In ovariectomy-induced osteoporotic rat models, BMP-2 substantially reversed an impaired alveolar bone regeneration whereas PDGF-BB failed.

OBJECTIVES: We previously suggested an ovariectomy (OVX)-induced osteoporotic rat model showing an impaired alveolar bone defect healing. This study aimed to evaluate and compare the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) and recombinant human platelet-derived growth factor-BB (rhPDGF-BB) on alveolar bone defect healing in OVX-induced osteoporotic rats. MATERIALS AND METHODS: A total of forty-one female rats were divided into four groups: a collagen group (n=10), a PDGF-BB group (n=11), a BMP-2 group (n=10), and a control group (n=10). Four months after OVX, alveolar bone drill-hole defects were created and grafted with collagen gel, rhPDGF-BB/collagen gel, or rhBMP-2/collagen gel. The defects in the control group were not grafted with any material. Defect healing was evaluated by histological, histomorphometric, and microcomputed tomographic (micro-CT) analyses at 2 and 4 weeks. RESULTS: According to the micro-CT analysis, the BMP-2 group exhibited the greatest bone volume fraction among all groups, while the PDGF-BB group did not show significant differences compared with the collagen group. The histomorphometric analysis showed a significantly larger amount of new bone area in the BMP-2 group than in the control and collagen groups at 4 weeks; however, the PDGF-BB group did not reach significant superiority compared with the other groups. CONCLUSIONS: Alveolar bone regeneration was significantly enhanced by the local use of rhBMP-2/collagen gel compared with the use of rhPDGF-BB/collagen gel in OVX-induced osteoporotic rats. CLINICAL RELEVANCE: A treatment modality using rhBMP-2 may be a promising approach to promote alveolar bone regeneration in patients suffering from postmenopausal osteoporosis.

Bone reconstruction after surgical treatment of experimental peri-implantitis defects at a sandblasted/acid-etched hydroxyapatite-coated implant: an experimental study in the dog.

OBJECTIVES: The objective of this study was to evaluate bone formation/osseointegration following surgical treatment of experimental peri-implantitis at dental implants with different surface characteristics exposed to ligature-induced breakdown conditions. METHODS: Ten turned (control), 10 sandblasted/acid-etched (SA), and 10 SA/hydroxyapatite nanocoated (HA) implants were installed into the edentulated posterior mandible in five Beagle dogs and allowed to osseointegrate for 12 weeks. Ligature-induced breakdown defects were then induced over 23 weeks using stainless steel wire ligatures. The ligatures were removed and soft tissues were allowed to heal for 3 weeks. Next, exposed implant surfaces were decontaminated followed by guided bone regeneration using a collagen membrane and submerged wound healing. The animals were euthanized for histometric analysis at 12 weeks post-surgery. RESULTS: The radiographic analysis showed vertical bone loss following ligature-induced breakdown without statistically significant differences among implant technologies. The histometric analysis showed significantly enhanced bone formation (height) at SA and SA/HA compared with turned implants (p = 0.028) following reconstructive surgery. Bone formation area was greater at SA/HA compared with turned implants, however the difference did not reach statistical significance. CONCLUSIONS: While ligature-induced defect progression does not appear implant surface dependent in this animal model, bone formation at the decontaminated implant surfaces appears more favourable at SA and SA/HA over turned implants following reconstructive surgery.

The cumulative survival rate of dental implants with micro-threads: a long-term retrospective study.

