Evaluation of Retentive Strength of 50 Endodontically-Treated Single-Rooted Mandibular Second Premolars Restored with Cast Post Cores Using 5 Common Luting (Cement) Agents.

BACKGROUND A luting agent is a dental cement used to secure a dental restoration. This study aimed to evaluate retentive strength of 50 endodontically-treated single-rooted mandibular second premolars (extracted) restored using 5 common luting (cement) agents. MATERIAL AND METHODS Fifty single-rooted mandibular second premolars with adequate root length and uniform size/shape were decoronated. After completing endodontic biomechanical preparation and obturation, root canals of all specimens were prepared to receive a cast post core. Depending upon cementation type, CPC specimens were divided in 5 groups (10 each) (Gp): Zinc phosphate (Gp ZP), polycarboxylate (Gp PC), glass ionomer (Gp GI), resin-modified glass ionomer (Gp RGI), and resin cement (Gp RC). Retentive strength was determined using the adhesive failure pull-out test. Mean/standard deviations were calculated for tensile forces (in kilograms) and differences were determined using analysis of variance (ANOVA). Multiple comparison was performed using the t test. A P value of ≤0.05 indicated a statistically significant difference. RESULTS The order of mean tensile strength from higher to lower was Gp RC (21.46) >Gp RGI (18.17) >Gp GI (16.07) >Gp ZP (15.33) >Gp PC (13.63). Differences in retentive strengths between the cements were significant (P≤0.05). Multiple-group comparisons showed that except for Gp ZP and Gp GI, all groups differed significantly from each other. CONCLUSIONS All investigated cements provided optimal retentive strengths, with wide differences between them. Resin cements should be used when CPC removal is not anticipated, while polycarboxylate or zinc phosphate should be used if CPC removal is anticipated.

Chronic metabolic and induced stress impacts mesenchymal stromal cell differentiation and modulation of dental origin in-vitro.

The impact of induced (smoking) and metabolic stress (diabetes) on dental stem cells with respect to pre-impact consideration on differentiation and bone formation were investigated. The progenitor stem cells isolated from dental pulp, follicle and gingival tissues were phenotyped and subjected to nicotine and high glucose stress mimicking the smoking and diabetic condition in-vitro. The results showed that the cellular viability post treatment with 100 µM nicotine and 10uM glucose was about 86% to 89% respectively in all the three cell types while about 73% in combined nicotine and glucose treatment. No variation in the expression of pro-inflammatory TNF-α, IL-1ß and IL-12 in all the three cell types were noticed. The observed viability in nicotine treated cells were due to elevated IL-6, IL-10 while in glucose was due to brain derived neurotropic factor (BDNF). Higher expression of IL-4, IL-6, IL-10, TGF-ß and heme oxygenase -1 (HO-1) were found high in both stressors treated cells. Differentiation and mineralization markers Alkaline phosphatase (ALP), Collagenase I (COL1), Osteocalcin, Runt related transcription factor 2 (RUNX2), Osteopontin and Bone sialoprotein were expressed in the dental pulp stem cells (DPSCs) and gingival mesenchymal stem cells (GMSCs) at varying levels post nicotine or glucose treatment while not significantly observed in dental follicular stem cells (DFSCs). Therefore, it is evident that the stem cells of varied dental origin responded to the stress are more or less uniform with physiological delay in differentiation into osteoblast. It is evident from the study that, the metabolic or induced stress subverts the process of regenerative healing by mesenchymal stromal cells with their anatomical niche.

Ultrastructural and physicochemical characterization of pH receptive chlorhexidine-loaded poly-L-glycolic acid-modified orthodontic adhesive.

