outcome variables were PROMs recorded as visual analogue scale scores assessed on days 1–7 and 14 on pain, swelling, haematoma and bleeding. Post-operative complications as secondary outcome variables were examined at 1, 2, 4 and 12 weeks from surgery. Chi-square tests and repeated measures of analysis of variance (ANOVA) were performed for statistical evaluation. Results: No statistically significant differences (p >.05) between the two groups were detected for the evaluated PROMs. The same was noted with respect to post-surgical complications. Four implants were lost—three in the test group and one in the control group. Conclusion: In this trial, systemic antibiotics did not provide additional benefits to PROMs, nor the prevention of post-surgical complications in medically and periodontally healthy patients undergoing oral implant therapy with simultaneous GBR. However, further studies with larger sample sizes are still required to support the clinical outcomes of this study., This study has been supported by a research grant of the ITI Foundation (ITI Grant‐No: No. 962_2013). Further, we want to thank the Geistlich AG, Wolhusen, Switzerland, for providing bone substitutes and collagen membranes (Bio‐Oss® and Bio‐Gide®); Medochemie Limassol, Cyprus, for providing the study medication; and the Straumann AG (Basel, Switzerland) for granting a 50% discount on all the implant materials used in the presented study. The co‐operation of the staff of the centres involved in the study is highly appreciated: (1) Peking University, School of Stomatology, Beijing PR China (2) Medical University Graz, University Clinic of Dental Medicine & Oral Health, Department of Oral Surgery and Orthodontics, Graz Austria (3) Griffith University, Gold Coast, School of Dentistry and Oral Health, Queensland, Australia (4) The University of Hong Kong, Faculty of Dentistry, Hong Kong SAR PR China (5) University of Iceland, Faculty of Odontology, Reykjavik, Iceland (6) Shanghai Jiao Tong University, Shanghai Ninth People's Hospital, Department of Implant Dentistry, Shanghai PR China (7) National Dental Centre Singapore, Singapore