PURPOSE: This study aimed to evaluate the long-term cumulative survival rate (CSR) of dental implants with micro-threads in the neck over a 10-year follow-up period and to examine the factors influencing the survival rate of dental implants. METHODS: This retrospective study was based on radiographic and dental records. In total, 151 patients received 490 Oneplant® dental implants with an implant neck micro-thread design during 2006-2010 in the Department of Periodontology of Seoul National University Dental Hospital. Implant survival was evaluated using Kaplan-Meier analysis. Cox proportional hazard regression analysis was used to identify the factors influencing implant failure. RESULTS: Ten out of 490 implants (2.04%) failed due to fixture fracture. The CSR of the implants was 97.9%, and no significant difference was observed in the CSR between external- and internal-implant types (98.2% and 97.6%, respectively, P=0.670). In Cox regression analysis, 2-stage surgery significantly increased the risk of implant failure (hazard ratio: 4.769, P=0.039). There were no significant differences in influencing factors, including sex, age, implant diameter, length, fixture type, location, surgical procedure, bone grafting, and restoration type. CONCLUSIONS: Within the limitations of this retrospective study, the micro-thread design of the implant neck was found to be favorable for implant survival, with stable clinical outcomes.

The healing pattern of a 4 mm proximal infrabony defect was not significantly different from a 2 mm defect adjacent to dental implant in a canine mandible.

PURPOSE: The purpose of this study was to evaluate and compare the healing patterns of 2-mm and 4-mm proximal infrabony defects adjacent to dental implants in canine mandibles. METHODS: Four male beagles were used. Two groups were created: a 2-mm group (n=4) and a 4-mm group (n=4) depending on the horizontal dimension of proximal infrabony defects adjacent to implants. Bone healing patterns between the 2 groups were evaluated and compared at 8 and 16 weeks using radiographic, histological, histomorphometric, and fluorescent labelling analyses. RESULTS: According to microcomputed tomography, the median bone volume fraction, bone mineral density, and the percentage of radiographic distance from the defect bottom to the most coronal bone-to-implant contact (radio-mcBIC) were 32.9%, 0.6 g/cm3, and 73.7% (8 weeks) and 45.7%, 0.7 g/cm3, and 76.0% (16 weeks) in the 2-mm group and 57.7%, 0.8 g/cm3, and 75.7% (8 weeks) and 50.9%, 0.8 g/cm3, and 74.7% (16 weeks) in the 4-mm group, respectively. According to histomorphometry, the median bone area fraction, mcBIC and the percentage of BIC amounted to 36.7%, 3.4 mm, and 58.4% (8 weeks) and 49.2%, 3.4 mm, and 70.2% (16 weeks) in the 2-mm group and 50.0%, 3.0 mm, and 64.8% (8 weeks) and 55.7%, 3.0 mm, and 69.6% (16 weeks) in the 4-mm group, respectively. No statistically significant differences were found between the groups for any variables (P>0.05). CONCLUSIONS: The proximal defects that measured 2 mm and 4 mm showed similar healing patterns at 8 and 16 weeks, and the top of bone formation in the defects was substantially limited to a maximum of 1.6 mm below the implant shoulder in both groups.

Modified tunneling technique for root coverage of anterior mandible using minimal soft tissue harvesting and volume-stable collagen matrix: a retrospective study.

PURPOSE: In this study, we aimed to evaluate the clinical validity of the modified tunneling technique using minimal soft tissue harvesting and volume-stable collagen matrix in the anterior mandible. METHODS: In total, 27 anterior mandibular teeth and palatal donor sites in 17 patients with ≥1 mm of gingival recession (GR) were analyzed before and after root coverage. For the recipient sites, vertical vestibular incisions were made in the interdental area and a subperiosteal tunnel was created with an elevator. After both sides of the marginal gingiva were tied to one another, a prepared connective tissue graft and volume-stable collagen matrix were inserted through the vestibular vertical incision and were fixed with resorbable suture material. The root coverage results of the recipient site were measured at baseline (T0), 3 weeks (T3), 12 weeks (T12), and the latest visit (Tl). For palatal donor sites, a free gingival graft from a pre-decided area avoiding the main trunk of the greater palatine artery was harvested using a prefabricated surgical template at a depth of 2 mm after de-epithelization using a rotating bur. In each patient, the clinical and volumetric changes at the donor sites between T0 and T3 were measured. RESULTS: During an average follow-up of 14.5 months, teeth with denuded root lengths of 1-3 mm (n=12), 3-6 mm (n=11), and >6 mm (n=2) achieved root coverage of 97.01%±7.65%, 86.70%±5.66%, and 82.53%±1.39%, respectively. Miller classification I (n=12), II (n=10), and III (n=3) teeth showed mean coverage rates of 97.01%±7.65%, 86.91%±5.90%, and 83.19%±1.62%, respectively. At the donor sites, an average defect depth of 1.41 mm (70.5%) recovered in 3 weeks, and the wounds were epithelized completely in all cases. CONCLUSIONS: The modified tunneling technique in this study is a promising treatment modality for overcoming GR in the anterior mandible.