This study aims to evaluate the feasibility of chlorhexidine (CHX)-loaded poly-L-glycolic acid (PLGA) nanoparticles as a modifier of a commercial orthodontic adhesive via the assessment of physicochemical, biological, and mechanical properties at tooth-bracket interface. CHX-loaded PLGA nanoparticles were synthesized using double emulsion-solvent evaporation method and characterized using transmission electron microscopy and Raman analysis. CHX-loaded PLGA nanoparticles in Transbond XT orthodontic adhesive were prepared using two different concentrations of the CHX (25 and 50%) and characterized for degree of conversion (DC), antimicrobial, and cytotoxicity testing. Bonded specimens were tested for shear bond strength (SBS) and adhesive remnant index (ARI) at tooth-bracket interface. The synthesized PLGA nanoparticles averaged between 60 and 80 nm in size. After loading CHX inside PLGA nanoparticles, the morphology of the PLGA nanoparticles was considerably changed. Orthodontic bracket bonded with 25% CHX-loaded PLGA-modified adhesive demonstrated DC scores similar to control group. Both 25 and 50% CHX-loaded PLGA-modified adhesive specimens showed higher antibacterial activity against S. mutans compared to control group. The least mean SBS values were exhibited by 50% CHX-loaded PLGA-modified adhesive samples, while a statistically significant difference was observed in the mean ARI values among all study groups at all-time points (p = .018). This study indicates that the addition of CHX-loaded PLGA nanoparticles in Transbond XT achieved stable bonds with enhanced antimicrobial and mechanical properties.

Effect of ultrasonic scaling with adjunctive photodynamic therapy on the treatment of gingival inflammation among diabetic patients undergoing fixed orthodontic treatment.

BACKGROUND: The aim of the present clinical trial was to evaluate the effect of methylene blue-mediated antimicrobial photodynamic therapy (aPDT) on the gingival and immunological parameters in diabetic adolescent patients undergoing fixed orthodontic treatment. METHODS: The selected 40 participants were randomized equally into two groups; Group I (ultrasonic scaling + oral hygiene instructions) and Group II (ultrasonic scaling/oral hygiene instructions + aPDT). Serum HbA1c levels was assessed for all the participants at chairside. Plaque index (Pi), and bleeding on probing (BOP) were analyzed. Moreover, the assessment of crevicular fluid matrix metalloproteinase 8 (MMP-8) and macrophage inflammatory protein 1 alpha (MIP-1α) was performed using enzyme-linked immunosorbent assay technique. All measurements were recorded at baseline, 6 weeks, and 12 weeks follow-up periods, respectively. Intergroup comparisons for p-value were computed using Mann-Whitney test and Wilcoxon singed ranks test to compute p-value for intra-group comparisons. Stepwise logistic regression analysis was used to identify explanatory variables for reduction in plaque scores and bleeding on probing, after controlling for the effects of other covariates. Odds ratios and 95% confidence intervals were used to assess the direction and strength for associations. Significance level was set at 5% for all analyses. RESULTS: All 40 individuals completed the clinical trial. There was a statistically significant reduction in Pi and BOP in both Group I and Group II from baseline to 12 weeks of follow up (P<0.05). However, there was slight reduction in the plaque scores in Group-II as compared to Group-I at 12 weeks visit (P<0.05). There was also a statistically significant difference for BOP when Group-I was compared with Group-II on 12 weeks follow up assessment (P<0.05). HbA1c assessment indicated no statistically significant difference either within or between groups at any time point (P>0.05). Both MMP-8 and MIP-1α reported a significant decrease for both Groups I and II at 6 weeks and 12 weeks follow-up periods in comparison to baseline (P<0.05). Inter-group comparison indicated a statistically significant difference noted at both 6 weeks follow up that was maintained at 12 weeks follow up (P<0.05). The logistic regression analysis revealed that even after controlling the mean BMI as a predictor, the change of biomarker levels along with the improvement in plaque scores and bleeding on probing was not significant (p> 0.05). CONCLUSION: aPDT significantly improved bleeding on probing and proinflammatory biomarkers among diabetic adolescent patients undergoing fixed orthodontic therapy.

Impact of riboflavin mediated photodynamic disinfection around fixed orthodontic system infected with oral bacteria.

