The adjunctive effect of polydeoxyribonucleotide on bone formation in alveolar ridge preservation: A pre-clinical in vivo study.

AIM: This study investigated the adjunctive effect of polydeoxyribonucleotide (PDRN) on bone formation in alveolar ridge preservation (ARP) sockets. MATERIALS AND METHODS: Both mandibular second, third and fourth premolars of eight beagle dogs were randomly divided into ARP and ARP/PDRN groups. Following tooth extraction, ARP procedures were conducted using collagenized alloplastic graft material and bilayer collagen membrane soaked with normal saline (ARP group) or PDRN (ARP/PDRN group) for 10 min before application. Both groups were also randomly allocated to 2-, 4- or 12-week healing subgroups. The primary endpoint of this study was to compare histomorphometric differences between ARP and ARP/PDRN. The secondary endpoints of this study were to compare micro-CT analysis and three-dimensional volumetric measurement between the two groups. RESULTS: In the histomorphometric analysis, the ARP/PDRN group exhibited greater new bone formation at coronal, middle and total position compared with the ARP group at 2-week healing. The number of newly formed blood vessels was higher in the ARP/PDRN group than in the ARP group at 2- and 4-week healing. In micro-CT analysis, the mean new bone volume/total bone volume between ARP and ARP/PDRN was statistically significant at 2-week healing. Ridge volume alterations were significantly decreased in the ARP/PDRN group during entire healing time compared with the ARP group, especially on the buccal side. CONCLUSIONS: The application of PDRN in ARP might provide additional benefits for early bone regeneration and maintenance of buccal ridge volume.

Association between toothbrushing and cardiovascular risk factors: a cross-sectional study using Korean National Health and Nutrition Examination Survey 2015-2017.

BACKGROUND: Previous studies have suggested that frequent toothbrushing is associated with a lower risk of future cardiovascular events. We sought to investigate further the relationship between toothbrushing, cardiovascular risk factors, and lifestyle behaviours. METHODS: We analysed a cross-sectional survey including 13,761 adults aged 30 years or older without a history of cardiovascular diseases from the Korean National Health and Nutritional Examination Survey. Conventional cardiovascular risk factors (blood pressure, lipid profiles, and fasting glucose), and inflammatory markers (high-sensitivity C-reactive protein [hsCRP], and white blood cell counts [WBC]) were investigated in relation to the frequency of toothbrushing. RESULTS: The estimated 10-year atherosclerotic cardiovascular disease (ASCVD) risk, calculated using the pooled cohort equations was 13.7%, 9.1%, and 7.3% for participants who reported toothbrushing 0-1, 2, and ≥ 3 times a day, respectively. Both conventional risk factors and inflammatory markers were significantly associated with frequent toothbrushing. However, after adjusting potential confounding factors such as age, sex, comorbidities, and lifestyle behaviours, only inflammatory markers were remained as significant factors. CONCLUSIONS: Oral hygiene behaviours are closely linked to cardiovascular risk factors. This study suggests that reduced systemic inflammatory burden may explain the benefit of improved oral hygiene in terms of cardiovascular risk.

Comparison of osteogenesis and osseointegration following implant placement with simultaneous maxillary sinus augmentation using particulate and collagenated block types of deproteinized porcine bone mineral: a radiographic and histomorphometric analysis.