Effects of hyaluronic acid and deproteinized bovine bone mineral with 10% collagen for ridge preservation in compromised extraction sockets.

BACKGROUND: The aim of this study was to evaluate the efficacy of deproteinized bovine bone mineral with 10% collagen (DBBM-C) soaked with hyaluronic acid (HA) for ridge preservation in compromised extraction sockets. METHODS: Bilateral third, fourth premolars and first molar were hemisected, distal roots were extracted, and then combined endodontic periodontal lesion was induced in the remaining mesial roots. After 4 months, the mesial roots were extracted and the following four treatments were randomly performed: Absorbable collagen sponge (ACS), ACS soaked with HA (ACS+HA), ridge preservation with DBBM-C covered with a collagen membrane (RP), ridge preservation with DBBM-C mixed with HA and covered with a collagen membrane (RP+HA). Animals were sacrificed at 1 and 3 months following treatment. Ridge dimensional changes and bone formation were examined using microcomputed tomography, histology, and histomorphometry. RESULTS: At 1 month, ridge width was significantly higher in the RP and RP+HA groups than in the ACS and ACS+HA groups, while the highest proportion of mineralized bone was observed in ACS+HA group. At 3 months, ridge width remained significantly higher in the RP and RP+HA groups than in the ACS and ACS+HA groups. ACS+HA and RP+HA treatments featured the highest proportion of mineralized bone and bone volume density compared with the other groups. No statistical difference was observed between ACS+HA and RP+HA treatments. CONCLUSIONS: Ridge preservation with the mixture DBBM-C/HA prevented dimensional shrinkage and improved bone formation in compromised extraction sockets at 1 and 3 months.

The impact of surface treatment in 3-dimensional printed implants for early osseointegration: a comparison study of three different surfaces.

3D printing technology has been gradually applied to various areas. In the present study, 3D-printed implants were fabricated with direct metal laser sintering technique for a dental single root with titanium. The 3D implants were allocated into following groups: not treated (3D-None), sandblasted with a large grit and acid-etched (3D-SLA), and target-ion-induced plasma-sputtered surface (3D-TIPS). Two holes were drilled in each tibia of rabbit, and the three groups of implants were randomly placed with a mallet. Rabbits were sacrificed at two, four, and twelve weeks after the surgery. Histologic and histomorphometric analyses were performed for the evaluation of mineralized bone-to-implant contact (mBIC), osteoid-to-implant contact (OIC), total bone-to-implant contact (tBIC), mineralized bone area fraction occupancy (mBAFO), osteoid area fraction occupancy (OAFO), and total bone area fraction occupancy (tBAFO) in the inner and outer areas of lattice structure. At two weeks, 3D-TIPS showed significantly higher inner and outer tBIC and inner tBAFO compared with other groups. At four weeks, 3D-TIPS showed significantly higher outer OIC than 3D-SLA, but there were no significant differences in other variables. At twelve weeks, there were no significant differences. The surface treatment with TIPS in 3D-printed implants could enhance the osseointegration process in the rabbit tibia model, meaning that earlier osseointegration could be achieved.

Ex vivo bone morphogenetic protein-2 gene delivery using gingival fibroblasts promotes bone regeneration in rats.

