Efficacy of dental floss in the management of gingival health: a randomized controlled clinical trial.

OBJECTIVES: This randomized controlled clinical trial evaluated the efficacy of dental floss as a supplement to toothbrushing in support of gingival health in adults. MATERIALS AND METHODS: Seventy-five systemically healthy subjects, non-smokers, without loss of interproximal periodontal attachment and with more than 15% of the interproximal sites presenting with gingival bleeding were randomized into two groups either performing toothbrushing supplemented by dental floss (TB + DF) or toothbrushing (TB) alone. Over a 60-day period, participating subjects weekly received oral hygiene instruction and supervised personal and professional plaque removal by applying the devices assigned for the group. Study subjects were instructed to perform toothbrushing twice daily (group TB + DF and TB) and use dental floss once daily (group TB + DF). Gingival Index (GI) and Plaque Index (PlI) were evaluated at baseline, and at 30 and 60 days. Linear mixed models were used to compare PlI and GI intra- and intergroup means. RESULTS: Interproximal gingival inflammation (GI = 2 and mean GI) was significantly reduced in both groups by day 30, reduction in inflammation being significantly greater in the TB + DF compared with the TB alone group. No further significant alterations were observed by day 60. Moreover, reduction in gingival inflammation (GI = 2) was greater in the anterior compared with the posterior dentition. CONCLUSIONS: Interproximal gingival inflammation may be significantly reduced by toothbrushing alone, the effect being significantly enhanced when toothbrushing is combined with dental floss. TRIAL REGISTRATION: The protocol registration was filed on May 9, 2018 (# 538,311,716.5.0000.5346) on ClinicalTrials.gov and after complete registration, a NCT number was generated (NCT04909840). Since the date in May 2018 when the protocol preregistration was filed, no change in methodology, primary outcome, and data analysis has occurred. CLINICAL RELEVANCE: Optimized personal oral hygiene routines in individuals without loss clinical attachment interproximal should include dental floss as a supplement to toothbrushing in support of gingival health.

Overlay Analysis of Cone-Beam Computed Tomography Volumes Acquired before and after Horizontal Alveolar Ridge Augmentation.

OBJECTIVE: The objective of this study was to illustrate the efficacy of a novel imaging analysis technology to capture horizontal and vertical dimensional changes following horizontal alveolar ridge augmentation (HRA). METHODS: Cone-beam computed tomography (CBCT) volumes from 65 HRA sites in 57 patients were available for evaluation, employing a three-dimensional analysis software to overlay preoperative and post-augmentation CBCT volumes. Horizontal and vertical alveolar ridge dimensional (HRD/VRD) changes were recorded considering a panel of patient-, site-, and procedure-related explanatory variables. RESULTS: VRD changes ranged from -2.9 to 3.0 mm, more than half anterior sites losing alveolar ridge height. Mean HRD increase at the 3- and 5-mm levels apical to the alveolar crest amounted to 2.3±1.6 and 2.4±1.3 mm, respectively, membrane fixation and non-resorbable membrane use associated with significantly greater gains. CONCLUSIONS: To date, studies reporting dimensional changes following HRA predominantly rely on serial in situ orofacial caliper recordings omitting vertical alterations. The protocol employed in this study allows simultaneous HRD and VRD evaluations and assures baseline and post-augmentation recordings are made at the same alveolar ridge position. Compared with in situ recording, CBCT overlay analysis may achieve a more complete characterization of dimensional changes following HRA.

Correlation between dental plaque accumulation and gingival health in periodontal maintenance patients using short or extended personal oral hygiene intervals.

