How Does the First Molar Root Location Affect the Critical Stress Pattern in the Periodontium? A Finite Element Analysis.

Statement of the Problem: The first molar root location plays a pivotal role in neutralization of forces applied to the teeth to prevent injury. Purpose: This study aimed to assess the effect of maxillary and mandibular first molar root location on biomechanical behavior of the periodontium under vertical and oblique loadings. Materials and Method: In this three-dimensional (3D) finite element analysis (FEA), the maxillary and mandibular first molars and their periodontium were modeled. The Young's modulus and the Poisson's ratio for the enamel, dentin, dental pulp, periodontal ligament (PDL), and cortical and cancellous bones were adopted from previous studies. The changes in maximum von Misses stress (MVMS) values of each component were analyzed. Results: The MVMS values were the highest in the enamel followed by dentin, cortical bone, cancellous bone, and PDL. The maxillary and mandibular first molars with different root locations and their periodontium showed different biomechanical behaviors under the applied loads. Conclusion: An interesting finding was that the stress concentration point in the path of load degeneration changed from the cervical third in dentin to the apical third in the cancellous bone, which can greatly help in detection of susceptible areas over time.

Evaluation of Two Pain Assessment Methods (Tactile and Air blast) for Comparison the Effectiveness of Nd:YAG Laser Therapy and Non-Laser Therapy on Dentin Hyper Sensitivity Treatment: A Systematic Review and Meta-analysis.

Statement of the Problem: Dentin hypersensitivity (DH) is a common irritating condition. A precise sensitive test for its assessment can greatly aid in appropriate treatment planning. Purpose: This meta-analysis aims to compare the air blast and tactile tests for assessment of the efficacy Nd:YAG laser therapy versus non-laser treatments for DH in short-term and long-term follow-ups. Materials and Method: For this review, an electronic search of the literature was carried out in three databases by two researchers for English articles published until March 10, 2021. Pooling of the data extracted from the selected articles was performed according to the PRISMA statement by the random-effect model. The mean difference (MD) and 95% confidence interval (CI) of pain score before the treatment onset and during the follow-up period according to the visual analog scale (VAS) were calculated. The level of heterogeneity was assessed by the I2 test, and a funnel plot was drawn to assess the publication bias of the reviewed studies. Results: Of 152 articles primarily retrieved, 9 randomized clinical trials (RCTs) using the air blast test and 4 RCTs using the tactile test were subjected to quantitative synthesis. In the short-term follow-up and immediately after treatment, the air blast test showed superiority of laser therapy compared with non-laser treatments (SMD: 0.55, 95% CI: 0.05-1.04, p= 0.03). However, this difference was not significant according to the tactile test (SMD: 0.48. 95% CI: 0.01-0.96, p= 0.06). In the long-term follow-up, the difference between laser therapy and non-laser modalities was not significant according to both air blast (SMD= -0.38, 95% CI: -1.43-0.67, p= 0.48) and tactile (SMD=0.0, 95% CI: -0.38-0.38, p= 0.99) tests. Conclusion: Comparison of laser therapy and non-laser modalities in the short-term reveal-ed higher sensitivity of the air blast test due to its mechanism of action compared with the tactile test. Further studies are required to interpret the results in the long-term follow-up.

Clinical attachment loss in the use of adjunctive antimicrobial photodynamic therapy in Stages II-IV Grade C molar-incisor periodontitis: A systematic review and meta-analysis.

This systematic review and meta-analysis aimed to assess the extent of clinical attachment loss (CAL) as a clinical parameter in the efficacy of antimicrobial photodynamic therapy (aPDT) in non-surgical management of stage II-IV grade C molar-incisor pattern Periodontitis. This review protocol was conducted in accordance with PRISMA statements and is registered in PROSPERO (CRD42022321211). An electronic and manual search was conducted for relevant articles comparing the efficacy of aPDT versus scaling and root planning (SRP) alone or with amoxicillin/metronidazole (AMX/MET) published up until December 2021. The mean clinical attachment loss (CAL), probing depth (PD) reduction, and bleeding on probing (BOP) with a 95% confidence interval (CI) were pooled and compared between the two groups with CAL < and > 7 mm using a random-effect model after 3 and 6 months. To assess the heterogeneity of the findings, the I2 test was applied and Publication bias was evaluated by visual examination of the funnel plot symmetry. Analysis of 9 studies indicated a significant difference in clinical attachment gain in patients with CAL > 7 mm between the aPDT group and the SRP alone (mean difference=0.92, 95% CI=0.01-1.84, P=0.05) and SRP + AMX/MET (mean difference=0.91, 95% CI=-0.14-1.68, P=0.02) control groups. However, this difference was not significant in patients with CAL < 7 mm. Despite the limitations of the included studies, aPDT can be suggested for the improvement of clinical parameters in grade C molar-incisor pattern Periodontitis with CAL > 7 mm. However, its application in milder cases requires further investigation.

Amoxicillin/Metronidazole Dose Impact as an Adjunctive Therapy for Stage II - III Grade C Periodontitis (Aggressive Periodontitis) at 3- And 6-Month Follow-Ups: a Systematic Review and Meta-Analysis.