AIM: The aim of the present study was to investigate bone regeneration following ex vivo bone morphogenetic protein-2 (BMP-2) gene delivery using human gingival fibroblasts (HGFs) in rat calvarial defects. MATERIALS AND METHODS: An 8 mm craniotomy defect was created in Sprague-Dawley rats. The animals were divided into four groups: (1) non-grafted group, the defect was left empty; (2) collagen matrix group, the defect was filled with collagen matrix only; (3) HGF group, the defect was filled with non-transduced HGFs on collagen matrix; (4) BMP-2/HGF group, the defect was filled with BMP-2 gene-transduced HGFs on collagen matrix. Animals were sacrificed at 2 and 4 weeks after surgery, and micro-computed tomographic and histologic observations were performed. RESULTS: The BMP-2/HGF group showed promoted osseous healing of calvarial defects, as compared with the other groups. At both 2 and 4 weeks, regenerated bone area was significantly greater in the BMP-2/HGF group than the other three groups. Quite a few number of transplanted HGFs were observed within the regenerated bone tissues. CONCLUSIONS: The results of this study suggest that ex vivo BMP-2 gene delivery induces prominent bone regeneration in vivo and HGFs may be useful as target cells for ex vivo gene therapy.

Efficacy of salivary versus subgingival bacterial sampling for the detection and quantification of periodontal pathogens.

PURPOSE: The aim of this study was to investigate the efficacy and validity of subgingival bacterial sampling using a retraction cord, and to evaluate how well this sampling method reflected changes in periodontal conditions after periodontal therapy. METHODS: Based on clinical examinations, 87 subjects were divided into a healthy group (n=40) and a periodontitis group (n=47). Clinical measurements were obtained from all subjects including periodontal probing depth (PD), bleeding on probing (BOP), clinical attachment loss (CAL), and the plaque index. Saliva and gingival crevicular fluid (GCF) as a subgingival bacterial sample were sampled before and 3 months after periodontal therapy. The salivary and subgingival bacterial samples were analyzed by reverse-transcription polymerase chain reaction to quantify the following 11 periodontal pathogens: Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythus (Tf), Treponema denticola (Td), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn), Pavimonas micra (Pm), Campylobacter rectus (Cr), Prevotella nigrescens (Pn), Eikenella corrodens (Ec), and Eubacterium nodatum (En). RESULTS: Non-surgical periodontal therapy resulted in significant decreases in PD (P<0.01), CAL (P<0.01), and BOP (P<0.05) after 3 months. Four species (Pg, Tf, Pi, and Pm) were significantly more abundant in both types of samples in the periodontitis group than in the healthy group. After periodontal therapy, Cr was the only bacterium that showed a statistically significant decrease in saliva, whereas statistically significant decreases in Cr, Pg, and Pn were found in GCF. CONCLUSIONS: Salivary and subgingival bacterial sampling with a gingival retraction cord were found to be equivalent in terms of their accuracy for differentiating periodontitis, but GCF reflected changes in bacterial abundance after periodontal therapy more sensitively than saliva.

Comparison of Periodontopathic Bacterial Profiles of Different Periodontal Disease Severity Using Multiplex Real-Time Polymerase Chain Reaction.

Periodontopathic bacteria are known to have a pivotal role in the pathogenesis of periodontitis. The aim of the study was to quantitatively compare bacterial profile of patients with different severity of periodontal disease using samples from mouthwash and the subgingival area. Further analysis was performed to evaluate the correlation between mouthwash and two subgingival sampling methods: paperpoint and gingival retraction cord; 114 subjects enrolled in the study, and were divided equally into three groups according to disease severity. Mouthwash and subgingival sampling were conducted, and the samples were quantitatively analyzed for 11 target periodontopathic bacteria using multiplex real-time PCR. There were statistically significant differences in bacterial counts and prevalence of several species between the study groups. Mouthwash sampling showed significant correlations with two different subgingival sampling methods in regard to the detection of several bacteria (e.g., ρ = 0.793 for Porphyromonas gingivalis in severe periodontitis), implying that mouthwash sampling can reflect subgingival microbiota. However, the correlation was more prominent as disease severity increased. Although bacteria in mouthwash have potential to become a biomarker, it may be more suitable for the diagnosis of severe periodontitis, rather than early diagnosis. Further research is required for the discovery of biomarkers for early diagnosis of periodontitis.