AIMS: To evaluate the correlation between bacterial dental plaque accumulation and gingival health in subjects with history of periodontitis attending a maintenance programme including personal oral hygiene measures (pOH) at short and extended intervals. This study is a secondary analysis of a randomized clinical trial. MATERIALS AND METHODS: Forty-two subjects were randomized into groups performing pOH at 12-, 24- or 48-h intervals. The Plaque Index (PlI), Gingival Index (GI) and bleeding on probing (BoP) were recorded at baseline, 30 and 90 days. For the analysis, pOH groups were collapsed into subjects performing pOH at daily (G12/24) or extended (G48) intervals. Summary statistics and Spearman correlations between plaque accumulation and gingival inflammation are presented. RESULTS: G12/24 and G48 subjects showed significant increases in plaque scores and percentage sites with gingival inflammation over the course of study. At 90 days, G48 subjects showed significantly greater GI and BoP scores than G12/24 subjects. While PlI/GI correlations were not affected by pOH interval, PlI/BoP correlations remained unchanged with short to increase with extended pOH intervals. CONCLUSION: pOH interval influences the correlation between bacterial dental plaque accumulation and gingival inflammation. Subjects using extended pOH intervals exhibit an increased correlation allowing accumulation of bacterial dental plaque to the detriment of gingival health. (ClinicalTrials.gov: 50208115.9.0000.5346). Clinical Trials: ClinicalTrials.gov: NCT02684682.

Microbiologic effect of two topical anti-infective treatments on ligature-induced peri-implantitis: A pilot study in dogs.

BACKGROUND: The aim of this split-mouth design pilot study in dogs was to assess microbiologic effects of two topical anti-infective treatment protocols on dental implants subjected to ligature-induced peri-implantitis, without use of systemic antibiotics. METHODS: Eight adult Beagle dogs each received four dental implants in contralateral, edentulated, mandibular jaw quadrants. After 8 weeks, silk ligatures were installed, to be removed after another 8 weeks. After 6 additional weeks, induced peri-implantitis lesions were subjected to either antimicrobial photodynamic therapy (aPDT) or a topical tetracycline (TTC) hydrochloride (50 mg/mL) solution. Microbiologic samples were collected from the deepest proximal peri-implantitis site in each jaw quadrant before and after treatment. The samples were analyzed using DNA-DNA hybridization checkerboard technique. RESULTS: Peri-implantitis induction successfully produced lesions with microbiologic characteristics similar to those found in humans. Overall results showed effective bacterial count reductions for both protocols. aPDT demonstrated major reductions of the red complex, but no statistical differences between groups were observed when adjusted for multiple comparisons. CONCLUSION: aPDT and TTC successfully decontaminated infected implant surfaces. Implant decontamination with aPDT appears to be a viable alternative to TTC in the management of peri-implantitis infection.

Bone tissue response following local drug delivery of bisphosphonate through titanium oxide nanotube implants in a rabbit model.

OBJECTIVES: The objective of this study was to evaluate whether surface chemistry-controlled TiO2 nanotube structures may serve as a local drug delivery system for zoledronic acid improving implant-bone support. METHODS: Twenty-four screw-shaped Ti implants with surface chemistry-controlled TiO2 nanotube structures were prepared and divided into a zoledronic acid-formatted test and a native control group. The implants were inserted into contra-lateral femoral condyles in 12 New Zealand White rabbits. Bone support was evaluated using resonance frequency analysis (RFA) and removal torque (RTQ), as well as histometric analysis following a 3-weeks healing interval. RESULTS: Zoledronic acid-formatted TiO2 nanotube test implants showed significantly improved implant stability and osseointegration measured using RFA and RTQ compared with control (p < 0.05), and showed significantly enhanced new bone formation within the root of the threads compared with control (p < 0.05). CONCLUSIONS: TiO2 nanotube implants may prove to be a significant delivery system for drugs or biologic agents aimed at supporting local bone formation. Additional study of candidate drugs/agents, optimized dosage and release kinetics is needed prior to evaluation in clinical settings.

Periodontal and endodontic pathology delays extraction socket healing in a canine model.

