Histological and radiological evaluation of sintered and non-sintered deproteinized bovine bone substitute materials in sinus augmentation procedures. A prospective, randomized-controlled, clinical multicenter study.

OBJECTIVES: The objective of this study is to histologically and radiologically compare a sintered and a non-sintered bovine bone substitute material in sinus augmentation procedures. MATERIALS AND METHODS: Thirty-three patients were included in the clinically controlled randomized multicentre study resulting in a total of 44 treated sinuses. After lateral approach, sinuses were filled with either a sintered (SBM, Alpha Bio's Graft®) or a non-sintered (NSBM, Bio Oss®) deproteinized bovine bone substitute material. The augmentation sites were radiologically assessed before and immediately after the augmentation procedure as well as prior to implant placement. Bone trephine biopsies for histological analysis were harvested 6 months after augmentation whilst preparing the osteotomies for implant placement. RESULTS: Healing was uneventful in all patients. After 6 months, radiological evaluation of 43 sinuses revealed a residual augmentation height of 94.65 % (±2.74) for SBM and 95.76 % (±2.15) for NSBM. One patient left the study for personal reasons. Histological analysis revealed a percentage of new bone of 29.71 % (±13.67) for SBM and 30.57 % (±16.07) for NSBM. Residual bone substitute material averaged at 40.68 % (±16.32) for SBM compared to 43.43 % (±19.07) for NSBM. All differences between the groups were not statistically significant (p > 0.05, Student's t test). CONCLUSION: Both xenogeneic bone substitute materials showed comparable results regarding new bone formation and radiological height changes in external sinus grafting procedures. CLINICAL RELEVANCE: Both bone substitute materials allow for a predictable new bone formation following sinus augmentation procedures.

Effect of lateral static load on immediately restored implants: histologic and radiographic evaluation in dogs.

OBJECTIVES: The aim of this study was to evaluate the effect of lateral static load in immediately restored implants in the canine mandible. MATERIAL AND METHODS: In 7 mongrel dogs, all premolars and the first molars were extracted bilaterally in the mandible. Two months after the extractions, 6 implants with sandblasted acid-etched surfaces were placed in each animal, 3 on each side. Randomly, two implants per side were immediately restored with an orthodontic expansion device that promoted lateral excessive static load (test group) or load (control) while the third implant of each side, remained submerged (unloaded group). These loaded devices were cleaned daily with chlorhexidine 0.12%, during the 4 months of study, when the animals were sacrificed and biopsies removed for histometric study. Intra-oral periapicals were made using positioners at the beginning and at the end of the study. RESULTS: Five implants from test group were lost in 3 dogs. Radiographically, there was a marginal bone loss of 3.68 ± 0.74 mm for the test group, 1.63 ± 0.2 mm for the control group and 0.45 ± 0.5 mm for the unloaded group. Histometrically, the percentage of bone-to-implant contact (BIC%) was 35.52 ± 7.32%, for the test group, 63.16 ± 5.16% for the control group and 42.33 ± 2.14% for the unloaded group. CONCLUSION: In conclusion, the excessive lateral static load negatively affected the behavior of peri-implant bone around immediate restored implants.

Impact of machined versus structured implant shoulder designs on crestal bone level changes: a randomized, controlled, multicenter study.