Ovariectomy and timing of impaired maxillary alveolar bone regeneration: An experimental study in rats.

BACKGROUND: The aim of this study was to seek the critical time for impairment of alveolar bone regeneration after ovariectomy (OVX) in rats. METHODS: A total of 32 female rats were used. Test group rats were divided into a 2M group (n = 8), a 3M group (n = 8) and a 4M group (n = 8) according to the duration from OVX to defect creation. Bilateral OVX was performed in all test groups, and a sham operation was performed in the control group (n = 8). Drill-hole defects (1.5 mm diameter, 2 mm length) were created on both sides of the maxilla. All rats were euthanized 2 and 4 weeks after the surgery. Microcomputed tomographic (micro-CT), histological, and histomorphometric analyses and in vitro experiments were performed. RESULTS: The 4M group showed significantly less new bone formation and a lower bone mineral density than the other groups in the micro-CT analysis. The histomorphometric analysis also revealed that the 4M group showed significantly less new bone formation than the control and 2M groups. The rats in the 4M group showed significantly higher alkaline phosphatase expression levels and a larger number of calcified nodules than rats in the other groups, whereas osteoclastic activity was significantly lower in the 4M group than in the other groups. CONCLUSIONS: The critical time for impairment of alveolar bone regeneration was 4 months after OVX in rats.

Leukocyte- and platelet-rich fibrin is an effective membrane for lateral ridge augmentation: An in vivo study using a canine model with surgically created defects.

BACKGROUND: Leukocyte- and platelet-rich fibrin (L-PRF) has been suggested to enhance bone healing and the effects of L-PRF need to be evaluated in lateral residual alveolar bone augmentation. This in vivo study aimed to analyze the effects of L-PRF as a membrane on bone regeneration in lateral residual alveolar augmentation. METHODS: Eight mongrel dogs were used; the mandibular premolars were extracted and then three lateral ridge defects were surgically created on each side of the arch. After 4 weeks, guided bone ridge augmentation was performed in each defect with the following treatment groups: N+D (nonresorbable membrane with deproteinized bovine bone mineral [DBBM]), N+B (nonresorbable membrane with ß-tricalcium phosphate [ß-TCP]), R+D (resorbable membrane with DBBM), R+B (resorbable membrane with ß-TCP), and P+D (L-PRF with DBBM), and P+B (L-PRF and ß-TCP). Following 4 weeks of bone healing, the new bone amount for each group was measured by light microscopy (primary outcome) and microcomputed tomography (micro-CT) (secondary outcome). The mean values were compared at the 0.05 significance level. RESULTS: The P+D group showed the most newly formed bone in histology and in micro-CT analyses. L-PRF was more effective in bone regeneration when compared to nonresorbable and resorbable barrier membranes. Additionally, this study indicated DBBM was the more favorable osseous graft material for bone regeneration than ß-TCP when barrier membranes are used. CONCLUSION: From the results of this in vivo study using surgically created defects, L-PRF plays an effective role as a barrier membrane for lateral ridge augmentation. L-PRF may be an excellent barrier membrane in place of other nonresorbable and resorbable membranes.

A retrospective study of implants placed following 1-stage or 2-stage maxillary sinus floor augmentation by the lateral window technique performed on residual bone of <4 mm: Results up to 10 years of follow-up.