PURPOSE: The aim of the present exploratory study was to evaluate extraction socket healing at sites with a history of periodontal and endodontic pathology. METHODS: The mandibular 4th premolar teeth in 5 adult beagle dogs served as experimental units. Periodontal and endodontic lesions were induced in 1 premolar site in each animal using wire ligatures and pulpal exposure over 3 months (diseased sites). The contralateral premolar sites served as healthy controls. The mandibular 4th premolar teeth were then extracted with minimal trauma, followed by careful wound debridement. The animals were sacrificed at days 1, 7, 30, 60, and 90 post-extraction for analysis, and the healing patterns at the healthy and diseased extraction sites were compared using radiography, scanning electron microscopy, histology, and histometry. RESULTS: During the first 7 days of healing, a significant presence of inflammatory granulation tissue was noted at the diseased sites (day 1), along with a slightly accelerated rate of fibrin clot resolution on day 7. On day 30, the diseased extraction sites showed a greater percentage of persistent fibrous connective tissue, and an absence of bone marrow formation. In contrast, healthy sites showed initial signs of bone marrow formation on day 30, and subsequently a significantly greater proportion of mature bone marrow formation on both days 60 and 90. Radiographs exhibited sclerotic changes adjoining apical endodontic lesions, with scanning electron microscopy showing collapsed Volkmann canals protruding from these regions in the diseased sites. Furthermore, periodontal ligament fibers exhibited a parallel orientation to the alveolar walls of the diseased sites, in contrast to a perpendicular arrangement in the healthy sites. CONCLUSIONS: Within the limitations of this study, it appears that a history of periodontal and endodontic pathology may critically affect bone formation and maturation, leading to delayed and compromised extraction socket healing.

Is ridge preservation/augmentation at periodontally compromised extraction sockets safe? A retrospective study.

OBJECTIVES: This study aimed to evaluate the safety of ridge preservation/augmentation procedures when performed at compromised extraction sockets. METHODS: Patients subject to ridge preservation/augmentation at periodontally compromised sockets at Seoul National University Dental Hospital (SNUDH) were evaluated in a chart review. Tooth extractions due to acute infection were not included in our study as chronically formed lesions are the only lesions that can be detected from radiographic images. If inflammatory symptoms persisted following ridge preservation/augmentation and antimicrobial and anti-inflammatory therapy, the patient was categorized as a re-infection case and implanted biomaterial removed. RESULTS: Of 10,060 patients subject to tooth extractions at SNUDH, 2011 through 2015, 297 cases meeting inclusion criteria were reviewed. The severity and type of lesions were not specific because extracting data was only done by radiographic images and chart records. The review identified eight patients exhibiting inflammatory symptoms that required additional antimicrobial and anti-inflammatory therapy. Within this group, re-infection occurred in two patients requiring biomaterials removal. The final safety rate for the ridge preservation/augmentation was 99.3%. None of the demographic factors, systemic conditions or choice of biomaterial affected the safety of ridge preservation/augmentation. CONCLUSION: Alveolar ridge preservation/augmentation at periodontally compromised sockets appears safe following thorough removal of infectious source.

Sinus augmentation using a mini-pig model: Effect of ceramic and allogeneic bone biomaterials.

BACKGROUND: Present clinical practice broadly relies on off-the-shelf allogeneic, xenogeneic or synthetic bone biomaterials in support of sinus augmentation. Also, recombinant human bone morphogenetic protein-2 in an absorbable collagen sponge carrier (rhBMP-2/ACS) has been shown to support clinically relevant bone formation when used to augment the maxillary sinus. OBJECTIVES: To evaluate local bone formation/dental implant osseointegration following implantation of two particulate bone biomaterials using the mini-pig sinus augmentation model. METHODS: Nine adult Göttingen mini-pigs were used for evaluation of a biphasic ceramic (15%/85% HA/ß-TCP) and an allogeneic mineralized bone biomaterial. Treatments randomized to contralateral sinus sites included sham-surgery (control) and biomaterials. Two threaded dental implants (ø4.0 × 11.5 mm) were placed at each sinus site. The animals were euthanized at 8 weeks for histologic analysis. RESULTS: Execution of the surgical protocol and healing was unremarkable. Limited infraorbital swelling was observed until suture removal. The biphasic ceramic and allogeneic bone biomaterials produced significantly increased bone formation (5.2 ± 1.9 mm and 4.9 ± 1.6 mm vs. 2.6 ± 0.5 mm, p < 0.05) and osseointegration (18.0 ± 6.0% and 25.1 ± 18.2% vs. 10.1 ± 8.0%, p < 0.05) over the sham-surgery control. No significant differences were observed between biomaterials. CONCLUSIONS: Implantation of biphasic ceramic or allogeneic bone biomaterials enhances bone formation in the mini-pig maxillary sinus, however, dental implant bone support is incomplete resulting in overall limited osseointegration.

