Evaluation of the chemical, physical, and biological properties of a newly developed bioceramic cement derived from cockle shells: an in vitro study.

BACKGROUND: Tricalcium silicate is the main component of commercial bioceramic cements that are widely used in endodontic treatment. Calcium carbonate, which is manufactured from limestone, is one of the substrates of tricalcium silicate. To avoid the environmental impact of mining, calcium carbonate can be obtained from biological sources, such as shelled mollusks, one of which is cockle shell. The aim of this study was to evaluate and compare the chemical, physical, and biological properties of a newly developed bioceramic cement derived from cockle shell (BioCement) with those of a commercial tricalcium silicate cement (Biodentine). METHODS: BioCement was prepared from cockle shells and rice husk ash and its chemical composition was determined by X-ray diffraction and X-ray fluorescence spectroscopy. The physical properties were evaluated following the International Organization for Standardization (ISO) 9917-1;2007 and 6876;2012. The pH was tested after 3 h to 8 weeks. The biological properties were assessed using extraction medium from BioCement and Biodentine on human dental pulp cells (hDPCs) in vitro. The 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5[(phenylamino)carbonyl]-2 H-tetrazolium hydroxide assay was used to evaluate cell cytotoxicity following ISO 10993-5;2009. Cell migration was examined using a wound healing assay. Alizarin red staining was performed to detect osteogenic differentiation. The data were tested for a normal distribution. Once confirmed, the physical properties and pH data were analyzed using the independent t-test, and the biological property data were analyzed using one way ANOVA and Tukey's multiple comparisons test at a 5% significance level. RESULTS: The main components of BioCement and Biodentine were calcium and silicon. BioCement's and Biodentine's setting time and compressive strength were not different. The radiopacity of BioCement and Biodentine was 5.00 and 3.92 mmAl, respectively (p < 0.05). BioCement's solubility was significantly higher than Biodentine. Both materials exhibited alkalinity (pH ranged from 9 to 12) and demonstrated > 90% cell viability with cell proliferation. The highest mineralization was found in the BioCement group at 7 days (p < 0.05). CONCLUSIONS: BioCement exhibited acceptable chemical and physical properties and was biocompatible to human dental pulp cells. BioCement promotes pulp cell migration and osteogenic differentiation.

Utilization of rapid antigen tests for screening SARS-CoV-2 prior to dental treatment.

Potential aerosols containing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral particles can be generated during dental treatment. Hence, patient triage is essential to prevent the spread of SARS-CoV-2 in dental clinical settings. The present study described the use of rapid antigen tests for SARS-CoV-2 screening prior to dental treatment in an academic dental clinical setting in Thailand during the pandemic. The opinions of dental personnel toward the use of rapid antigen test screening prior to dental treatment were also assessed. From August 25 to October 3, 2021, dental patients who were expected to receive aerosols generating dental procedures were requested to screen for SARS-CoV-2 using a rapid antigen test before their treatment. A total of 7,618 cases completed the screening process. The average was 212 cases per day. Only five patients (0.07%) were positive for SARS-CoV-2 in the rapid antigen screening tests. All positive cases exhibited mild symptoms. For the questionnaire study, experienced dental personnel frequently and consistently agreed with the use of the rapid antigen test for SARS-CoV-2 screening, which made them feel safer during their patient treatment. However, implementing rapid antigen tests for SARS-CoV-2 may increase the total time spent on a dental appointment. In conclusion, a rapid antigen test could detect the infected individual prior to dental treatment. However, the specificity of rapid antigen tests for SARS-CoV-2 must be taken into account for consideration as a screening process before dental treatment. The enhanced infection control protocols in dental treatment must be consistently implemented.

Procedures Used in Managing SARS-CoV-2 Infected Dental Personnel or Patients: A Case Study From a Thai Dental Hospital.

SARS-CoV-2 can transmit undetected from asymptomatic and pre-symptomatic patients in dental clinics. Triaging dental patients using temperature and questionnaire screening cannot completely exclude asymptomatic SARS-CoV-2 infected individuals. Hence, asymptomatic SARS-CoV-2 infected individuals might visit dental hospitals/clinics seeking dental treatment without knowing that they are infected and might infect others, especially in a pandemic area. Ideally, a nasopharyngeal swab for real-time polymerase chain reaction or rapid antigen screening for dental personnel and patients prior to their appointment should be done. However, the implementation of this approach is impractical in some situations. Here, we describe the procedures for dental hospitals/clinics in case of an asymptomatic SARS-CoV-2 infected individual involved in dental service/treatment and later after testing positive for SARS-CoV-2. Potential closely contacted individuals were traced and classified according to their exposure risk. The recommended course of action is to identify individuals based on their risk and take the risk-appropriate action. We also discuss the implementation of these procedures in a dental setting during the COVID-19 pandemic in our school as a case study.