OBJECTIVES: This study aimed to compare osseointegration and osteogenesis after single-stage maxillary sinus augmentation with the lateral window using particulate deproteinized porcine bone mineral (PDPBM) and collagenated block deproteinized porcine bone mineral (BDPBM). MATERIALS AND METHODS: Bi-maxillary premolars of six beagle dogs were extracted. Eight weeks later, an implant was placed into each augmented sinus with PDPBM or BDPBM according to a split-mouth design. Eight weeks later, all specimens were harvested. Each specimen was separated into the region of interest with the implant (ROI-I) and region of interest with sinus augmented area (ROI-S) 5 mm away from ROI-I. ROI-I and ROI-S were evaluated through micro-computed tomography and histomorphometry. RESULTS: Bone substitute insertion took longer for the PDPBM group than for the BDPBM group (P = 0.002). In ROI-I, three-dimensional bone-to-implant contact (BIC) did not show statistically significant differences between the groups. Two-dimensional BIC also showed comparable values for both groups. In ROI-S, the graft material volume/tissue volume, trabecular bone pattern factor, and structural model index were higher in the BDPBM group than in the PDPBM group (P < 0.05). The proportions of new bone, graft material, and connective tissue were not significantly statistically different between groups. Less new bone was found in the apical area than in the coronal or middle areas in the BCPBM group (P < 0.05). CONCLUSIONS: BDPBM may save time in inserting bone substitutes and provide comparable osteogenesis and osseointegration to PDPBM. CLINICAL RELEVANCE: When performing sinus augmentation, BDPBM might improve operator's convenience with comparable biological results compared to PDPBM.

Diagnostic performance of a point-of-care test device for periodontitis using human saliva: a single-center, single-blinded, confirmatory study.

OBJECTIVE: Recently, matrix metalloproteinase-8 (MMP-8) has been used to diagnose periodontal disease in a point-of-care (POC) test in order to save time and cost relative to the traditional diagnostic workflow. This study aimed to investigate the diagnostic performance of INCLIX TRF MMP-8, a POC testing device for periodontitis using the area under the receiver operating characteristic curve, sensitivity, specificity, and predictive values. MATERIALS AND METHODS: Full-mouth periodontal examination and radiographic analysis were used for evaluating periodontal condition based on the 2018 classification of periodontal disease. A dichotomous diagnosis of clinical periodontal condition was performed using the POC device. The relationships among periodontal condition and the concentration of MMP-8, tooth loss (TL), gingival index (GI), plaque index (PI), and alveolar bone loss (ABL) were assessed by the Spearman rank correlations (rs). RESULTS: In all, 108 cases of non-periodontitis (NP) and 191 cases of periodontitis (P), including 38 cases of periodontitis stage I, 42 cases of periodontitis stage II, 99 cases of periodontitis stage III, and 11 cases of periodontitis stage IV, were enrolled in this study. Diagnostic accuracy in assessing periodontal condition with the POC device improved when it was used with participants aged ≥ 40 years. There were weak positive correlations between periodontal condition and MMP-8 and between periodontal condition and GI (rs2 = 0.1124 and rs2 = 0.0906, respectively), whereas a strong positive correlation between periodontal condition and alveolar bone loss (rs2 = 0.6877) was observed. CONCLUSION: The POC device investigated in this study is a potential tool to distinguish between NP and P in individuals ≥ 40 years of age.

Dental students' self-evaluation comparison between dual dental education systems in Korea.

BACKGROUND: This study aimed to examine the satisfaction, educational linkage, and self-perceived competence of dental students enrolled in either 4 + 4 dental program, comprising an undergraduate degree and Doctor of Dental Surgery degree (DDS), or 3 + 4 program, which is a BS/DDS combined degree program, in the Korean dental education system. MATERIALS AND METHODS: The survey questionnaire using a 5-point Likert scale was developed and validated by four dental education experts, consisting of satisfaction with undergraduate courses, the interconnection of undergraduate courses with the DDS curriculum, and self-assessed core competency for dental graduates. A total of 252 students provided informed consent and voluntarily responded to the survey, among whom 109 students were in the 3 + 4 system and 143 were in the 4 + 4 system. Cronbach's correlation analysis and independent t-test were conducted for each evaluation item. RESULTS: Students' overall satisfaction level with the undergraduate education was higher in the 4 + 4 system than in the 3 + 4 system (P = 0.003). Students enrolled in the 4 + 4 system recognized that natural sciences are more connected to the graduate-level DDS program (P <  0.001), while the 3 + 4 students recognized that studies in medicine are closely interconnected to the DDS program (P = 0.001). There was almost no statistically significant difference in the students' perception of competency between the two education systems. DISCUSSION: Even though this study analyzed the case of a single university operating both 3 + 4 and 4 + 4 systems, it can be used as the groundwork for developing new opportunities and models of dental education system.

