The impact of Anatomic Features of Asymptomatic Third Molars on the Pathologies of Adjacent Second Molars: A Cross-sectional Analysis.

BACKGROUND: We aimed to comprehensively examine how the anatomic characteristics of asymptomatic third molars (As-M3s) affect distal pathologies of adjacent second molars (Ad-M2s). MATERIALS AND METHODS: Patients with at least 1 quadrant having intact As-M3s and first and second molars were enrolled. Distal pathologies of Ad-M2s, including caries, pocket depth of 4 mm or more (PD4+), and alveolar bone loss of 3 mm or more (ABL3+), were analysed based on As-M3 status (absent/impacted/nonimpacted). Especially within nonimpacted M3s (N-M3s), the effects of regions (maxillary vs mandibular) and dental intervals (narrow vs wide) on Ad-M2 pathologies were further compared. RESULTS: A total of 248 patients with their 805 quadrants were finally included in this cross-sectional study. The impacted and nonimpacted As-M3s elevated the risk of any distal pathology (caries, PD4+, or ABL3+) of Ad-M2s vs M3 absence with odds ratios (ORs) of 8.33 and 3.27, respectively. Within N-M3s, mandibular regions increased the odds of PD4+ (OR, 1.96); wide dental intervals increased the odds of ABL3+ (OR, 3.01). However, maxillary regions and narrow dental intervals contributed to more severe bone loss in Ad-M2s with ABL3+. CONCLUSIONS: The presence of As-M3 is a risk factor for Ad-M2 pathologies irrespective of impaction status. Within N-M3s, Ad-M2 pathologies are significantly influenced by anatomic characteristics such as regions and dental intervals.

How the Loss of Second Molars Corresponds with the Presence of Adjacent Third Molars in Chinese Adults: A Retrospective Study.

Third molars (M3s) can increase the pathological risks of neighboring second molars (M2s). However, whether the M3 presence affects M2 loss remains unknown. This retrospective study aimed to reveal the reasons for M2 loss and how M2 loss relates to neighboring M3s. The medical records and radiographic images of patients with removed M2(s) were reviewed to analyze why the teeth were extracted and if those reasons were related to adjacent M3s. Ultimately, 800 patients with 908 removed M2s were included. In the included quadrants, 526 quadrants with M3s were termed the M3 (+) group, and the other 382 quadrants without M3s were termed the M3 (−) group. The average age of patients in the M3 (+) group was 52.4 ± 14.8 years and that of the M3 (−) group was 56.7 ± 14.9 years, and the difference between the two groups was statistically significant (p < 0.001). Of the 908 M2s, 433 (47.7%) were removed due to caries and sequelae and 300 (33.0%) were removed due to periodontal diseases. Meanwhile, 14.4% of the M2s with adjacent M3s were removed due to distal caries and periodontitis, which were closely related to the neighboring M3s; this percentage was much lower when M3 were absent (1.8%). Additionally, 42.2% of M3s were removed simultaneously with neighboring M2s. The presence of M3s, regardless of impaction status, was associated with an earlier loss of their neighboring M2s.

Metformin combats high glucose-induced damage to the osteogenic differentiation of human periodontal ligament stem cells via inhibition of the NPR3-mediated MAPK pathway.

BACKGROUND: High glucose-induced damage to the osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) has long been a challenge to periodontal regeneration for diabetic individuals. Metformin is an anti-hyperglycemic drug that exhibits abundant biological activities associated with cell metabolism and downstream tissue regeneration. However, how metformin combats damage to PDLSC osteogenic differentiation under high glucose and the underlying mechanisms remain unknown. METHODS: Osteogenic differentiation of PDLSCs was assessed by alkaline phosphatase (ALP) staining, ALP activity, Alizarin Red staining and quantitative assay, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis. RNA-seq analysis was performed to screen target genes of metformin, and the effects of target genes were confirmed using lentivirus transfection. Western blot analysis was also used to detect the protein level of underlying signaling pathways. RESULTS: We found that osteogenic differentiation of PDLSCs under high glucose was decreased, and metformin addition enhanced this capacity of differentiation. Furthermore, the results of RNA-seq analysis showed that natriuretic peptide receptor 3 (NPR3) was upregulated in PDLSCs under high glucose and downregulated after metformin addition. When the underlying pathways involved were investigated, we found that upregulation of NPR3 can compromise the metformin-enhanced PDLSC osteogenic differentiation and activate the MAPK pathway (especially the p38 MAPK and Erk1/2 pathway), and that inhibition of the NPR3-mediated p38 MAPK or Erk1/2 pathway enhanced the osteogenic differentiation of PDLSCs under high glucose. CONCLUSIONS: The present study suggests that metformin may enhance the osteogenic differentiation of PDLSCs under high glucose via downregulation of NPR3 and inhibition of its downstream MAPK pathway. This is the first report identifying the involvement of NPR3-mediated MAPK pathway in the metformin-enhanced osteogenic differentiation, indicating that NPR3 antagonists, such as metformin, may be feasible therapeutics for periodontal tissue regeneration in diabetic individuals.