Reinforcement of Simulated Immature Permanent Teeth after Mineral Trioxide Aggregate Apexification.

OBJECTIVES: The objectives of this study were to compare the fracture resistance of simulated human immature teeth that have undergone mineral trioxide aggregate (MTA) apexification and have been root-filled with fiber post, composite resin, MTA, or gutta-percha. METHODS: Fifty-six human permanent maxillary incisors were selected. Ten teeth received no treatment (intact teeth group). The root canals of 46 teeth were prepared to an internal diameter of 1.75 mm. Six teeth were used as simulated immature teeth group. The remaining teeth received MTA apexification and were divided into 4 groups: MTA, fiber post, composite resin, and gutta-percha groups. The root canals of each group were filled with each test material. All teeth were thermocycled and received cyclic loading before compression testing by an Instron universal testing machine. The load to fracture was recorded. Data were subjected to statistical analysis by using one-way analysis of variance and Tukey multiple comparison test. RESULTS: All teeth fractured at the cervical area of the root. The mean load to fracture of the intact tooth, MTA, fiber post, composite resin, gutta-percha, and the simulated immature tooth groups was 1988 N, 1921 N, 1691 N, 1623 N, 1476 N, and 962 N, respectively. Statistically, load to fracture of the simulated immature tooth group was significantly lower than in the intact tooth, MTA, fiber post, and composite resin groups but was not significantly different from the gutta-percha group. CONCLUSIONS: Within the limit of this study, after MTA apexification, intraradicular reinforcement with MTA, fiber post, or composite resin increased the fracture resistance of simulated immature teeth.

Treatment Outcomes of Apexification or Revascularization in Nonvital Immature Permanent Teeth: A Retrospective Study.

INTRODUCTION: The purposes of this retrospective study were to evaluate the clinical and radiographic outcomes of mineral trioxide aggregate apexification and revascularization in nonvital immature permanent teeth and to analyze factors influencing treatment outcome. METHODS: Forty-six cases (29 cases of apexification and 17 cases of revascularization) were recruited into this study. Patients' preoperative and postoperative information was analyzed. Treatment outcomes were categorized as a success or failure and functional retention. Further root development was assessed in terms of the percentage changes in root length and root width. RESULTS: The success rates of mineral trioxide aggregate apexification and revascularization were 80.77% and 76.47% and functional retention was 82.76% and 88.24%, respectively. Revascularization provided significantly greater percentage changes in root width (13.75%) in comparison with mineral trioxide aggregate (MTA) apexification (-3.30%). The mean percentage change of increased root length was 9.51% in the revascularization group and 8.55% in the MTA apexification group. Interestingly, revascularization showed various degrees of increased root length ranging from -4% to 58%. Fracture was the main cause of failure in MTA apexified teeth. All failed revascularized teeth presented with signs and symptoms of apical periodontitis caused by persistent infection. CONCLUSIONS: MTA apexification and revascularization provide a reliable outcome in the aspects of resolution of the disease and tooth functional retention. None of these treatments provides satisfactory predictable further root development.

Treatment Outcomes of Mineral Trioxide Aggregate Pulpotomy in Vital Permanent Teeth with Carious Pulp Exposure: The Retrospective Study.

INTRODUCTION: This study aimed to illustrate the treatment outcomes of mineral trioxide aggregate (MTA) pulpotomy in vital permanent teeth with carious pulp exposure. METHODS: MTA pulpotomy was performed in 66 vital permanent teeth with carious pulp exposure including teeth with signs and symptoms of irreversible pulpitis and the presence of periapical radiolucency. Patients were assessed for clinical and radiographic outcomes by 2 examiners. The relationship between treatment outcomes and factors was analyzed by means of univariate analysis and binary logistic regression. RESULTS: Fifty patients (a total of 55 teeth) attended the follow-up examination. The age of the patients ranged from 7-68 years old (mean = 29 years old). For the follow-up period as far as 62 months, 48 teeth showed successful outcomes (success rate = 87.3%). Teeth with clinical signs of irreversible pulpitis and the presence of periapical radiolucency could be treated successfully by MTA pulpotomy with success rates of 84% and 76%, respectively.Three of 7 failed cases required pulpectomy after MTA pulpotomy to relieve painful pulpitis. Four other failed cases were asymptomatic, and failure was detected from radiographic examination. The relationship between treatment outcomes and treatment factors could not be detected statistically. CONCLUSIONS: Teeth with carious pulp exposure can be treated successfully by MTA pulpotomy. Clinical signs of irreversible pulpitis and the presence of periapical radiolucency should not be considered as a contraindication for pulpotomy.