PURPOSE: The collar region of an implant is its connection to the oral cavity. A balance between osseointegration on one hand and the absence of plaque accumulation on the other hand is necessary for successful implantation. It is yet to be determined which implant collar design, polished or rough, is best to stabilize the crestal bone level, avoiding peri-implantitis and subsequent risk of implant loss. The aim of this study was to investigate the influence of the architecture of the collar region on marginal bone and soft tissue response. METHODS: This prospective, randomized, clinically controlled multicenter study included 58 patients undergoing dental implant treatment using a pair of dental implants with either machined or rough-surfaced shoulder regions. Patients were clinically and radiologically examined for bone level height and signs of inflammation after 6, 12 and 24 months. RESULTS: No implant was lost within the 2 years of follow-up (100% survival rate). No significant differences on crestal bone loss (machined neck: 0.61 mm ± 0.28 mm, rough neck 0.58 mm ± 0.24 mm) and on soft tissue response (probing depth 3-6 mm with bleeding on probing 7.6% in machined-neck implants and in 8.3% in rough neck implants) were observed between implants with machined and roughened neck after 2 years. CONCLUSIONS: Machined and roughened neck implants achieved equally good results concerning peri-implant bone loss, the rate of peri-implantitis and implant survival rate/hard and soft tissue integration. None of the two collar designs showed a clear advantage in peri-implant reaction. Trial registration German Clinical Trials Register, DKRS00029033. Registered 09 May 2022-Retrospectively registered, http://www.dkrs.de.

Immunohistochemical analysis of inflammatory infiltrate in aggressive and chronic periodontitis: a comparative study.

This immunohistochemical study evaluated the inflammatory infiltrate with its cluster differentiation markers (CD 4, CD 8, CD 20, and CD 68) in aggressive and chronic periodontitis gingival tissues in order to identify the specific cell distribution. Twenty-seven human gingival biopsies were obtained and analyzed. Fourteen patients were suffering from chronic periodontitis and six from aggressive periodontitis; seven patients with healthy gingiva were included as the control group. The specimens were immunohistochemically stained for anti-CD 4 (T helper cells), anti-CD 8 (T cytotoxic/suppressor), anti CD-20 (B plasma cells) and anti CD-68 (macrophages). Chronic periodontitis samples were mainly dominated by CD 4 and CD 8+ cells. On the contrary, in aggressive periodontitis patients all four cell types (CD 4, CD 8, CD 20 and CD 68 + cells, respectively) were remarkably increased. CD 20+ cells were significantly (p < 0.05) more prevalent in aggressive versus chronic periodontitis. The control samples expressed lower CD 4, CD 8, CD 20 and CD 68+ cells confirming a none inflammatory state. The present study demonstrates prevalence for CD 20+ cells in aggressive periodontitis lesions. However, further studies need to be performed to confirm and identify a clear pattern of inflammatory cells and hereafter the mechanisms sustaining the disease.

Influence of titanium implant surface characteristics on bone regeneration in dehiscence-type defects: an experimental study in dogs.

OBJECTIVES: The aim of the present study was to compare bone regeneration in dehiscence-type defects at titanium implants with chemically modified sandblasted/acid-etched (modSLA) or dual acid-etched surfaces with a calcium phosphate nanometre particle modification (DCD/CaP). MATERIALS AND METHODS: Buccal dehiscence-type defects were surgically created following implant site preparation in both the upper and the lower jaws of 12 fox hounds. Both types of implants were randomly allocated in a split-mouth design and left to heal in a submerged position for 2 and 8 weeks. Dissected blocks were processed for histomorphometrical analysis [e.g. new bone height (NBH), percentage of bone-to-implant contact (BIC), area of new bone fill (BF), and area of mineralized tissue (MT) within BF]. RESULTS: At 2 and 8 weeks, both groups revealed comparable mean BF (2.3+/-0.6 to 2.5+/-0.6 mm(2)versus 2.0+/-0.6 to 1.4+/-0.5 mm(2)) and MT (31.1+/-14.3-83.2+/-8.2%versus 38.9+/-15.9-84.4+/-6.3%) values. However, modSLA implants revealed significantly higher mean NBH (2.4+/-0.8 to 3.6+/-0.3 mm versus 0.9+/-0.8 to 1.8+/-1.4 mm) and BIC (53.3+/-11.3-79.5+/-6.6%versus 19.3+/-16.4-47.2+/-30.7%) values than DCD/CaP implants. CONCLUSION: ModSLA implants may have a higher potential to support osseointegration in dehiscence-type defects than DCD/CaP implants.