BACKGROUND: The purpose of this study was to compare the survival rates of implants placed following 1-stage or 2-stage maxillary sinus floor augmentation by the lateral window technique (SFALW) performed on residual bone of <4 mm. METHODS: This study was conducted based on dental records and radiographs obtained from patients who received SFALW from March 2006 to June 2014, being followed up between March 2006 and December 2017. They were divided into 1-stage and 2-stage groups according to the SFALW performed. Statistical analysis was performed to evaluate whether a significant difference existed between 1-stage and 2-stage SFALW in terms of survival rates. Multivariable logistic regression analysis was used to examine the influence of multiple variables on implant failure. RESULTS: A total of 395 implants (156 implants in the 1-stage group, 239 implants in the 2-stage group) in 167 patients fulfilled the inclusion criteria. Among them, 13 implants (five implants in the 1-stage group, eight implants in the 2-stage group) failed. No significant difference was found in the 10-year cumulative survival rate of implants between the 1-stage group and the 2-stage group (96.8% and 92.5%, respectively, P = 0.656). Multivariable logistic regression analysis demonstrated that implant failure was significantly influenced by implant length and functional time following prosthetic loading. CONCLUSIONS: The 10-year cumulative survival rates showed no statistically significant difference between implants following 1-stage and 2-stage maxillary SFALW performed on residual bone height of <4 mm.

Diagnostic Models for Screening of Periodontitis with Inflammatory Mediators and Microbial Profiles in Saliva.

This study aims to investigate and assess salivary biomarkers and microbial profiles as a means of diagnosing periodontitis. A total of 121 subjects were included: 28 periodontally healthy subjects, 24 with Stage I periodontitis, 24 with Stage II, 23 with Stage III, and 22 with Stage IV. Salivary proteins (including active matrix metalloproteinase-8 (MMP-8), pro-MMP-8, total MMP-8, C-reactive protein, secretory immunoglobulin A) and planktonic bacteria (including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum, Prevotella intermedia, Porphyromonas nigrescens, Parvimonas micra, Campylobacter rectus, Eubacterium nodatum, Eikenella corrodens, Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Actinomyces viscosus) were measured from salivary samples. The performance of the diagnostic models was assessed by receiver operating characteristics (ROCs) and area under the ROC curve (AUC) analysis. The diagnostic models were constructed based on the subjects' proteins and/or microbial profiles, resulting in two potential diagnosis models that achieved better diagnostic powers, with an AUC value > 0.750 for the diagnosis of Stages II, III, and IV periodontitis (Model PA-I; AUC: 0.796, sensitivity: 0.754, specificity: 0.712) and for the diagnosis of Stages III and IV periodontitis (Model PA-II; AUC: 0.796, sensitivity: 0.756, specificity: 0.868). This study can contribute to screening for periodontitis based on salivary biomarkers.

Influence of microgroove dimension on cell behavior of human gingival fibroblasts cultured on titanium substrata.

OBJECTIVE: The purpose of this study was to determine the dimension of surface microgrooves on titanium (Ti) substrata that shows the greatest positive influence on characterizing specific cell behavior of cultured human gingival fibroblasts. MATERIAL AND METHODS: Commercially pure Ti disks with surface microgrooves of monotonous 3.5 mm in depth and respective 15, 30, and 60 microm in width were fabricated using photolithography and used as the culture substrata in the three experimental groups in this study (TiD15, TiD30, and TiD60 groups), whereas the smooth Ti disk was used as the control substrata (smooth Ti group). Human gingival fibroblasts were cultured on the four groups of Ti substrata on successive timelines. Cell behaviors, such as adhesion, morphology,viability and proliferation, and gene expression were analyzed and compared between all groups using crystal violet stain, scanning electron microscopy (SEM), XTT assay, and reverse transcriptase-polymerase chain reaction, respectively. RESULTS: SEM demonstrated that cells were able to readily descend into the microgrooves of TiD30 at the early phase of culture. Cells on the ridge edges or in groove corners were spindle shaped with abundant filopodia formation toward the acid-etched surface inside the microgrooves, thus mimicked the cell shape in three-dimensional (3D) nanoenvironment. TiD15 significantly increased the cell viability and proliferation compared with the smooth Ti substrata after 72 h of culture. Up-regulation of fibronectin(FN) and alpha5 integrin genes was noted in cells cultured on TiD15 and TiD30. Gene expression pattern specific to the cells in 3D-matrix culture, such as down-regulation of alpha-smooth muscle actin gene along with up-regulation of FN and p21 genes, was pronounced in cells cultured on TiD30. CONCLUSION: This study indicates that surface microgrooves of both 15 and 30 microm in widt hand a monotonous 3.5 microm in depth on Ti substrata increase various cell behaviors of cultured human gingival fibroblasts.