Vital pulp therapy in vital permanent teeth with cariously exposed pulp: a systematic review.

INTRODUCTION: This systematic review aims to illustrate the outcome of vital pulp therapy, namely direct pulp capping, partial pulpotomy, and full pulpotomy, in vital permanent teeth with cariously exposed pulp. METHODS: Electronic database MEDLINE via Ovid, PubMed, and Cochrane databases were searched. Hand searching was performed through reference lists of endodontic textbooks, endodontic-related journals, and relevant articles from electronic searching. The random effect method of weighted pooled success rate of each treatment and the 95% confidence interval were calculated by the DerSimonian-Laird method. The weighted pooled success rate of each treatment was estimated in 4 groups: >6 months-1 year, >1-2 years, >2-3 years, and >3 years. All statistics were performed by STATA version 10. The indirect comparison of success rates for 4 follow-up periods and the indirect comparison of clinical factors influencing the success rate of each treatment were performed by z test for proportion (P < .05). RESULTS: Overall, the success rate was in the range of 72.9%-99.4%. The fluctuation of the success rate of direct pulp capping was observed (>6 months-1 year, 87.5%; >1-2 years, 95.4%; >2-3 years, 87.7%; and >3 years, 72.9%). Partial pulpotomy and full pulpotomy sustained a high success rate up to more than 3 years (partial pulpotomy: >6 months-1 year, 97.6%; >1-2 years, 97.5%; >2-3 years, 97.6%; and >3 years, 99.4%; full pulpotomy: >6 months-1 year, 94%; >1-2 years, 94.9%; >2-3 years, 96.9%; and >3 years, 99.3%). CONCLUSIONS: Vital permanent teeth with cariously exposed pulp can be treated successfully with vital pulp therapy. Current best evidence provides inconclusive information regarding factors influencing treatment outcome, and this emphasizes the need for further observational studies of high quality.

Thermal stimulation causes tooth deformation: a possible alternative to the hydrodynamic theory?

OBJECTIVES: To investigate the relationship between temperature distribution and tooth structure deformation during and after localised application of thermal stimuli used during pulp vitality testing. METHODS: Strains and temperature changes within tooth structures were recorded when three different thermal stimuli, namely heated gutta percha (120-140 degrees C), carbon dioxide dry ice (-72 degrees C) and refrigerant spray (-50 degrees C), were applied to extracted bovine incisors. Each stimulus was applied for 5s on the labial enamel surface in a random order, with a 30-min interval between tests. Finite element analysis was performed on basic geometrical shapes to investigate structural deformation in relation to temperature change. RESULTS: Application of thermal stimuli to the labial enamel surface resulted in rapid development of strain at the pulpal dentine surface before any temperature change was detected at the dentino-enamel junction. The strain pattern was biphasic; heat produced an initial contraction of the pulpal surface, followed by an expansion, and the reverse pattern was found with cold stimulation. Finite element analysis confirmed that the initially pronounced thermal gradient across the enamel and dentine caused rapid flexural deformation before temperature changes reached the dentino-enamel junction. When the temperature changes reached the pulpal dentine and thus reduced the thermal gradient, the direction of the strain was reversed. CONCLUSION: These results indicate possible alternatives to the hydrodynamic theory for thermal stimuli applied to intact teeth. Mechanically induced dentine deformation may trigger nerve impulses directly, or may exert mechanically induced dentinal fluid flow that triggers nerve activity.

Effective cleaning protocols for rotary niclkel-titanium files.

Cleaning of dental instruments before sterilisation is an essential part of processing for re-use. Rotary nickel-titanium (NiTi) files as obtained from the manufacturer are mostly not sterile and require cleaning and sterilisation both before first use and for re-use. We describe here two simple, practical cleaning protocols that are effective in removing organic debris from files. Rotary NiTi files can be safely re-used from an infection control perspective.

MTA apexification combined with conventional root canal retreatment.

Apexification aims to induce apical closure of the open root apex with a hard-tissue barrier, against which a root filling can be compacted. Despite the popularity of the apexification procedure, calcium hydroxide therapy has some disadvantages that include variability of treatment time, unpredictability of apical closure, difficulties with patient follow-up and delayed treatment. Mineral trioxide aggregate (MTA) is a potential apical barrier material with good sealability and a high degree of biocompatibility. This paper demonstrates the placement of an apical barrier using MTA as an alternative to conventional long-term calcium hydroxide therapy.