Influence of frequent clinical probing during the healing phase on healthy peri-implant soft tissue formed at different titanium implant surfaces: a histomorphometrical study in dogs.

OBJECTIVES: To investigate (i) the impact of different titanium implant surfaces on soft tissue integration over 6 months, and (ii) the influence of frequent clinical probing during the healing phase on the established mucosal seal. MATERIAL AND METHODS: Standardized clinical probing was randomly performed (12 dogs, probing versus control) at different transmucosal surfaces [machined (M), sand-blasted/acid-etched (SLA), and chemically modified acid-etched (modA), modSLA] at 2, 4, 8, and 12 weeks (i.e. 1 x , 2 x , 3 x , and 4 x). Histomorphometrical analysis (e.g. mucosal margin (PM) - apical extension of the junctional epithelium (aJE), PM - coronal level of bone-to-implant contact (CBI) was performed at 4, 8, 12, and 24 weeks. RESULTS: While M and SLA groups revealed a split formation, epithelial cells and connective tissue were in close contact to modA and modSLA surfaces. Frequent clinical probing (i.e. 3 x and 4 x) increased mean pocket depths, PM-aJE, and aJE-CBI values in all groups and markedly disrupted the epithelial and connective tissue attachment. CONCLUSIONS: It was concluded that irrespective of the surface characteristics, a frequent clinical probing at short intervals during the healing phase was associated with dimensional and structural changes of the mucosal seal.

Initial pattern of angiogenesis and bone formation following lateral ridge augmentation using rhPDGF and guided bone regeneration: an immunohistochemical study in dogs.

OBJECTIVES: To evaluate (i) the effects of rhPDGF-BB on localized ridge augmentation using a natural bone mineral (NBM), and (ii) the influence of a collagen membrane (CM) on factor activity. MATERIALS AND METHODS: Chronic-type alveolar ridge defects (n = 4 dogs) were randomly allocated in a split-mouth design as follows: upper jaw: NBM + rhPDGF-BB + CM (test) vs. NBM + rhPDGF-BB (control), and lower jaw: NBM + rhPDGF-BB + CM (test) vs. NBM + CM (control). After 3 weeks, dissected blocks were prepared for immunohistochemical (angiogenesis - TG) and histomorphometrical analysis [e.g. augmented area (AA), mineralized - (MT), non-mineralized tissue (NMT) (mm(2))]. RESULTS: Lower jaw: TG and mineralization of AA mainly originated from the defect borders. Test sites revealed a pronounced TG antigen reactivity and higher AA and MT values (mean and median). Upper jaw: control sites revealed a dislocation of AA in caudal direction, but also an improved vascularization in the peripheral wound area. While MT values (median) appeared to be comparable in both groups, AA, NMT, and NBM values (mean and median) tended to be higher at test sites. CONCLUSIONS: It was concluded that (i) rhPDGF-BB soak-loaded on NBM might have the potential to support bone formation at chronic-type lateral ridge defects, and (ii) the application of CM did not seem to interfere with the factor activity, but ensured a stabilization of the graft particles.

Lateral ridge augmentation using equine- and bovine-derived cancellous bone blocks: a feasibility study in dogs.

OBJECTIVES: The aim of the present study was to histologically evaluate and compare a new prototype collagen type I/III-containing equine- (EB) and a bovine- (BB) derived cancellous bone block in a dog model. MATERIALS AND METHODS: Four standardized box-shaped defects were bilaterally created at the buccal aspect of the alveolar ridge in the lower jaws of five beagle dogs and randomly allocated to either EB or BB. Each experimental site was covered by a native (non-crosslinked) collagen membrane and left to heal in a submerged position for 12 weeks. Dissected blocks were processed for semi-/and quantitative analyses. RESULTS: Both groups had no adverse clinical or histopathological events (i.e. inflammatory/foreign body reactions). BB specimens revealed no signs of biodegradation and were commonly embedded in a fibrous connective tissue. New bone formation and bony graft integration were minimal. In contrast, EB specimens were characterized by a significantly increased cell (i.e. osteoclasts and multinucleated giant cells)-mediated degradation of the graft material (P<0.001). The amount and extent of bone ingrowth was consistently higher in all EB specimens, but failed to reach statistical significance in comparison with the BB group (P>0.05). CONCLUSIONS: It was concluded that the application of EB may not be associated with an improved bone formation than BB.