Comparison between two antimicrobial protocols with or without guided bone regeneration in the treatment of peri-implantitis. A histomorphometric study in dogs.

OBJECTIVES: This study used a dog model to evaluate two antimicrobial protocols with or without guided bone regeneration (GBR) in the surgical reconstruction of peri-implantitis defects. MATERIAL AND METHODS: Eight beagle dogs subject to ligature-induced peri-implantitis were used. The animals either received antimicrobial photodynamic therapy or topical tetracycline hydrochloride combined with GBR or as stand-alone surgical interventions. Block biopsies of the defect sites for histological analysis were obtained at euthanasia, 12 weeks postsurgery. The primary outcome of the study was re-osseointegration; secondary outcomes included alveolar bone gain and remaining defect characteristics. The effects of the implant site, early exposure, and type of antimicrobial protocol on bone regeneration were also evaluated. RESULTS: No significant differences were observed between the two antimicrobial protocols, and the adjunctive use of GBR failed to significantly improve re-osseointegration or bone gain using either protocol. Buccal sites and implant early exposure negatively affected bone regeneration. CONCLUSION: Both antimicrobial therapies stand-alone or combined with GBR allowed similar and limited bone gain.

Effect of Platform Shift/Switch on Crestal Bone Levels and Mucosal Profile Following Flapless Surgery and Crestal/Subcrestal Implant Placement.

BACKGROUND: Crestal remodeling/bone loss appears a common sequel to dental implant placement. Several hypotheses and clinical strategies have been advanced to explain and avert crestal remodeling; however, causative mechanisms remain unclear and the efficacy of clinical protocol uncertain. OBJECTIVE: The objective of the present study was to provide a histologic record of crestal versus subcrestal implant placement on crestal remodeling and mucosal profile comparing platform shift/switch and standard abutments following flapless implant surgery using a dog model. METHODS: Four dental implants each were placed into the left and right edentulated posterior mandibles in five adult male hound-Labrador mongrel dogs using a flapless approach including crestal versus subcrestal placement and using platform shift versus standard abutments. Block biopsies were collected for histological/histometric analysis following an 8-week healing interval. RESULTS: Both crestal and subcrestal implant installation resulted in significant crestal remodeling and bone loss, in particular at buccal sites, without significant differences between platform shift/switch and standard abutments. Implants installed subcrestally exhibited a significantly taller mucosal profile over crestal-level implants without significant differences between platform shift/switch and standard abutments; the epithelial attachment at all times arrested on the abutment surface. CONCLUSIONS: Comparing platform shift/switch versus standard abutments using a minimally invasive flapless approach including crestal or subcrestal implant placement, the platform shift/switch abutments offer no selective advantage over standard abutments.

Effect of Platform Shift on Crestal Bone Levels and Mucosal Profile Following Flap Surgery and Subcrestal Implant Placement in Presence/Absence of Gap Defects.

BACKGROUND: Physiologic remodeling resulting in crestal bone loss appears a common corollary to dental implant surgery. Several hypotheses and clinical strategies have been advanced to explain and avert crestal remodeling; however, causative mechanisms remain unclear and the efficacy of clinical protocols uncertain. PURPOSE: The objective of the present study was to provide a histologic account of crestal bone levels and mucosal profile at implant sites receiving platform shift/switch and standard abutments following conventional flap surgery and subcrestal implant placement in presence or absence of crestal gap defects using a dog model. MATERIALS AND METHODS: Four dental implants were placed into the left/right edentulated posterior mandible in five adult male Hound Labrador mongrel dogs using flap surgery including subcrestal placement with/without a 1 × 5 mm (width × depth) gap defect, and using platform shift/switch and standard abutments. Block biopsies were collected for histological/histometric analysis following an 8-week healing interval. RESULTS: No significant differences in crestal resorption were observed among experimental groups; crestal resorption being significantly more advanced at buccal than at lingual sites (p < .001). Similarly, crestal bone-implant contact was not significantly different among groups; crestal bone-implant contact being consistently below the implant platform at buccal sites (p < .01). Moreover, the peri-implant mucosal profile was not statistically different among groups, the mucosal height being significantly greater at buccal than at lingual sites (p < .001). Also, no significant differences among groups were observed for the apical extension of the epithelial attachment, the epithelial attachment being arrested more than 2 mm above the implant platform at both platform shift/switch and standard abutments. CONCLUSIONS: Using a clinical strategy including flap surgery and subcrestal implant placement, implant technology comparing platform shift/switch with standard abutments, surgical approach, and abutment selection seems to have a limited impact on crestal remodeling, associated bone loss, and mucosal profile.