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.

Developing a clinical presentation dental education model and a pilot test.

INTRODUCTION: Accurate clinical decision-making of dentists should be based on their knowledge and experience. In the past 10 years, interest in competency-based dentistry education has rapidly increased, but there has been little attention paid to methods of improving dental education competency. The purpose of this study was to develop a clinical presentation education model that provides opportunities for students to practice problem-solving from the moment they greet the patient so that students can obtain the practical experience of competency-based education and the effectiveness of this model can be confirmed through pilot test. METHODS: This article is divided two parts: First, developing the clinical presentation dental education model (CPDEM) and Second, a pilot study adopted CPDEM. To confirm the effectiveness of this model, the students' satisfaction, their perception of self-achievement were analysed. RESULTS: Clinical presentation dental education model has been developed to provide practice-related education experience and provide linkage between basic science and clinical science. The result of applying this education model to 10 students as a pilot test was shown an overall high satisfaction level. In addition, self-achievement students' reported of all intended competencies was higher than for non-participating students of this model. CONCLUSIONS: This study focuses on practical education centring on clinical presentation. This model could get a meaningful and realistic experiences through the practice using clinical presentation of patients, use their metacognition for organizing and memorizing the patient's case by using concept map. It can be used as a future instructional method to enhance students' competency.

Periodontal Regeneration Using Recombinant Human Bone Morphogenetic Protein-2 and a Bilayer Collagen Matrix.

Previous studies demonstrated that recombinant human bone morphogenetic protein-2 (rhBMP-2) delivered using a collagen sponge could be a candidate for periodontal regeneration therapy. However, there is little evidence related to rhBMP-2 delivered with a bilayer collagen matrix. The aim of this study was to investigate the proper dose of rhBMP-2 using a bilayer collagen matrix for periodontal regeneration in a 1-wall defect. The mandibular first premolars and first molars of 6 beagle dogs were extracted, and an 8-week healing period was allowed. One-wall intrabony defects (4 mm in width and 5 mm in height) were made on the mesial side of the 2nd premolar and/or the distal side of the 4th premolar bilaterally. Subsequently, a bilayer collagen matrix containing 0 µg (C), 200 µg (T1), or 500 µg (T2) of lyophilized rhBMP-2 was randomly applied to the defect area. Calcein and xylenol orange were injected at 4 and 8 weeks following the surgery, respectively, to label periodic bone formation. After a 12-week healing period, the animals were sacrificed for micro-computed tomography and histomorphometric analysis. Bone mineral density and bone volume density showed statistically significant differences between the control group and group T1, while no significant differences were observed between the control group and group T2 or between groups T1 and T2. The bone height in groups T1 and T2 was smaller than that in the control group. Low doses of rhBMP-2 delivered using a bilayer collagen matrix in 1-wall intrabony defects can promote periodontal regeneration compared to no or high doses of rhBMP-2.

A randomized controlled clinical trial evaluating efficacy and adverse events of different types of recombinant human bone morphogenetic protein-2 delivery systems for alveolar ridge preservation.