PURPOSE: The aim of this laboratory study was to investigate the amount of bacterial destruction through riboflavin mediated photodynamic therapy (PDT) around fixed orthodontic devices by using the two strains of bacteria Streptococcus mutans and Streptococcus sanguinis. MATERIALS AND METHODS: A total of 80 metallic brackets were divided into four groups consisting of 20 brackets each. Group-I: riboflavin + LED irradiation; Group-II: riboflavin alone; Group-III: immersion in 0.2 % chlorhexidine gluconate solution and Group-IV: not submitted to any treatment. All metallic brackets were immersed in the standard bacterial solutions and incubated at 48 h. All samples were subjected to MTT assay for microbial cell viability testing after treatment. After 24 h of incubation, biofilms adhered on the mesh of metallic brackets after treatment were assessed by confocal laser microscopy. The total CFU/mL was estimated, and the results were log-transformed (log10) and analyzed using one-way analysis of variance and Tukey-Kramer test. P-value was set to <0.05 that indicated statistical significance. RESULTS: The samples from group-IV showed the highest amount of relative biofilm viability compared to any other group while group-I (PDT) showed the least viability of the two bacterial strains studied (p < 0.05). Group-I showed no significant difference when compared with group-III (chlorhexidine) (p > 0.05). The biofilms on the samples from group-II and group-IV were largely viable indicating thick green staining across the mesh of the brackets. Among the group-III samples, there were predominantly dead cells as compared to the live cell staining. A considerable amount of red staining was observed with noticeable less green staining in group-I samples. CONCLUSION: This laboratory investigation revealed that riboflavin mediated PDT significantly reduced the amounts of S. mutans and S. sanguinis around the orthodontic brackets.

Does preoperative dental anxiety play a role in postoperative pain perception after third molar surgery?

Background: Surgical removal of the impacted third molar is associated with inflammatory morbidities which include swelling, trismus, and pain. Pain is the most common postsurgical morbidity associated with third molar surgery. It remains an important factor in patients' perception of recovery after third molar surgery with dental anxiety reported to exert influence on its threshold. Objective: The aim of the study was to determine if preoperative dental anxiety has any significant role on postoperative pain perception after third molar surgery. Materials and Methods: This was a cohort study involving sixty consecutive adult patients requiring extraction of impacted mandibular third molars under local anesthesia. Modified Dental Anxiety Scale Questionnaire was administered to each participant in the waiting area before the surgery. The visual analog scale was also given to each participant to be completed once daily at approximately the same time as the surgery time until day 7 after the surgery. Data collected were analyzed using SPSS version 23. Results: Sixty participants who consented to third molar surgery took part in this study. Five participants were lost to follow-up. There were slightly more males (50.9%) than females (49.1%). Nineteen participants in this study had moderate dental anxiety (34.5%) and 6 participants (11%) had severe dental anxiety with more females having moderate-to-severe dental anxiety. The correlation between pain perception at different days and dental anxiety was not significant (P > 0.05). Conclusion: Preoperative dental anxiety may not significantly influence pain perception after third molar surgery.

RésuméContexte: L'extraction chirurgicale de la troisième molaire incluse est souvent accompagnée d'un gonflement, d'une difficulté à ouvrir la bouche et de douleurs. La douleur est la morbidité post-chirurgicale la plus courante associée à la chirurgie de la troisième molaire. C'est un facteur important qui détermine la façon dont les patients perçoivent la guérison après une chirurgie de la troisième molaire. Il est rapporté que l'anxiété dentaire a une influence sur le seuil de douleur des patients. Objectif: Pour déterminer si l'anxiété dentaire préopératoire a un rôle significatif sur la perception de la douleur postopératoire après une chirurgie de la troisième molaire. Méthodes: Soixante patients adultes nécessitant l'extraction des troisièmes molaires incluses sous anesthésie locale ont été inclus dans cette étude de recherche. Un Modified Dental Anxiety Scale Questionnaire a été administré à chaque participant dans la salle d'attente avant la chirurgie. Le Visual Analogue Scale (VAS) a également été donnée à chaque patient à compléter une fois par jour à peu près au même moment que l'heure de la chirurgie jusqu'au jour 7 après la chirurgie. Les données obtenues ont été analysées à l'aide de la version 23 de SPSS. Résultats: Soixante patients ayant consenti à une chirurgie de la troisième molaire ont participé à cette étude. Cinq patients ont été perdus de vue. Il y avait un peu plus d'hommes (50,9%) que de femmes (49,1%). Dix-neuf patients avaient une anxiété dentaire modérée (34,5%) et 6 (11%) une anxiété dentaire sévère, un plus grand nombre de femmes ayant une anxiété dentaire modérée à sévère. La corrélation entre la perception de la douleur à différents jours et l'anxiété dentaire n'était pas significative (P> 0,05). Conclusion: L'anxiété dentaire préopératoire peut ne pas avoir d'effet significatif sur la perception de la douleur après une chirurgie de la troisième molaire.