The efficacy of a double-layer collagen membrane technique for overlaying block grafts in a rabbit calvarium model.

OBJECTIVES: To analyze the outcomes of a single- and a double-layered collagen membrane on the efficacy of onlay block grafts in terms of bone resorption and augmentation. MATERIAL AND METHODS: A total of 36 New Zealand white rabbits were used in this study. Calvarial bone blocks were obtained from one side of the parietal bone and fixed on the contaralateral side. The onlay grafts were covered with either no (C group), one (M1 group), or two (M2 group) layers of a non-cross-linked collagen membrane (BioGide((R))). After 2, 4, and 6 months of healing, rabbits were sacrificed and explanted specimens were prepared for histologic and histomorphometric analysis. At each period, the overall pattern of graft bone resorption and membrane biodegradation were examined histologically, and the sustained external form of grafted bone (%) and the remaining mineralized bone volume (%) were measured histomorphometrically. RESULTS: The M1 and M2 groups exhibited decreased bone resorption compared with the C group at all periods. The M2 group had less graft resorption and a higher bone density of the grafted bone than the M1 group. In the M1 group, the collagen membrane was degraded partially or completely by 4 months and was absent at 6 months. Conversely, for the M2 group, the membrane body was retained up to 6 months. CONCLUSIONS: Our results demonstrated that the collagen membrane used here can reduce graft bone resorption. Furthermore, the double-layer technique using non-cross-linked collagen membranes (BioGide((R))) can enhance the efficacy of the onlay block bone graft technique in terms of both bone resorption and augmentation compared with a single-layer collagen membrane.

Regenerated Bone Pattern Around Exposed Implants with Various Designs.

PURPOSE: The design and surface features of dental implants substantially affect the healing and remodeling of adjacent bones. This study aimed to investigate the impact of design and surface on bone regeneration using implants of two different pitches, each with three different surface features. MATERIALS AND METHODS: Custom-manufactured titanium implants (length, 10 mm; diameter, 3.5 mm) were divided along the major axis into two sections: one with 0.6-mm pitch and the other with 0.4-mm pitch. They were processed by turned, blasting and etching, and anodic oxidation surface treatments and implanted into rabbit tibia. The upper 4 mm of the inserted implants was exposed, and bone regeneration was induced around the exposed area using a titanium chamber (height: 4 mm) containing particulate autogenous and bovine bone. After a 12-week healing period, the quantity and quality of bone regeneration around the implants were evaluated. Thirty specimens-10 specimens each from the turned, blasting and etching, and anodic oxidation surface groups with 0.6- and 0.4-mm pitch sizes- were evaluated by histomophometric analysis. RESULTS: The vertical height and width of regenerated bone around blasting and etching and anodic oxidation surfaces were significantly greater than those around turned implants (P < .05); the vertical heights of regenerated bone around the 0.4-mm-pitch sections of blasting and etching and anodic oxidation surfaces were significantly greater than those around the 0.6-mm-pitch sections (P < .05). Both blasting and etching and anodic oxidation surfaces exhibited significantly greater bone-to-implant contact and bone volume at the implant thread than turned implants (P < .05). However, there was no significant difference between the 0.6- and 0.4-mm-pitch sections. CONCLUSION: The findings of this study indicate that blasting and etching and anodic oxidation surfaces with a 0.4-mm-pitch design result in greater vertical ingrowth of regenerated bone than those with a 0.6-mm-pitch design.

The bactericidal effect of an atmospheric-pressure plasma jet on Porphyromonas gingivalis biofilms on sandblasted and acid-etched titanium discs.