OBJECTIVES: This 12-week clinical trial evaluated efficacy and adverse events for two recombinant human bone morphogenetic protein-2 (rhBMP-2) delivery systems in alveolar ridge preservation. MATERIALS AND METHODS: Sixty-four patients had a single tooth that required replacement with an implant, surrounded by > 50% alveolar bone height. Two cohorts (n = 32 patients each) were randomized to receive a rhBMP-2-soaked absorbable collagen sponge (test group), or ß-tricalcium phosphate and hydroxyapatite particles (control group) immersed in rhBMP-2, at the implant site. Bone height and width changes at 25%, 50%, and 75% of extraction socket level (ESL) were compared. Adverse events were assessed in the same period. In addition to the randomized controlled clinical trial, histological analysis of 21 patients (test group [n = 12], control group [n = 9]) was conducted, 4 months after alveolar ridge preservation. A non-inferiority test was used to analyze changes in alveolar bone height between groups (p = 0.05). A Wilcoxon rank-sum test was used to analyze changes in alveolar bone width and histomorphometric results between groups (p = 0.05). RESULTS: All patients showed good healing without severe adverse events. The lower limit of the one-sided 97.5% confidence interval in the difference between the two groups was 0.0033 (non-inferiority margin: -0.185); thus, the test group showed non-inferiority to the control group. Wilcoxon rank-sum test analysis did not show statistically significant differences between groups with regard to changes in alveolar bone width and histomorphometric analysis. CONCLUSIONS: The delivery systems showed similar efficacy for alveolar ridge preservation without severe adverse events.

Validity of a regenerative procedure for a minor bone defect with immediate implant placement: a systematic review and meta-analysis.

OBJECTIVE: This systematic review evaluates implant survival and the change in the width of the horizontal ridge following immediate implant placement with or without a regenerative procedure. MATERIALS AND METHODS: An electronic search of MEDLINE, EMBASE, and the LILACS database of the Cochrane Central Register of controlled trials was performed, along with a manual search, up to April 2018. Randomized controlled trials (RCTs) and quasi-randomized controlled clinical trials (CCTs) with >10 subjects were eligible for this systematic review. A meta-analysis of the risk difference in implant failure between the regenerative and non-regenerative procedure groups was performed using a fixed-effect model. In addition, a meta-analysis of the change in alveolar bone width was conducted using a fixed-effect model. RESULTS: Seven studies (six RCTs and one CCT) were included. A meta-analysis of three studies found no statistically significant risk difference in implant failure between the regenerative procedure and non-regenerative procedure groups. A meta-analysis of four studies showed that horizontal shrinkage of the alveolar ridge in the site of immediate implant placement was statistically significantly lower with the regenerative procedure than without it (<1 year follow up studies: weighted mean difference (WMD) 0.75 mm, 95% confidence interval 0.41-1.09, p < .00001; ≥1 year follow up study: WMD 1.22, 95% confidence interval 0.52-1.91, p = .00006; total: WMD 0.84 mm, 95% confidence interval 0.53-1.14, p < .00001). CONCLUSION: Within the study limitations, immediate implant placement with a regenerative procedure showed similar implant survival and less shrinkage of the ridge width than immediate implant placement without a regenerative procedure. Due to the high risk of bias and small sample sizes of the included studies, further clinical studies are warranted to draw definitive conclusions.

Comparison of immediate implant placement in infected and non-infected extraction sockets: a systematic review and meta-analysis.

OBJECTIVE: This review aimed to investigate the feasibility of immediate implant placement in infected extraction sockets. MATERIAL AND METHODS: We performed electronic and manual searches up to March 2017 to obtain data from randomized controlled trials (RCTs) and nonrandomized controlled clinical trials (CCTs). Using a fixed-effects model to assess the difference in survival rate (primary outcome), we evaluated the risk difference for immediate implant placement in infected and non-infected sites. We estimated the weighted mean differences (WMDs) of the change in marginal bone loss (MBL), probing depth (PD), modified bleeding index (mBI), marginal gingival level (MGL) and width of keratinized gingiva (WKG) at baseline and latest follow-up. RESULTS: In total, five studies (0 RCT, five CCTs) were included in the systematic review and three studies were included in the meta-analysis. The risk difference for immediate implant placement in an infected extraction socket compared with that in a non-infected socket was -0.02. WMDs for MBL, PD, mBI, MGL and WKG between the two groups were 0.32, 0.12, 0.07, -0.06, 0.20 and 0.51, respectively. No statistical differences were observed between the two groups, except for the change in WKG. CONCLUSIONS: Implants can be placed in infected extraction sockets after thorough socket debridement. For aesthetics, WKG should be considered when performing immediate implant placement in infected sites.

