Bisphenol-A release from thermoplastic clear aligner materials: A systematic review.

AIM: The aim of the present study was to undertake a systematic review of the available evidence on the release of bisphenol-A (BPA) from thermoplastic materials used in the fabrication of clear aligners (CA). METHODS: Electronic databases, such as MEDLINE (via PubMed), Google Scholar, Scopus, Cochrane Library, Web of Science, OpenGrey, and the U.S. National Institute of Heath-Clinical Trials, were searched up to 27 October 2022. In vivo/in vitro studies that assessed the release of BPA from different thermoplastic CA materials, with or without a control group, were selected. The risk of bias (RoB) in the randomised controlled trials (RCT) and in vitro studies was assessed using the Cochrane RoB tool and the guidelines for the reporting of pre-clinical studies, respectively. The quality of evidence was determined using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) Pro tool. RESULTS: Six studies were considered for review from a total of 1926 records. This included one RCT and five in vitro studies. Only two studies found leaching of BPA, while four did not report any traces. The RoB was found to be moderate to high. The GRADE evidence level ranged from low to very low. Five of the included studies were conducted in vitro. Significant heterogeneity among the included studies prevented a quantitative synthesis. CONCLUSION: In light of the available conflicting evidence, BPA release from CAs can neither be confirmed nor denied. Safety remains questionable until high-quality in vivo trials prove otherwise. REGISTRATION: PROSPERO CRD42022310434.

How effective is maxillary expansion as an interceptive treatment in individuals with palatally displaced canines? A systematic review and meta-analysis.

BACKGROUND: The objective was to provide a synthesis of the existing literature on the effectiveness of maxillary expansion in intercepting palatally displaced canines (PDCs). METHODS: Studies that evaluated the effectiveness of maxillary expansion in subjects with PDCs in the mixed dentition period were included. The following electronic databases were searched until November 30, 2021: MEDLINE (via PubMed), Scopus, Google Scholar, Web of Science, and Cochrane library. Grey literature search and manual search were also performed. The risk of bias was assessed using the Cochrane tool for the one randomized controlled trial (RCT) and the ROBINS-I tool for the non-RCTs. The data were extracted and meta-analysis was performed using RevMan 5.4. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach was used to assess the certainty of evidence. RESULTS: Four studies were selected from 9,586 records, which included one RCT and three non-RCTs. The former demonstrated a high risk of bias whereas the non-RCTs showed moderate risk. The meta-analysis of three non-RCTs found no significant improvement in the alpha angle of canines after rapid maxillary expansion, with a difference of -4.26 (95% CI -11.41 to 2.89; P = 0.24). The RCT showed an increase in the eruption rate of high-risk canines with rapid maxillary expansion. Slow maxillary expansion did not demonstrate any favorable change. The level of evidence ranged from low to very low. CONCLUSIONS: There is insufficient evidence to recommend the use of maxillary expansion as a stand-alone procedure in intercepting PDCs. Additional well-conducted trials are required.

Comparison of the effect of labiolingual inclination and anteroposterior position of maxillary incisors on esthetic profile in three different facial patterns.

OBJECTIVE: To test the null hypothesis that there is no effect of esthetic perception of smiling profile in three different facial types by a change in the maxillary incisor inclination and position. MATERIALS AND METHODS: A smiling profile photograph with Class I skeletal and dental pattern, normal profile were taken in each of the three facial types dolichofacial, mesofacial, and brachyfacial. Based on the original digital image, 15 smiling profiles in each of the facial types were created using the FACAD software by altering the labiolingual inclination and anteroposterior position of the maxillary incisors. These photographs were rated on a visual analog scale by three panels of examiners consisting of orthodontists, dentists, and nonprofessionals with twenty members in each group. The responses were assessed by analysis of variance (ANOVA) test followed by post hoc Scheffe. RESULTS: Significant differences (P < 0.001) were detected when ratings of each photograph in each of the individual facial type was compared. In dolichofacial and mesofacial pattern, the position of the maxillary incisor must be limited to 2 mm from the goal anterior limit line. In brachyfacial pattern, any movement of facial axis point of maxillary incisors away from GALL is worsens the facial esthetics. The result of the ANOVA showed differences among the three groups for certain facial profiles. CONCLUSION: The hypothesis was rejected. The esthetic perception of labiolingual inclination and anteroposterior of maxillary incisors differ in different facial types, and this may effect in formulating treatment plans for different facial types.