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.

Effect of Platform Shift/Switch and Concave Abutments on Crestal Bone Levels and Mucosal Profile following Flap and Flapless Implant Surgery.

BACKGROUND: Crestal remodeling/bone loss appears to be a common sequel to dental implant placement. Several hypotheses/clinical strategies have been proposed to explain/avert crestal remodeling; however, causative mechanisms remain unclear and the efficacy of these clinical approaches uncertain. OBJECTIVE: The objective of the present study was to provide a histological account of crestal bone levels and mucosal profile at platform shift/switch and concave abutments following flapless and conventional flap surgery and subcrestal implant placement using a dog model. METHODS: Four dental implants each were placed in the left/right mandibular posterior jaw quadrants in five adult male Hound/Labrador mongrel dogs using flap surgery with a 1 × 5 mm gap defect or using a flapless approach, both involving placement 2 mm subcrestally and platform shift/switch versus concave abutments. Block biopsies for histological/histometric analysis were collected at 8 weeks. RESULTS: No significant differences were observed regarding crestal bone levels, with all groups showing mean bone levels above the implant platform. Similarly, crestal bone-implant contact was not significantly different among groups. Moreover, peri-implant mucosal profiles were not statistically different among groups for buccal sites; average mucosal height reached 4.1 to 4.9 mm above the implant platform. Comparison between buccal and lingual sites showed a nonsignificant tendency toward greater crestal resorption at buccal sites, adjusting for other factors. Mean crestal bone-implant contact level approximated the implant platform for lingual sites while consistently remaining below the platform at the buccal sites. Peri-implant mucosal height was significantly higher at buccal than at lingual sites, with the epithelial attachment located a significant distance away from the implant platform at buccal sites. CONCLUSIONS: The surgical approaches (subcrestal implant placement by flap surgery or a flapless approach) and abutment designs (platform shift/switch or concave) used in this study seem to have a limited impact on crestal remodeling, associated bone loss, and mucosal profile. Bioclinical strategies should be developed to circumvent the limitations of current clinical protocol.

Wound healing following surgical and regenerative periodontal therapy.

Clinical studies have evaluated the effect of conventional periodontal surgical therapy. In general, although some clinical gain in tissue support may be attained, these therapies do not support regeneration of the periodontal attachment. Even though the biological possibility of periodontal regeneration has been demonstrated, the clinical application of this intrinsic potential appears difficult to harness; thus also conceptually most intriguing candidate protocols face clinical challenges. In this review, we explore the bioclinical principles, condiciones sine quibus non, that unleash the innate potential of the periodontium to achieve clinically meaningful periodontal regeneration (i.e. space-provision, wound stability and conditions for primary intention healing). Moreover, limiting factors and detrimental practices that may compromise clinical and biological outcomes are reviewed, as is tissue management in clinical settings.

Biodegradable polymer scaffolds loaded with low-dose BMP-2 stimulate periodontal ligament cell differentiation.

Poly(L-lactide)-co-(epsilon-caprolactone) [poly(LLA-co-CL)] and poly(L-lactide)-co-(1,5-dioxepan-2-one) [poly(LLA-co-DXO)] are being considered candidate scaffolds for bone tissue engineering. We evaluated the bioactive potential of poly(LLA-co-CL) and poly(LLA-co-DXO) scaffolds loaded with low-dose bone morphogenetic protein-2 (BMP-2). Periodontal ligament (PDL) cells were cultured onto the various scaffolds loaded with 1 µg BMP-2 or without BMP-2 (control). Cell viability, attachment, and proliferation were determined using a methylthiazol tetrazolium (MTT) colorimetric assay at day 1, 3, and 7. Scanning electron microscopy was used to analyze cell morphology at day 7. Cell differentiation was evaluated assaying alkaline phosphatase (ALP) activity at day 7, 14, and 21. Real-time PCR was used to evaluate the mRNA expression of periostin, ALP, type I collagen, bone sialoprotein and BMP-2. A commercially available enzyme-linked immunosorbent assay was used to assess BMP-2 production. Surface analysis disclosed excellent cell attachment, spread, and penetration into the porous scaffolds. The MTT assay indicated that scaffolds loaded with low concentration of BMP-2 did not influence the viability of cells. Cells grown on the modified scaffolds expressed higher levels of osteogenic markers than the nonmodified scaffolds (p<0.05). Poly(LLA-co-CL) and poly(LLA-co-DXO) scaffolds loaded with low-dose BMP-2 exhibited a significant effect stimulating PDL differentiation suggesting a continued evaluation in relevant in vivo models.