An immediate peri-implantitis induction model to study regenerative peri-implantitis treatments.

OBJECTIVES: The aim of this study was to evaluate the validity of the immediate peri-implantitis model to test regenerative therapies in peri-implantitis defects. MATERIAL AND METHODS: In an immediate peri-implantitis model in beagles, the mandibular third premolars were extracted, and dental implants were immediately placed in the distal extraction sockets. Without a healing period, experimental peri-implantitis was induced by ligature placement for 3 months. In the conventional peri-implantitis model, dental implants were placed in the healed mandibular fourth premolar region and were submerged for osseointegration. After 3 months of healing, peri-implantitis induction was performed for another 3 months. After peri-implantitis defects were formed in both models, regenerative therapy was performed in both models. RESULTS: After 3 months in the immediate model and 9 months in the conventional model, similarly shaped horizontal bone defects (wide and craterlike) were observed. However, buccal bone defects were deeply formed in the immediate model compared with the conventional model (6.02 ± 1.20 and 4.34 ± 0.86 mm, respectively; P = 0.009), but the amounts of bone regeneration were not significantly different between the models (P = 0.107). On the lingual side, re-osseointegration was significantly greater in the conventional model than in the immediate model (0.72 ± 0.50 and 1.77 ± 0.87 mm, respectively; P = 0.009), although lingual bone defects were not significantly different between the models (P = 0.248). CONCLUSIONS: Although the immediate peri-implantitis model is challenging for regeneration, it may be able to replace the conventional model to study regenerative peri-implantitis treatment due to its short experimental time and similar defect configuration.

3D Printed, Microgroove Pattern-Driven Generation of Oriented Ligamentous Architectures.

Specific orientations of regenerated ligaments are crucially required for mechanoresponsive properties and various biomechanical adaptations, which are the key interplay to support mineralized tissues. Although various 2D platforms or 3D printing systems can guide cellular activities or aligned organizations, it remains a challenge to develop ligament-guided, 3D architectures with the angular controllability for parallel, oblique or perpendicular orientations of cells required for biomechanical support of organs. Here, we show the use of scaffold design by additive manufacturing for specific topographies or angulated microgroove patterns to control cell orientations such as parallel (0°), oblique (45°) and perpendicular (90°) angulations. These results demonstrate that ligament cells displayed highly predictable and controllable orientations along microgroove patterns on 3D biopolymeric scaffolds. Our findings demonstrate that 3D printed topographical approaches can regulate spatiotemporal cell organizations that offer strong potential for adaptation to complex tissue defects to regenerate ligament-bone complexes.

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.

Decontamination methods using a dental water jet and dental floss for microthreaded implant fixtures in regenerative periimplantitis treatment.

OBJECTIVE: This study evaluated decontamination methods using a dental water jet and dental floss on microthreaded implants for regenerative periimplantitis therapy. MATERIALS AND METHODS: In 6 beagle dogs, experimental periimplantitis was induced, and decontamination procedures, including manual saline irrigation (control group), saline irrigation using a dental water jet (group 1) and saline irrigation using a dental water jet with dental flossing (group 2), were performed. After in situ decontamination procedures, some of the implant fixtures (n = 4 per group) were retrieved for analysis by SEM, whereas other fixtures (n = 4 per group) underwent regenerative therapy. After 3 months of healing, the animals were killed. RESULTS: The SEM examination indicated that decontamination of the implant surfaces was the most effective in group 2, with no changes in implant surface morphology. The histological examination also revealed that group 2 achieved significantly greater amounts of newly formed bone (6.75 ± 2.19 mm; P = 0.018), reosseointegration (1.88 ± 1.79 mm; P = 0.038), and vertical bone fill (26.69 ± 18.42%; P = 0.039). CONCLUSION: Decontamination using a dental water jet and dental floss on microthreaded implants showed positive mechanical debridement effects and positive bone regeneration effects.