Objectives: This systematic review and meta-analysis study sought to review the efficacy of amoxicillin/metronidazole dose and duration time in the treatment of stage II - III grade C periodontitis (aggressive periodontitis) after current follow-up. Material and Methods: An electronic search of the literature was performed in three main databases for relevant articles published until 31th of December 2021. According to the PRISMA statement, the extracted data from selected articles were pooled. The weighted mean difference (MD) and 95% confidence interval (CI) of clinical attachment level (CAL) gain and probing depth (PD) reduction at 3 and 6 months of follow-up were calculated. The heterogeneity of the data was evaluated by the I2 test. Results: The results of six randomized clinical trials revealed significant improvement of clinical parameters in moderate and severe pockets. Prescription of 400 to 500 mg metronidazole caused significant CAL gain changes just in moderate pockets (MD = 1.82; 95% CI = 1.11 to 2.53; P < 0.05). Conclusions: Amoxicillin/metronidazole has positive short-term effects as an adjunct to scaling and root planning for treatment of stage II - III grade C periodontitis. Higher doses of metronidazole (400 to 500 mg) are required for optimal efficacy regarding clinical attachment level gain.

In Vitro Comparison of Biological Effects of Coe-Pak and Reso-Pac Periodontal Dressings.

OBJECTIVES: The purpose of the present study was to compare the cytotoxicity of Reso-Pac and Coe-Pak periodontal dressing. MATERIAL AND METHODS: According to ISO-10993-12:2012, 1-, 3- and 7-day extracts of the two periodontal dressings were prepared in cell culture medium and exposed to the two cultured cell lines. Cell viability and proliferation at 24 h and 72 h following exposure were evaluated using quantitative MTT assay. RESULTS: The results showed a significant (P < 0.05) reduction in the viability of cells exposed to the 3- and 7-day Coe-Pak extracts at 24 h and 72 h compared to the control group (no exposure to the extract). Reso-Pac extracts slightly decreased cell viability compared to the control group. Understudy materials showed greater cytotoxicity against human osteoblast-like compared to the human gingival fibroblast cells. No significant (P > 0.05) difference was found in the viability of cells exposed to undiluted (100%) one-day extract and diluted (50%) extract of both understudy materials at 24 h and 72 h after exposure. CONCLUSIONS: Based on the results, Reso-Pac periodontal dressing has less cytotoxicity than Coe-Pak.

Receptor activator of nuclear factor kappa-B gene polymorphisms in Iranian periodontitis and peri-implantitis patients.

PURPOSE: Peri-implantitis and periodontitis are inflammatory and infectious diseases of implant and tooth-supporting tissues. Recently, the role of gene polymorphisms of immune response components in the relevant pathogenesis has been investigated. The present study was the first to evaluate the relationship between two known single nucleotide polymorphisms (SNPs) of the receptor activator of nuclear factor kappa-ß (RANK) gene (rs3018362 and rs35211496) in chronic periodontitis and peri-implantitis patients in an Iranian population. METHODS: Eighty-one periodontally healthy patients, 38 patients with peri-implantitis, and 74 patients with chronic periodontitis were enrolled in this study. DNA was extracted from blood arm vein samples by using Miller's salting out technique according to the manufacturer's instructions given in the extraction kit. The concentration of DNA samples was measured using a spectrophotometer. The genetic polymorphisms of the RANK gene were evaluated using a competitive allele specific polymerase chain reaction (KBioscience allele specific PCR) technique. Differences in the frequencies of genotypes and alleles in the diseased and healthy groups were analyzed using chi-squared statistical tests (P<0.05). RESULTS: Analysis of rs35211496 revealed statistically significant differences in the expression of the TT, TC, and CC genotypes among the three groups (P=0.00). No statistically significant difference was detected in this respect between the control group and the chronic periodontitis group. The expression of the GG, GA, and AA genotypes and allele frequencies (rs3018362) showed no statistically significant difference among the three groups (P=0.21). CONCLUSIONS: The results of this study indicate that the CC genotype of the rs35211496 RANK gene polymorphism was significantly associated with peri-implantitis and may be considered a genetic determinant for peri-implantitis, but this needs to be confirmed by further studies in other populations.

IL-17 gene polymorphism is associated with chronic periodontitis and peri-implantitis in Iranian patients: a cross-sectional study.

Periodontal disease (PD) and peri-implantitis (PI) are characterized by an immune response leading to destructive inflammation. The prominent impact of genetic factors on periodontitis has been previously evaluated and IL-17 has found to play a critical role in this process. This cytokine has a controversial behavior. This study aimed at finding out whether the polymorphism of this cytokine plays a significant role in chronic periodontitis (CP) and PI or it is just a pro-inflammatory regulatory cytokine. Fresh human blood samples were obtained and three main genotypes were traced carefully. The samples were transferred into 96-well plates and sent to KBioscience Institute in the United Kingdom for genotyping the polymorphism using Competitive Allele Specific PCR (KASP) technique. SPSS version19 software and chi-square and Kruskal-Wallis tests were used for statistical differences considering p-value less than 0.05. A significant difference was detected between the three groups in terms of specific SNP studied in this experiment (P = 0.00). The CC genotype of IL17 polymorphism (rs10484879) may contribute to the pathogenesis of peri-implantitis and periodontitis. The association of IL-17 polymorphism with PI and CP is a promising finding that may help in future similar studies on other ethnicities and larger study populations.

Periodontal dressing: a review article.

The purpose of this paper was to review the commercially available periodontal dressings, their physical and chemical properties, biocompatibility and therapeutic effects. Electronic search of scientific papers from 1956 to 2012 was carried out using PubMed, Scopus and Wiley InterScience search engines using the searched terms periodontal dressing, periodontal pack. Numerous in vitro and in vivo studies have evaluated various properties of periodontal dressings. Physical and chemical properties of dressings are directly related to their dimensional changes and adhesion properties. Their biocompatibility and therapeutic effect are among the other factors evaluated in the literature. Chlorhexidine is the most commonly used antibacterial agent in studies. In general, when comparing the advantages with the disadvantages, application of periodontal dressing seems to be beneficial. Numerous factors are involved in selection of an optimal dressing such as surgeon’s intention, required time for the dressing to remain on the surgery site and its dimensional changes.