Stability of crestal bone level at platform-switched non-submerged titanium implants: a histomorphometrical study in dogs.

OBJECTIVES: To investigate the influence of platform switching on crestal bone level changes at non-submerged titanium implants over a period of 6 months. MATERIAL AND METHODS: Titanium implants (n=72) were placed at 0.4 mm above the alveolar crest in the lower jaws of 12 dogs and randomly assigned to either matching or non-matching (circumferential horizontal mismatch of 0.3 mm) healing abutments. At 4, 8, 12, and 24 weeks, dissected blocks were processed for histomorphometrical analysis. Measurements were made between the implant shoulder (IS) and the apical extension of the long junctional epithelium (aJE), the most coronal level of bone in contact with the implant (CLB), and the level of the alveolar bone crest (BC). RESULTS: At 24 weeks, differences in the mean IS-aJE, IS-CLB, and IS-BC values were 0.2 +/- 1.2, 0.3 +/- 0.7, and 0.3 +/- 0.8 mm at the buccal aspect, and 0.2 +/- 0.9, 0.3 +/- 0.5, and 0.3 +/- 0.8 mm at the lingual aspect, respectively. Comparisons between groups revealed no significant differences at either the buccal or the lingual aspects. CONCLUSIONS: It was concluded that (i) bone remodelling was minimal in both groups and (ii) platform switching may not be of crucial importance for maintenance of the crestal bone level.

Influence of recombinant human platelet-derived growth factor on lateral ridge augmentation using biphasic calcium phosphate and guided bone regeneration: a histomorphometric study in dogs.

BACKGROUND: The present study investigated the effects of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) on initial bone formation following lateral ridge augmentation using biphasic calcium phosphate (BCP) in combination with a native collagen membrane (CM) in dogs. METHODS: Eight chronic-type mandibular lateral ridge defects in four beagle dogs (two defects each) were randomly allocated in a split-mouth design to BCP + rhPDGF-BB + CM (test) or BCP + CM (control). After 3 weeks, dissected blocks were prepared for immunohistochemical (angiogenesis-transglutaminase II [TG]) and histomorphometric analysis (e.g., augmented area [AA] and mineralized tissue [MT]). The biologic activity of rhPDGF-BB soak-loaded BCP was verified by means of alkaline phosphatase and lactate dehydrogenase assays in a SaOs-2-osteoblast-like cell culture. RESULTS: Both groups exhibited a comparable pattern of blood vessel and bone formation that mainly originated from the adjacent alveolar bone. However, test sites revealed a pronounced TG antigen reactivity, which was associated with statistically significant higher mean AA (8.5 +/- 0.9 mm(2) versus 7.1 +/- 1.1 mm(2)) and MT (2.7 +/- 0.9 mm(2) versus 1.7 +/- 0.8 mm(2)) values compared to the control sites (P <0.05; paired t test). CONCLUSION: BCP + rhPDGF-BB might have the potential to support the initial stages of guided bone regeneration at chronic-type lateral ridge defects.

Guided bone regeneration using rhGDF-5- and rhBMP-2-coated natural bone mineral in rat calvarial defects.