A randomized controlled trial of immediate implant placement comparing hydroxyapatite nano-coated and uncoated sandblasted/acid-etched implants using a digital surgical guide.

PURPOSE: This study evaluated the implant stability, volumetric changes, and patient-reported outcome measures (PROMs) of hydroxyapatite (HA) nano-coated sandblasted/acid-etched (SLA) implants compared to uncoated SLA implants. METHODS: Forty patients were recruited and randomly allocated to HA nano-coated SLA group (test, n = 20) and uncoated SLA group (control, n = 20) using single-blinded/block randomization. Implants were immediately placed in maxillary posterior region using a digital surgical guide. Insertion torque and implant stability quotient (ISQ) were measured at implant surgery and 1, 2, 3, and 4 months postoperatively. Intraoral scans, PROMs and soft tissue inflammation data were collected, and multivariable linear regression analysis of ISQ was performed. RESULTS: In total, 48 implants (test; n = 24, control; n = 24) in 37 patients (test; n = 19, control; n = 18) were analyzed. Despite no significant between-group difference at surgery, the test group showed higher ISQ values than the control group at 2 (76.53 ± 4.17 vs. 71.32 ± 4.79, p < 0.01), 3 (77.45 ± 4.41 vs. 73.85 ± 4.69, p < 0.05), and 4 months (79.08 ± 2.96 vs. 73.43 ± 3.52, p < 0.0001) postoperatively. There were no significant differences in linear and volumetric changes, PROMs, and soft tissue inflammation analysis between two groups. The ISQ at implant surgery was influenced by age and diabetes mellitus (DM) at the implant level and DM and predicted total bone-to-implant contact area at the patient level. CONCLUSION: HA nano-coated SLA implants promoted favorable immediate implants stability during early osseointegration phase compared to uncoated SLA implants, but displayed similar dimensional changes, PROMs, and soft tissue inflammation outcomes. TRIAL REGISTRATION: Clinical Research Information Service (CRIS), KCT0006364. Registered 21 July 2021, https://cris.nih.go.kr/cris/search/detailSearch.do?seq=24221&search_page=L .

Adjunctive effect of 470-nm and 630-nm light-emitting diode irradiation in experimental periodontitis treatment: a preclinical study.

PURPOSE: This study investigated the adjunctive effect of light-emitting diodes (LEDs) in the treatment of experimental periodontitis. METHODS: Experimental periodontitis was induced by placing ligatures around the mandibular second, third, and fourth premolars of 6 beagles for 3 months. After ligature removal, periodontitis progressed spontaneously for 2 months. The animals' hemimandibles were allocated among the following 3 groups: 1) no treatment (control), 2) scaling and root planing (SRP), and 3) SRP with LED irradiation at 470-nm and 630-nm wavelengths (SRP/LED). The probing pocket depth (PPD) and gingival recession (GR) were measured at baseline, 6 weeks, and 12 weeks. The clinical attachment level (CAL) was calculated. After 12 weeks, histological and histomorphometric assessments were performed. The distances from the gingival margin to the apical extent of the junctional epithelium (E) and to the connective tissue (CT) attachment were measured, as was the total length of soft tissue (ST). RESULTS: PPD and CAL increased at 12 weeks compared with baseline in the control group (6.31±0.43 mm to 6.93±0.50 mm, and 6.46±0.60 mm to 7.61±0.78 mm, respectively). PPD and CAL decreased at 12 weeks compared with baseline in the SRP group (6.01±0.59 to 4.81±0.65 mm, and 6.51±0.98 to 5.39±0.93 mm, respectively). PPD and CAL decreased at 12 weeks compared with baseline in the SRP/LED group (6.03±0.39 to 4.46±0.47 mm, and 6.11±0.47 to 4.78±0.57 mm, respectively). The E/ST and CT/ST ratios significantly differed among the 3 groups (P<0.05). The clinical parameters and histologic findings demonstrated that 470-nm and 630-nm wavelength LED irradiation accompanying SRP could improve treatment results. CONCLUSIONS: Within the study limitations, 470 nm and 630 nm wavelength LED irradiation might provide additional benefits for periodontitis treatment.