Alveolar ridge and maxillary sinus augmentation using rhBMP-2: a systematic review.

PURPOSE: The aim of this systematic review was to evaluate clinical and safety data for recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier when used for alveolar ridge/maxillary sinus augmentation in humans. MATERIALS AND METHODS: Clinical studies/case series published 1980 through June 2012 using rhBMP-2/ACS were searched. Studies meeting the following criteria were considered eligible for inclusion: >10 subjects at baseline and maxillary sinus or alveolar ridge augmentation not concomitant with implant placement. RESULTS: Seven of 69 publications were eligible for review. rhBMP-2/ACS yielded clinically meaningful bone formation for maxillary sinus augmentation that would allow placement of regular dental implants without consistent differences between rhBMP-2 concentrations. Nevertheless, the statistical analysis showed that sinus augmentation following autogenous bone graft was significantly greater (mean bone height: 1.6 mm, 95% CI: 0.5-2.7 mm) than for rhBMP-2/ACS (rhBMP-2 at 1.5 mg/mL). In extraction sockets, rhBMP-2/ACS maintained alveolar ridge height while enhancing alveolar ridge width. Safety reports did not represent concerns for the proposed indications. CONCLUSIONS: rhBMP-2/ACS appears a promising alternative to autogenous bone grafts for alveolar ridge/maxillary sinus augmentation; dose and carrier optimization may expand its efficacy, use, and clinical application.

Effects of implant drill wear, irrigation, and drill materials on heat generation in osteotomy sites.

This study evaluated the effects of drill wear on bone temperature during osteotomy preparation with 3 types of drills and compared heat production between drills. The drills used in this study were titanium nitride-coated metal, tungsten carbide carbon-coated metal, and zirconia ceramic drills. An osteotomy 11 mm in depth was formed in bovine scapular bone following the manufacturer's recommended drill sequences. Drilling was performed without irrigation and repeated 20 times; temperature was measured every 5 times. Next, 200 rounds of drilling during irrigation were performed for each drill, with temperature change monitored until round 200. Analysis of variance statistics were used for analyses of the measured data. Drilling without irrigation showed significant thermal increase at all time points compared to drilling with irrigation (P < .001). No significant difference was found between drill materials. Under irrigation, the frequency of previous drilling had minimal effects on thermal change. The repeated-measures analysis of variance revealed major thermal change at the initial time point (P < .0001), and the multiple comparison tests revealed a significant difference in temperature between the initial drills that had been used 50 or fewer times and those that had been used more than 50 times, irrespective of the drill material. The results of this study indicate that the initial drill should be changed in osteotomy preparation with irrigation after they have been used 50 times. Irrigation may be a more critical factor for the control of temperature elevation than is the drill material.

Effect of rhBMP-2 dose on bone formation/maturation in a rat critical-size calvarial defect model.