The Effect of Nonaugmentative Approaches in the Surgical Treatment of Peri-implantitis: A Systematic Review and Network Meta-analysis.

PURPOSE: This systematic review and Bayesian network meta-analysis (NMA) were performed to compare the clinical effects of nonaugmentative adjunctive approaches in the surgical treatment of peri-implantitis. MATERIALS AND METHODS: A systematic search of six electronic databases was performed up to June 20, 2020. Additional relevant literature was identified through gray literature and hand searches. Randomized controlled trials (RCTs) of surgical treatment of periimplantitis with nonaugmentative adjunctive approaches were included. Probing depth (PD) changes, marginal bone level (MBL) changes, and treatment success rates were extracted and assessed. Pairwise meta-analysis and Bayesian NMA were performed. This review was registered at PROSPERO (CRD42020191113). RESULTS: The search yielded 7,419 articles, of which 10 studies with 11 articles were included in the quantitative analysis. In the NMA of mechanical approaches and photodynamic therapy (PDT), compared with hand curettes, implantoplasty provided significant additional PD improvement at the 6-month follow-up evaluation (mean difference [MD]: 1.29; 95% confidence interval [CI]: 0.17, 2.38) and 12-month follow-up evaluation (MD: 1.39; 95% CI: 0.91, 1.74). In the NMA of antiseptics and systemic antibiotics, adjunctive use of antiseptics and/or systemic antibiotics did not provide significant improvement in PD or MBL. In the NMA of all adjunctive approaches, no significant differences were found in PD improvements. CONCLUSION: Within the limitations of this systematic review and NMA, implantoplasty is more effective than hand curettes in improving PD in the surgical treatment of peri-implantitis. Chemical antiseptics or systemic antibiotics have a limited effect on improving PD and MBL.

Comprehensive Transcriptome Analysis of mRNA Expression Patterns Associated With Enhanced Biological Functions in Periodontal Ligament Stem Cells Subjected to Short-Term Hypoxia Pretreatment.

Short-term hypoxia pretreatment significantly enhances periodontal ligament stem cell (PDLSC)-based periodontal tissue regeneration by improving various cellular biological functions, but the underlying mechanisms remain unclear. In this study, based on RNA sequencing (RNA-seq), we comprehensively analyzed the possible regulatory mechanisms of the short-term hypoxic effects on the biological functions of healthy and inflammatory PDLSCs. A total of 134 and 164 differentially expressed genes (DEGs) were identified under healthy and inflammatory conditions, respectively. Functional enrichment analyses indicated that DEGs under both conditions share certain biological processes and pathways, including metabolic processes, developmental processes, reproductive processes, localization, immune system processes and the HIF-1 signaling pathway. The DEGs identified under inflammatory conditions were more significantly enriched in cell cycle-related processes and immune-related pathways, while DEGs identified under healthy condition were more significantly enriched in the TGF-ß signaling pathway. A protein-protein interaction network analysis of the 59 DEGs in both conditions was performed, and 15 hub genes were identified. These hub genes were mainly involved in glycolysis, the cellular response to hypoxia, cell differentiation, and immune system processes. In addition, we found that hypoxia induced significant differential expression of genes associated with proliferation, differentiation, migration, apoptosis and immunoregulation under both healthy and inflammatory conditions. This study provides comprehensive insights into the effects of short-term hypoxia on the biological functions of PDLSCs and suggests a potentially feasible strategy for improving the clinical effectiveness of cell-based periodontal tissue engineering.

Prophylactic Antibiotics Can Prevent Early Implant Failure, but Postoperative Antibiotics May Not Be Beneficial for Dental Implant Placement.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Antibiotic prophylaxis in dental implant placement: which is the best protocol? A systematic review and network meta-analysis. Romandini M, De Tullio I, Congedi F, Kalemaj Z, D'Ambrosio M, Laforí A, Quaranta C, Buti J, Perfetti G. J Clin Periodontol 2019; 46(3):382-95. SOURCE OF FUNDING: No external funding. TYPE OF STUDY/DESIGN: Systematic review and network meta-analysis.

Effect of Asymptomatic Visible Third Molars on Periodontal Health of Adjacent Second Molars: A Cross-Sectional Study.