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.

Preclinical comparison study of experimental peri-implantitis between alveolar ridge preservation and spontaneous healing sites in infected and noninfected tooth: a randomized blinded in vivo study.

BACKGROUND: This study compared the progression of experimental peri-implantitis between alveolar ridge preservation (ARP) and spontaneous healing (SH) sites in infected (IT) and noninfected tooth (NIT). METHODS: Bilateral mandibular third or fourth premolars of six beagle dogs were randomly assigned to IT and NIT groups. Before extraction, chronic dehiscence defects were created at the mesial root of mid-buccal area in IT group. Four weeks later, the mesial roots of the third and fourth premolars were extracted in all groups.ARP procedure was randomly conducted on one side of the extraction sockets using collagenated bovine bone substitutes and resorbable collagen membrane, and contralateral side was allowded spontaneous healing. After 12 weeks of healing, bone-level implants (ϕ 3.6 × 8.0 mm) were placed at the extraction sockets. Three months of ligature induced peri-implantitis and three months of spontaneous progression were allowed, with radiographs taken at each phase. Biopsies were retrieved at the implant site for histomorphometric, immunohistochemical, and polarized light-microscopic analyses. RESULTS: Radiography demonstrated that the changes in the marginal bone level during the spontaneous progression period showed no significant differences between ARP and SH sites. Only small and/or nonsignificant differences in the progression of peri-implantitis were observed between ARP and SH sites in histomorphometric, immunohistochemical, and polarized light microscopic analyses. Additionally, the IT and NIT groups exhibited similar outcomes for most parameters. CONCLUSION: ARP with xenogenic bone substitutes might provide similarly robust results as SH sites regarding the progression of experimental peri-implantitis, irrespective of the infected or noninfected nature of the site before tooth extraction.

Clinical evaluation of implants placed within or beyond the boundaries of the alveolar ridge preservation: a retrospective case series with 10 weeks of observations in 28 patients.

PURPOSE: This study investigated the effect of implant vertical positioning within alveolar ridge preservation (ARP) sites on implant stability quotient (ISQ) values, which were measured 10 weeks post-implantation. METHODS: Patients who underwent ARP using collagenized deproteinized bovine bone mineral, followed by implant placement in the posterior area, were divided into 2 groups: the within-ARP group and the beyond-ARP group. In the within-ARP group, osteotomy and implant placement occurred within the ARP boundary. In contrast, in the beyond-ARP group, these procedures were performed beyond the ARP boundary, incorporating 3 mm of pristine bone at the implant's apex. Bone quality was assessed by tactile sense, and both insertion torque during implant surgery and ISQ values at 10 weeks post-implant surgery were measured. Multiple linear regression analysis and Pearson correlation analysis were used to explore the relationship between insertion torque and ISQ values. RESULTS: In total, 30 ARP sites in 28 patients were analyzed. There was no significant difference in bone quality, as determined by tactile sense, between the within-ARP and beyond-ARP groups. At the time of implant placement, the beyond-ARP group exhibited a higher insertion torque (33.33±13.39 Ncm) compared to the within-ARP group (17.08±11.17 Ncm). However, the ISQ values were similar between the 2 groups 10 weeks after implant placement. A positive correlation between insertion torque and ISQ values was confirmed at 10 weeks post-implant. CONCLUSIONS: The engagement of pristine bone may facilitate high insertion torque during the placement of implants in ARP sites. Nevertheless, by 10 weeks post-implantation, the ISQ values were found to be comparable, irrespective of the implant's position.