Characterization of the Cellular Reaction to a Collagen-Based Matrix: An In Vivo Histological and Histomorphometrical Analysis.

The permeability and inflammatory tissue reaction to Mucomaix® matrix (MM), a non- cross-linked collagen-based matrix was evaluated in both ex vivo and in vivo settings. Liquid platelet rich fibrin (PRF), a blood concentrate system, was used to assess its capacity to absorb human proteins and interact with blood cells ex vivo. In the in vivo aspect, 12 Wister rats had MM implanted subcutaneously, whereas another 12 rats (control) were sham-operated without biomaterial implantation. On days 3, 15 and 30, explantation was completed (four rats per time-point) to evaluate the tissue reactions to the matrix. Data collected were statistically analyzed using analysis of variance (ANOVA) and Tukey multiple comparisons tests (GraphPad Prism 8). The matrix absorbed the liquid PRF in the ex vivo study. Day 3 post-implantation revealed mild tissue inflammatory reaction with presence of mononuclear cells in the implantation site and on the biomaterial surface (mostly CD68-positive macrophages). The control group at this stage had more mononuclear cells than the test group. From day 15, multinucleated giant cells (MNGCs) were seen in the implantation site and the outer third of the matrix with marked increase on day 30 and spread to the matrix core. The presence of these CD68-positive MNGCs was associated with significant matrix vascularization. The matrix degraded significantly over the study period, but its core was still visible as of day 30 post-implantation. The high permeability and fast degradation properties of MM were highlighted.

PTCH-1 and MDM2 expression in ameloblastoma from a West African sub-population: implication for chemotherapeutics.

INTRODUCTION: Ameloblastoma is a slow growing, painless odontogenic swelling which can attain sizes that result in severe deformities of the craniofacial complex. It is the most commonly encountered odontogenic tumor in Nigeria. Surgical intervention is currently the method of treatment; however identification of altered molecular pathways may inform chemotherapeutic potential. The Protein Patched homolog 1 (PTCH-1) is overexpressed in ameloblastoma. Also, mutation in the MDM2 gene can reduce the tumor suppressor function of p53 and promote ameloblastoma growth. No study however has characterized the molecular profile of African cases of ameloblastoma with a view to developing chemotherapeutic alternatives. The objective was to characterize the PTCH-1 genetic profile of Ameloblastoma in Nigerian patients as a first step in investigating its potential for chemotherapeutic intervention. METHODS: Twenty-eight FFPE blocks of ameloblastoma cases from Nigerian patients were prepared for antibody processing to PTCH-1 (Polyclonal Anti-PTCH antibody ab39266) and MDM2 (Monoclonal Anti-MDM2 antibody (2A10) ab16895). Cytoplasmic brown staining was considered as positive for PTCH while nuclear staining was positive for MDM2. RESULTS: Moderate and strong expressions for PTCH in ameloblast and stellate reticulum were 78.6% and 60.7% respectively. Only 3 (10.7%) cases expressed MDM2. CONCLUSION: The importance of our study is that it supports, in theory, anti-PTCH/SHH chemotherapeutics for Nigerian ameloblastoma cases and also infers the possible additional use of anti-p53 agents.