PURPOSE: Direct application of atmospheric-pressure plasma jets (APPJs) has been established as an effective method of microbial decontamination. This study aimed to investigate the bactericidal effect of direct application of an APPJ using helium gas (He-APPJ) on Porphyromonas gingivalis biofilms on sandblasted and acid-etched (SLA) titanium discs. METHODS: On the SLA discs covered by P. gingivalis biofilms, an APPJ with helium (He) as a discharge gas was applied at 3 different time intervals (0, 3, and 5 minutes). To evaluate the effect of the plasma itself, the He gas-only group was used as the control group. The bactericidal effect of the He-APPJ was determined by the number of colony-forming units. Bacterial viability was observed by confocal laser scanning microscopy (CLSM), and bacterial morphology was examined by scanning electron microscopy (SEM). RESULTS: As the plasma treatment time increased, the amount of P. gingivalis decreased, and the difference was statistically significant. In the SEM images, compared to the control group, the bacterial biofilm structure on SLA discs treated by the He-APPJ for more than 3 minutes was destroyed. In addition, the CLSM images showed consistent results. Even in sites distant from the area of direct He-APPJ exposure, decontamination effects were observed in both SEM and CLSM images. CONCLUSIONS: He-APPJ application was effective in removing P. gingivalis biofilm on SLA titanium discs in an in vitro experiment.

Biomodification of compromised extraction sockets using hyaluronic acid and rhBMP-2: An experimental study in dogs.

BACKGROUND: This experimental study aims to evaluate the effect of hyaluronic acid on healing of infected extraction sockets compared with recombinant human bone morphogenetic protein-2 (rhBMP-2). METHODS: Both third and fourth mandibular premolars of six beagle dogs were hemisected, and the distal roots were extracted at baseline. Subsequently, combined endodontic-periodontic lesions were induced at the remaining mesial roots. After 4 months, the mesial roots on both sides of the mandible were removed. Four sockets per dog were randomly allocated to four groups: Group 1, Control; Group 2, only absorbable collagen sponge (ACS: carrier); Group 3, 1% hyaluronic acid (HA) gel + ACS; and Group 4, rhBMP-2 + ACS. After 3 months of healing, the dogs were euthanized for microcomputed tomography and histologic analysis. RESULTS: After the lesion induction period (4 months), communication between the periodontal lesion and endodontic periapical lesion was observed at all remaining mesial roots. Alveolar bone overgrowth was observed in groups 3 and 4, but bone volume density was not significantly different among all groups. At the crestal portion, mineralization, and osteocalcin expression were higher in groups 3 and 4 than in groups 1 and 2. CONCLUSION: Treatment with HA can promote bone formation and improve the wound healing rate comparable to rhBMP-2 in infected extraction sockets.

The Effect of Ultraviolet Photofunctionalization on a Titanium Dental Implant with Machined Surface: An In Vitro and In Vivo Study.

Ultraviolet (UV) photofunctionalization has been suggested as an effective method to enhance the osseointegration of titanium surface. In this study, machined surface treated with UV light (M + UV) was compared to sandblasted, large-grit, acid-etched (SLA) surface through in vitro and in vivo studies. Groups of titanium specimens were defined as machined (M), SLA, and M + UV for the disc type, and M + UV and SLA for the implant. The discs and implants were assessed using scanning electron microscopy, confocal laser scanning microscopy, electron spectroscopy for chemical analysis, and the contact angle. Additionally, we evaluated the cell attachment, proliferation assay, and real-time polymerase chain reaction for the MC3T3-E1 cells. In a rabbit tibia model, the implants were examined to evaluate the bone-to-implant contact ratio and the bone area. In the M + UV group, we observed the lower amount of carbon, a 0°-degree contact angle, and enhanced osteogenic cell activities (p < 0.05). The histomorphometric analysis showed that a higher bone-to-implant contact ratio was found in the M + UV implant at 10 days (p < 0.05). In conclusion, the UV photofunctionalization of a Ti dental implant with M surface attained earlier osseointegration than SLA.