OBJECTIVES: The aim of the present study was to assess the influence of either recombinant human growth and differentiation factor 5 (rhGDF-5)- or recombinant human bone morphogenetic protein 2 (rhBMP-2)-coated natural bone mineral (NBM) on guided bone regeneration in a rat calvarial defect model. MATERIAL AND METHODS: Two monocortical critical-size calvarial defects (diameter 6 mm, depth 1.5 mm) were prepared in a total of 90 rats each (n=180 defects) and randomly allocated to the following groups: (1) NBM+collagen membrane (BG), (2) rhBMP-2+NBM+BG, (3) rhGDF-5+NBM+BG, (4) autogenous bone (AB)+BG, or (5) untreated control (C). At 1, 2, 4, 8, 16, and 24 weeks, dissected blocks were processed for histological [e.g. area (mm(2)) of mineralized tissue (MT)] and immunohistochemical (osteocalcin - OC, angiogenesis - TG) analysis. RESULTS: At 2 weeks, both coated NBM groups exhibited the formation of a thin hard tissue bridge underneath the BG. All test groups revealed significantly higher mean MT values than the C group at 24 weeks. rhBMP-2+NBM+BG-treated defects revealed significantly higher mean MT values in comparison with the AB+BG (8 and 24 weeks), NBM+BG (2 and 4 weeks), and rhGDF-5+NBM+BG (2, 16, and 24 weeks) groups, respectively. Immunoreactions to either OC or TG were comparable in all test groups. CONCLUSION: It was concluded that (i) all treatment procedures investigated supported bone regeneration at 24 weeks and (ii) rhBMP-2 might have the potential to improve the outcome of healing, particularly during the early stages of healing.

Biodegradation of different synthetic hydrogels made of polyethylene glycol hydrogel/RGD-peptide modifications: an immunohistochemical study in rats.

AIM: The aim of the present study was to investigate the pattern of biodegradation of different polyethylene glycol (PEG) hydrogel/RGD-peptide modifications in rats. MATERIAL AND METHODS: Two different hydrogels were employed: (i) a combination of four-arm PEG-thiol, M(n)=2.3 kDa, and eight-arm PEG-acrylate, M(n)=2.3 kDa (PEG1); and (ii) a combination of four-arm PEG-thiol, M(n)=2.3 kDa, and four-arm PEG-acrylate, M(n)=15 kDa (PEG2). Both PEG1 and PEG2 were either used alone or combined with a nine amino acid cys-RGD peptide (RGD). A non-cross-linked porcine type I and III collagen membrane [BioGide (BG)] served as control. Specimens were randomly allocated in unconnected subcutaneous pouches separated surgically on the back of 60 wistar rats, which were divided into six groups (1, 2, 4, 8, 16, and 24 weeks). Specimens were prepared for histological (tissue integration, foreign body reactions, biodegradation) and immunohistochemical (angiogenesis) analysis. RESULTS: All materials investigated revealed unimpeded and comparable tissue integration without any signs of foreign body reactions. While BG exhibited transmembraneous blood vessel formation at 1 week, all PEG specimens were just surrounded by a well-vascularized connective tissue. The hydrolytic disruption of PEG1 and PEG1/RGD specimens was associated with an ingrowth of blood vessels at 4 weeks. Biodegradation times were highest for PEG1 (24 weeks)>PEG1/RGD (16 weeks)>BG (4 weeks)>PEG2=PEG2/RGD (2 weeks). CONCLUSION: Within the limits of the present study, it was concluded that (i) all materials investigated revealed a high biocompatibility and tissue integration, and (ii) hydrogel biodegradation was dependent on PEG composition.

Evaluation of the effect of tumor necrosis factor-alpha gene polymorphism on the risk of peri-implantitis: a case-control study.

PURPOSE: Tumor necrosis factor-alpha (TNFalpha) is a proinflammatory cytokine, which promotes bone resorption and mediates the inflammatory response to infection. Because implant failures appear to cluster in subsets of individuals, this phenomenon may be related to gene polymorphisms. Therefore, the aim of this study was to investigate the relationship between a specific polymorphism in the TNFalpha gene (allele 2 of TNFalpha(-308)) and peri-implantitis. MATERIALS AND METHODS: This case-control study included Caucasian nonsmoking Brazilian patients with implant-supported restorations. Oral epithelial cells were taken from patients with and without peri-implantitis to evaluate the frequencies of different alleles of the TNFalpha(-308) gene by polymerase chain reaction. RESULTS: Ninety patients (49 with peri-implantitis and 41 with healthy implants) were enrolled in this study. Polymorphism in allele 2 of TNFalpha(-308) was not associated with an increased risk for peri-implantitis (P = .8171), although 14.63% of the subjects in the control group carried allele 2 and 19.39% in the peri-implantitis group carried allele 2 (chi-squared = 0.708; P = .5202). CONCLUSION: Polymorphism of the TNFalpha(-308) gene was not associated with an increased risk of peri-implantitis in the population evaluated in this study.