BACKGROUND: Application of recombinant human bone morphogenetic protein-2 (rhBMP-2) has been associated with significant adverse events in craniofacial settings, including swelling and seroma formation. Recent work has demonstrated an inverse relationship between bone formation/maturation and rhBMP-2 dose, frequency/severity of adverse events increasing with rising dose. OBJECTIVE: The objective of this study was to determine the most effective dose for rhBMP-2 soak-loaded onto an absorbable collagen sponge (ACS) carrier for bone formation/maturation using an established defect model. METHODS: One hundred sixty-eight outbred male Sprague-Dawley rats, age 11-13 weeks, weight 325-375 g randomized into seven groups of 24 subdivided into groups of eight, were used to provide radiographic and light microscopy observations of bone formation/maturation and aberrant healing events at 2, 4 and 8 weeks following application of rhBMP-2/ACS into critical-size, ø8-mm, through-through, calvarial osteotomy defects for a dose of 1.25, 2.5, 5.0, 10.0 and 20.0 µg rhBMP-2/defect, or serve as ACS or sham-surgery controls. RESULTS: rhBMP-2 dosages ≥ 2.5 µg/defect showed histological defect closure >90% within 2 weeks, and complete resolution within 4 weeks. Adverse healing events including swelling, excessive bone formation or seroma formation could not be determined with certainty in this defect model. Notably ACS control sites showed complete defect closure at the 8-week healing interval. CONCLUSIONS: rhBMP-2/ACS accelerates local bone formation in the rat critical-size through-through calvarial defect model once reaching an osteoinductive dose threshold. This threshold may already be reached at a 1.25-/2.5-µg dose in this model. No further enhancement to bone formation/maturation may be observed adding rhBMP-2 above the 2.5-µg dose. The 1.25-20.0 µg dose range did not invoke appreciable aberrant healing events.

Growth/differentiation factor-5: pre-clinical and clinical evaluations of periodontal regeneration and alveolar augmentation--review.

AIM: Growth/differentiation factor-5 (GDF-5) plays critical roles in mesenchymal cell differentiation and stimulates human periodontal ligament cell proliferation. Potentially, GDF-5 may also play roles in wound healing including periodontal regeneration and alveolar augmentation. The objective of this review was to provide up-to-date information from pre-clinical/clinical studies evaluating GDF-5 for these indications. METHODS: A comprehensive search using PubMed and Google search engines was conducted to identify reports on GDF-5 applied to periodontal and alveolar indications. Two reviewers independently screened the titles and abstracts from a total of 479 reports. Full-length articles of 17 pre-clinical and four clinical studies were selected and reviewed. RESULTS: Canine-, porcine- and non-human primate-based models as well as human clinical trials were used in the evaluation of GDF-5 in support of periodontal regeneration and alveolar augmentation. An absorbable collagen sponge (ACS), ß-tricalcium phosphate (ß-TCP) and a poly(lactic-co-glycolic) acid (PLGA) were evaluated as candidate carriers for GDF-5 using various dose and healing intervals demonstrating significantly enhanced periodontal regeneration/alveolar augmentation including cementum, periodontal ligament and alveolar bone with limited, if any, adverse effects. CONCLUSION: Growth/differentiation factor-5 supports periodontal regeneration/alveolar augmentation without aberrant healing events documented in qualified pre-clinical models and clinical pilot studies. In perspective, GDF-5 appears a promising technology for periodontal regeneration/alveolar augmentation.

Extraction sockets: erratic healing impeding factors.

AIM: The aim of this exploratory study was to analyse prevalence of extraction sockets showing erratic healing and evaluate factors potentially impeding healing. METHODS: Erratic healing was defined as extraction sites showing clinical observations of fibrous scar tissue occupying the extraction site rather than bone following 12 or more weeks of healing. Computerized tomography was used to evaluate characteristics and calculate Hounsfield unit scores for sites showing erratic healing. RESULTS: A total of 1226 dental records from Seoul National University Dental Hospital archives including patients subject to extractions prior to implant placement were evaluated. Seventy subjects (5.71%) and 97 sites (4.24%) exhibited erratic extraction socket healing. Maxillary incisor/canine sites showed the lowest (0.47%), whereas mandibular molar sites the highest (5.41%) occurrence. In the multivariable analysis, erratic healing was more likely to occur in subjects <60 years old (OR = 2.23, 95%CI = 1.26-3.94), subjects with hypertension (OR = 2.37, 95%CI = 1.24-4.55), in molar sites (OR = 4.91, 95%CI = 1.41-17.07), and following single tooth extractions (OR = 2.98, 95%CI = 1.36-6.53). Computerized tomography showed the highest incidence of bone loss for the buccal wall (49.3%). CONCLUSION: Erratic extraction socket healing appears a not uncommon sequel and local factors seem to be major contributors to its occurrence.