PURPOSE: Evidence that asymptomatic third molars (M3s) negatively affect their adjacent second molars (A-M2s) is limited. The present study evaluated the association between visible M3s (V-M3s) of various clinical status with the periodontal pathologic features of their A-M2s. PATIENTS AND METHODS: Subjects with at least 1 quadrant having intact first and second molars, either with V-M3s and symptom free or without adjacent V-M3s, were enrolled in the present cross-sectional investigation. Periodontal parameters, including plaque index (PLI), bleeding on probing (BOP), probing pocket depth (PPD), and at least 1 site with a PPD of 5 mm or more (PPD5+), obtained from M2s were analyzed according to the presence or absence of V-M3s or the status of the M3s. The χ2 test or t test was used to compare the mean PLI, PPD, BOP percentage, and PPD5+ percentage. The association of PPD5+ with V-M3 status was assessed using a multivariable logistic regression model (quadrant-based analysis), and variances were adjusted for clustered observations within subjects. RESULTS: In total, 572 subjects were enrolled in the study, and 423 had at least 1 V-M3. At the in-quadrant level, the presence of a V-M3 significantly increased M2 pathologic parameters, including PLI, PPD, BOP, and PPD5+. When analyzed using a multivariate logistic regression model, impacted M3s and normally erupted M3s significantly elevated the risk of PPD5+ on their A-M2s (odds ratio 3.20 and 1.67, respectively). Other factors associated with an increased odds of PPD5+ were mandibular region and older age. Finally, the patient-matched comparison showed that the percentage of BOP and PPD5+ on M2s increased when V-M3s were present. CONCLUSIONS: Irrespective of their status, the presence of V-M3s is a risk factor for the development of periodontal pathologic features in their A-M2s. Although the prophylactic removal of asymptomatic V-M3s remains controversial, medical decisions should be made as early as possible, because, ideally, extraction should be performed before symptom onset.

Nonimpacted Third Molars Affect the Periodontal Status of Adjacent Teeth: A Cross-Sectional Study.

PURPOSE: Most previous studies of the effect of third molars (M3s) on the health of adjacent second molars (A-M2s) have focused on impacted M3s (I-M3s). The purpose of this study was to investigate whether nonimpacted M3 (N-M3s) could affect the periodontal status of A-M2s. PATIENTS AND METHODS: In this cross-sectional study, patients (≥18 years) who had at least 1 quadrant with intact first and second molars and a nonimpacted or absent M3 were enrolled in this study. The periodontal measurements of M2 (6 sites) in the examined quadrants included the gingival index (GI), plaque index (PLI), probing pocket depth (PPD), clinical attachment level (CAL), gingival recession, and bleeding on probing (BOP). The mean GI, PLI, PPD, CAL, and BOP proportion and the proportion with at least 1 site with a PPD of at least 5 mm (PPD5+) were compared using the t test or χ2 test. The association of PPD5+ (percentage) or BOP (percentage) with the presence of N-M3s was assessed using a 2-level logistic regression model (quadrant-based analysis). RESULTS: One hundred thirty-five patients (43.7% men; 40.6 ± 11.5 yr old) were enrolled in this study. Patients who had at least 1 quadrant with 3 intact molars and an N-M3 were enrolled in group A (105 patients), and patients who had at least 1 quadrant with intact first and second molars without an M3 were enrolled in group B (30 patients). The periodontal parameters (ie, GI, PLI, PPD, CAL, BOP, and PPD5+) were markedly greater in group A. When other factors associated with periodontal disease were controlled, N-M3s were associated with the PPD5+ (odds ratio = 6.7) and BOP (odds ratio = 4.0) of the A-M2s. Other factors positively associated with A-M2 PPD5+ were location on the mandible, age older than 35 years, and smoking. CONCLUSIONS: The presence of N-M3s is a potential risk factor for the development of periodontitis in A-M2s.

Influence of Non-Impacted Third Molars on Pathologies of Adjacent Second Molars: A Retrospective Study.

BACKGROUND: Although removal of impacted third molars (I-M3s) is common in dental clinics, the decision to retain or remove asymptomatic non-impacted third molars (N-M3s) presents a significant challenge. This study investigates influence of N-M3s on pathologies of adjacent second molars (A-M2s). METHODS: Clinical status of M3s was evaluated, and presence of distal caries, external root resorption (ERR), and alveolar bone loss (ABL) of A-M2s was assessed by orthopantomograms (OPGs). Prevalence of A-M2 pathologies was evaluated and association between N-M3s and pathologies of A-M2s was analyzed by multivariate logistic regression. Significance level was set at 0.05. RESULTS: OPGs from 1,958 patients were included in the present study. Among these patients, 45.1% presented with at least one N-M3, and 44.2% of retained M3s were non-impacted. Where N-M3s were present, prevalence of distal caries, ERR, and ABL of A-M2s was 10.0%, 0.8%, and 40.4%, respectively. Although N-M3s did not increase the odds of caries or ERR of A-M2s, presence of N-M3s was associated with 1.77 times higher likelihood of ABL from A-M2s when data were adjusted for age and sex. CONCLUSIONS: Presence of N-M3s, even if they are asymptomatic, represents an important risk factor for periodontal health of A-M2s. This finding should be considered during clinical decision making regarding retention or extraction of N-M3s, especially when these teeth are non-functional or when their removal will not affect overall occlusal function.