Vertical ridge augmentation using xenogenous bone blocks: a histomorphometric study in dogs.

PURPOSE: Because vertical ridge augmentation with autogenous bone blocks carries with it a risk of graft resorption and donor site morbidity, the aim of the present study was to compare histologically the healing following vertical ridge augmentation using screwable, xenogenous deproteinized blocks or autologous bone blocks in dogs. MATERIALS AND METHODS: Standardized vertical mandibular defects were surgically created in edentulous ridges of six foxhounds. Two bone blocks (6 x 10 x 15 mm) were inserted on each mandibular side and fixed with both a titanium implant and an osteosynthetic screw. Three different therapies were tested: (1) xenogenous block alone; (2) xenogenous block, covered with a chemically cross-linked collagen membrane; and (3) autologous blocks, harvested during defect preparation. After 3 months of submerged healing, the miniscrews were removed and replaced by dental implants. Following an additional healing period of 3 months, the animals were sacrificed, and dissected blocks were prepared for histomorphometric analysis. RESULTS: During the primary healing period, three of 12 hemimandibles (six blocks) had to be removed because of severe inflammatory reactions (two xenogenous block sites with collagen membrane, one autologous block site). In general, histologic analysis revealed that xenogenous blocks, used alone or combined with a collagen membrane, exhibited osteoconductive properties on a level equivalent to that of autologous blocks, resulting in means of 50% to 60% of ossification of the blocks. Some parts of the xenograft were encased in soft tissue, partly surrounded by multinuclear giant cells. However, all groups showed obvious signs of bone/graft resorption. CONCLUSIONS: Within the limits of the present study, it was concluded that the examined screwable xenogenous bone block might be a useful scaffold for ridge augmentation procedures. However, the combination of xenogenous blocks with a cross-linked collagen membrane did not appear to improve outcomes.

Microbiological and clinical effects of adjunctive systemic metronidazole and amoxicillin in the non-surgical treatment of peri-implantitis: 1 year follow-up.

The aim of this study was to evaluate the effects of adjunct systemic antibiotic treatment with metronidazole (MTZ) and amoxicillin (AMX) in patients receiving non-surgical subgingival debridement (NSD) for peri-implantitis. Forty subjects presenting with at least one implant with severe peri-implantitis were randomized into an experimental group [treated with NSD plus MTZ (400 mg) and AMX (500 mg) three times a day for 14 days] and a control group treated with NSD plus placebo. Clinical parameters and submucosal biofilm profiles were evaluated up to 1 year post-treatment. Overall, both treatments improved clinical parameters over time. At 1 year, mean probing depth (PD), mean clinical attachment (CA) level and proportions of red complex pathogens did not differ significantly between the two groups. In addition, mean PD and CA changes to 1-year posttreatment did not differ significantly between the two groups between baseline and 1-year post-treatment. These results suggest that the addition of MTZ and AMX to the treatment protocol of patients undergoing NSD for with severe peri-implantitis does not improve the clinical and microbiological outcomes of NSD. The fact that half of the implants in both groups did not achieve clinical success (PD < 5 mm, no BoP, no bone loss) suggest that neither of the tested protocols were effective for treating severe peri-implantitis.

Bone regeneration in dehiscence-type defects at non-submerged and submerged chemically modified (SLActive) and conventional SLA titanium implants: an immunohistochemical study in dogs.