A Comparative Study of Three Types of Rapid Maxillary Expansion Devices in Surgically Assisted Maxillary Expansion: A Finite Element Study.

OBJECTIVES: The aim of this study was to analyze the displacement pattern and stress distribution during surgically assisted rapid maxillary expansion (RME) with three different types of RME devices by constructing a finite element model. MATERIALS AND METHODS: A finite element model is constructed from the computerized tomography scans. According to the type of RME device, 3 groups were simulated on this mesh model. The experimental groups were as follows; Group I (tooth borne appliance), Group II (bone borne appliance), and Group III (hybrid appliance). A Le fort I osteotomy with bilateral pterygomaxillary disjunction and midpalatal split osteotomy cuts were incorporated in all the groups. The displacement pattern and stress distribution for each 1 mm of activation of appliance up to 10 mm is noted and analyzed. The data were analyzed using Student's t-test, Analysis of Variance and Duncan new multiple range test. RESULTS: Tooth borne appliance has more rotational tendencies. The bone borne and the hybrid appliance exhibited similar stress patterns for the dissipation of the forces produced by RME appliances. The pivoting effect decreased with the hybrid and the bone borne appliance and can be utilized in patient with hyper divergent growth. CONCLUSION: The pivoting effect is least with the hybrid appliances.

A comparison between cervical vertebrae and modified MP3 stages for the assessment of skeletal maturity.

OBJECTIVE: Evaluation of skeletal maturity in human individuals is an important aspect in orthodontics and dentofacial orthopedics because, growth guidance and fundamental structural changes are essential for treatment of skeletal discrepancies in all the three planes. Among various growth assessment methods, cervical vertebra maturation stages and hand wrist have been correlated with the individual growth changes during puberty. The purpose of this study is to determine correlation of the CVM index with the modified median phalanx index (MP3) as described by Rajagopal and Kansal. MATERIALS AND METHODS: 200 subjects (100 males and 100 females) of Nellore, Indian origin boys aged between 10 to 19 years and girls of 8 to 16 years were selected for the study. The subjects are selected randomly from patients visiting the Departments of Orthodontics and Dentofacial Orthopedics, Pediatric dentistry and Oral medicine and Radiology at Narayana Dental College and Hospital. Nellore. Radiographs of left hand MP3 and lateral cephalogram were taken. RESULTS: Cohen's kappa statistic was used to assess the agreement between the two measurements based on categorical variables. CONCLUSIONS: There was a good concordance between 6 stages of CVMI (Hassel and Farman) and the 6 stages of MP3 (Rajagopal and Kansal). Physiological maturity was earlier in females than in males when compared to the individuals of opposite sex of same chronological age. Chronological age was not a valid predictor of assessing the skeletal maturity because of significant variations in the distribution of CVMI and MP3 stages with respect to individual chronological age distribution.

Evaluation of arch width variations among different skeletal patterns in South Indian population.

BACKGROUND: Anterior cranial base can be taken as a reference line (SN) to determine the steepness of mandibular plane. Subjects with high mandibular plane angle tend to have a long face and one with low MP-SN angle has a shorter face. OBJECTIVE: This study was done to investigate if dental arch widths correlated with vertical facial types and if there are any differences in arch widths between untreated male and female adults in South Indian population. MATERIALS AND METHODS: Lateral cephalogram and dental casts were obtained from 180 untreated South Indian adults (90 males and 90 females) above 18 year old with no cross bite, minimal crowding and spacing. The angle between the anterior cranial base and the mandibular plane was measured on lateral cephalogram of each patient. Dental casts were used to obtain comprehensive dental measurements including maxillary and mandibular inter canine, inter premolar and inter molar widths, as well as amount of crowding or spacing. RESULTS: The results showed that male arch widths were significantly larger than those of females (P < 0.05) and there was a significant decrease in inter arch width as the MP-SN angle increased in untreated adult South Indian population. The results obtained in our study when compared with studies done in other population groups showed that there is difference in inter arch widths according to ethnicity and race. CONCLUSION: It was concluded that the dental arch width is associated with gender, race and vertical facial morphology. Thus using individualized arch wires according to each patient's pre treatment arch form and width is suggested during orthodontic treatment.