OBJECTIVES: The aim of the present study was to evaluate bone regeneration in dehiscence-type defects at non-submerged and submerged titanium implants with chemically modified (mod) and conventional sandblasted/acid-etched (SLA) surfaces. MATERIAL AND METHODS: Standardized buccal dehiscence defects were surgically created following implant site preparation in both the upper and lower jaws of 12 beagle dogs. Both types of implants were randomly assigned to either a non-submerged or a submerged healing procedure. After 1, 2, 4, and 8 weeks, dissected blocks were processed for histomorphometrical [e.g. new bone height (NBH), per cent linear fill (PLF), percentage of bone to implant contact (BIC-D), area of new bone fill (BF)] and immunohistochemical analysis. RESULTS: At 8 weeks, non-submerged and submerged SLA implants revealed significantly lower mean NBH (1.1+/-0.8-1.9+/-1.2 mm), PLF (27.7+/-20.3-46.0+/-28.5%), BIC-D (26.8+/-10.4-46.2+/-16.2%), and BF (1.3+/-0.9-3.4+/-2.8 mm(2)) values than respective modSLA implants [NBH (2.6+/-0.8-4.3+/-0.1 mm), PLF (64.2+/-19.4-107.2+/-4.7%), BIC-D (67.5+/-18.8-82.1+/-14.8%), BF (2.9+/-1.0-6.7+/-1.1 mm(2))]. Within modSLA groups, significantly highest BF values were observed at submerged implants. CONCLUSION: It was concluded that (i) modSLA titanium surfaces promoted bone regeneration in acute-type buccal dehiscence defects and (ii) a submerged healing procedure improved the outcome of healing additionally.

Two-year clinical results following treatment of peri-implantitis lesions using a nanocrystalline hydroxyapatite or a natural bone mineral in combination with a collagen membrane.

OBJECTIVES: The aim of the present case series was to evaluate the 2-year results obtained following treatment of peri-implantitis lesions using either a nanocrystalline hydroxyapatite (NHA) or a natural bone mineral in combination with a collagen membrane (NBM+CM). MATERIAL AND METHODS: Twenty-two patients suffering from moderate peri-implantitis (n=22 intra-bony defects) were randomly treated with (i) access flap surgery (AFS) and the application of NHA, or with AFS and the application of NBM+CM. Clinical parameters were recorded at baseline and after 12, 18, and 24 months of non-submerged healing. RESULTS: Two patients from the NHA group were excluded from the study due to severe pus formation at 12 months. At 24 months, both groups revealed clinically important probing depth (PD) reductions (NHA: 1.5+/-0.6 mm; NBM+CM: 2.4+/-0.8 mm) and clinical attachment level (CAL) gains (NHA: 1.0+/-0.4 mm; NBM+CM: 2.0+/-0.8 mm). However, these clinical improvements seemed to be better in the NBM+CM group (difference between groups: PD reduction: 0.9+/-0.2 mm; CAL gain: 1.0+/-0.3 mm). CONCLUSION: Both treatment procedures have shown efficacy over a period of 24 months, however, the application of NBM+CM may result in an improved outcome of healing.

Lateral ridge augmentation using particulated or block bone substitutes biocoated with rhGDF-5 and rhBMP-2: an immunohistochemical study in dogs.

OBJECTIVES: The aim of the present study was to immunohistochemically evaluate lateral ridge augmentation using a particulated (BOG) or block (BOB) natural bone mineral biocoated with rhGDF-5 and rhBMP-2 in dogs. MATERIALS AND METHODS: Three standardized box-shaped defects were surgically created at the buccal aspect of the alveolar ridge in each quadrant of eight beagle dogs. After 2 months of healing, the chronic-type defects were randomly allocated in a split-mouth design to either (i) BOG or (ii) BOB biocoated with (a) rhGDF-5 or (b) rhBMP-2, respectively. Uncoated grafts served as controls. After 3 and 8 weeks, dissected blocks were prepared for immunohistochemical [osteocalcin (OC)] and histomorphometrical analysis [e.g. area (mm(2)) of new bone fill (BF), newly formed mineralized (MT) and non-mineralized tissue (NMT)]. RESULTS: rhBMP-2 biocoated BOG revealed significantly highest BF and MT values at 3 (upper and lower jaws - UJ/LJ - compared with BOG) and 8 weeks (UJ - compared with rhGDF-5). Biocoating of BOB using both rhGDF-5 and rhBMP-2 resulted in significantly increased MT values at 8 weeks (UJ/LJ - compared with BOB). In all groups, NMT adjacent to BOG and BOB scaffolds revealed pronounced signs of an OC antigen reactivity. CONCLUSIONS: Within the limits of the present study, it was concluded that both rhGDF-5 and rhBMP-2 have shown efficacy; however, their bone regenerative effect was markedly influenced by the carrier.

Immunohistochemical characterization of guided bone regeneration at a dehiscence-type defect using different barrier membranes: an experimental study in dogs.

OBJECTIVES: The aim of the present study was to evaluate immunohistochemically the pattern of guided bone regeneration (GBR) using different types of barrier membranes. MATERIAL AND METHODS: Standardized buccal dehiscence defects were surgically created following implant bed preparation in 12 beagle dogs. Defects were randomly assigned to six different GBR procedures: a collagen-coated bone grafting material (BOC) in combination with either a native, three cross-linked, a titanium-reinforced collagen membrane, or expanded polytetrafluorethylene (ePTFE), or BOC alone. After 1, 2, 4, 6, 9, and 12 weeks of submerged healing, dissected blocks were processed for immunohistochemical (osteocalcin - OC, transglutaminase II - angiogenesis) and histomorphometrical analysis [e.g., bone-to-implant contact (BIC), area of new bone fill (BF)]. RESULTS: In general, angiogenesis, OC antigen reactivity, and new bone formation mainly arose from open bone marrow spaces at the bottom of the defect and invaded the dehiscence areas along the implant surface and BOC. At 4 weeks, membranes supporting an early transmembraneous angiogenesis also exhibited some localized peripheral areas of new bone formation. However, significantly increasing BIC and BF values over time were observed in all groups. Membrane exposure after 10-12 weeks was associated with a loss of the supporting alveolar bone in the ePTFE group. CONCLUSION: Within the limits of the present study, it was concluded that (i) angiogenesis plays a crucial role in GBR and (ii) all membranes investigated supported bone regeneration on an equivalent level.

Composition of supra- and subgingival biofilm of subjects with healthy and diseased implants.

OBJECTIVES: The purpose of this study was to compare the microbial composition of supra- and subgingival biofilm in subjects with and without peri-implantitis. MATERIAL AND METHODS: Forty-four subjects (mean age 48.9 +/- 13.51 years) with at least one implant restored and functional for at least 2 years were assigned to two groups: a peri-implantitis group (n=22), consisting of subjects presenting peri-implant sites with radiographic defects >3 mm, bleeding on probing and/or suppuration; and a control group (n=22), consisting of subjects with healthy implants. The clinical parameters evaluated were plaque index, gingival bleeding, bleeding on probing, suppuration, probing depth and clinical attachment level. Supra- and subgingival biofilm samples were taken from the deepest sites of each implant and analyzed for the presence of 36 microorganisms by checkerboard DNA-DNA hybridization. RESULTS: Higher mean counts of Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia were observed in the peri-implantitis group, both supra- and subgingivally (P<0.05). The proportions of the pathogens from the red complex were elevated, while host-compatible beneficial microbial complexes were reduced in diseased compared with healthy implants. The microbiological profiles of supra- and subgingival environments did not differ substantially within each group. CONCLUSION: Marked differences were observed in the composition of supra- and subgingival biofilm between healthy and diseased implants. The microbiota associated with peri-implantitis was comprised of more periodontal pathogenic bacterial species, including the supragingival biofilm.