Journal of Orthodontics最新文献

Objective: To assess the influence of varying degrees of gingival display on perception of smile aesthetics judged by orthodontists, dentists and lay people.

Design: Cross-sectional study.

Setting: Barts and the London, School of Medicine and Dentistry, Queen Mary University of London, UK.

Participants: Three groups of raters comprising 25 orthodontists, 25 dentists and 25 lay people.

Methods: Videos in increments of 1.5 mm of the final lip position ranging from 3 mm incisal coverage to 7.5 mm of gingival display were produced. Three rater groups assessed the attractiveness of smile videos using a visual analogue scale (VAS). Multiple regression analysis was undertaken, and images were compared using the Tukey HSD method.

Results: The intraclass correlation coefficient (ICC) was 0.65% (95% confidence interval 0.59-0.71), indicating moderate intra-rater reliability. The highest ranking for female videos was with 1.5 mm of incisal coverage, with no significant difference between 3 mm of incisal coverage and 3 mm of gingival exposure. For the male videos, the highest ranking was 0 mm of gingival show, with no significant difference between 1.5 mm of incisal coverage and 1.5 mm of gingival exposure. There was a significant drop in the scores with further increase in gingival exposure, with more than 6 mm being rated very low aesthetically. Video rating was not influenced by rater group (female: P = 0.60; male: P = 0.06), rater gender (female: P = 0.17, male: P = 0.74) or rater age (female: P = 0.16, male: P = 0.25).

Conclusion: There is a significant difference in the perception of smile aesthetics with varying amounts of gingival show. There is a clear threshold of acceptance up to 3 mm of gingival display for the female videos and 1.5 mm in for the male videos, after which the aesthetics of the smile decline with increments of increasing gingival display. No significant differences were observed in the perception of smile aesthetics with varying amounts of gingival show between orthodontists, dentists and lay people.

Objective: To investigate the impact of appliance removal on oral microbial diversity, composition, and abundance using metagenomic sequencing. It aims to identify the core microbiome and assess changes between mid-treatment and 2 weeks after debonding to understand the relationship between orthodontic therapy and oral health better.

Methods: This longitudinal cohort study recruited 26 patients undergoing fixed orthodontic treatment between January 2022 and June 2023. Saliva samples were collected at two predefined time points: mid-treatment (T0, defined as before appliance removal) and 2 weeks after debonding (T1). Microbial DNA was extracted and the V1-V3 hypervariable regions of the 16S rRNA gene were sequenced using Illumina NovaSeq. Bioinformatics analysis was performed using QIIME and the SILVA database to evaluate microbial diversity and composition at T0 and T1. Beta diversity metrics and statistical tests, including PERMANOVA and Wilcoxon signed-rank tests, were applied to identify significant differences (P < 0.05). Effect sizes with 95% confidence intervals (CIs) were reported.

Results: The analysis revealed significant shifts in microbial diversity and composition between T0 and T1. A total of 189 species across 63 genera were identified, with Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, and Fusobacteria as dominant phyla. Genera such as Fusobacterium periodonticum (↑ 12.4%, 95% CI = 10.1-14.7) and Veillonella parvula (↑ 9.8%, 95% CI = 7.6-11.3) increased after debonding, while Prevotella melaninogenica (↓ 10.2%, 95% CI = 8.1-12.0) and Rothia dentocariosa (↓ 7.9%, 95% CI = 6.3-9.2) decreased. Beta diversity analysis confirmed a statistically significant microbial community shift (P < 0.05).

Conclusion: This study demonstrated significant microbial shifts between mid-treatment and 2 weeks after debonding, including increases in potentially pathogenic genera and alterations in the core microbiome. These findings indicate microbial changes persist for at least 2 weeks after appliance removal. Further research with pre-treatment baselines and extended follow-up is required to better define the long-term trajectory of these changes.

Objective: To compare the quality of orthodontic clinical photographs taken with a mirrorless camera and a smartphone compared with those taken with a digital single lens reflex (DSLR) camera.

Methods: This cross-sectional study involved six participants (models), each of whom had five extra-oral and five intra-oral photographs taken using a DSLR (Canon 70D), a mirrorless camera (Canon RP) and a smartphone (iPhone 14 Pro), resulting in a total of 180 photographs. Four orthodontists served as assessors, evaluating the quality of each photograph based on image clarity, colour accuracy and lighting. They categorised the photographs as 'good' (no errors), 'acceptable' (some errors) or 'unacceptable', while also noting any specific errors observed. Statistical analysis was conducted using Fisher's exact test and Pearson's chi-square test. All statistical tests were interpreted at a significance level of 5%.

Results: Compared to the DSLR camera, the photographs taken with the mirrorless camera were of identical quality, with 100% of photographs rated as good for each camera. For the smartphone camera, 41.7% were assessed as good and 58.3% as acceptable, which was significantly less (P < 0.001) than for the DSLR (100% good). For smartphone intra-oral photographs, the majority of 'upper occlusal' and 'lower occlusal' photographs were classified as 'good' (62.5%), while the remaining 37.5% were rated as 'acceptable'. In contrast, for 'right buccal' and 'left buccal' photographs, the majority of photographs (87.5%) were categorised as 'acceptable', with only 12.5% rated as 'good'.

Conclusion: In conclusion, although DSLR and mirrorless cameras consistently produce high-quality orthodontic photographs suitable for all clinical and professional purposes, smartphone cameras fall short in photographic quality. Given their lower resolution and pixel count, smartphone-captured photographs may be adequate for clinical records but are not recommended for large-format applications.

Ectopic eruption of the first permanent molar is prevalent in children, with a reported prevalence of up to 6%. Treatment options usually range from passive observation to active correction with orthodontic appliances like separators or distalising devices. This study outlines the step-by-step procedure for creating a 'pistol spring' system, which delivers a consistent, sustained force, reducing the need for frequent reactivation. The system is easy to fabricate, well-tolerated and enhances treatment efficiency, improving patient compliance and reducing chair-side time. The 'pistol spring' offers a cost-effective, time-efficient solution for managing ectopic first molars, particularly in paediatric patients with limited appointment availability.

Objective: To develop a protocol for locating the Xi point using three-dimensional (3D) cone-beam computed tomography (CBCT) and to evaluate the linear distance between the Xi point and the mandibular foramen on the CBCT image.

Study design: A retrospective cross-sectional study.

Study setting: The study was conducted on standardised CBCT records of 35 patients aged >18 years (13 men, 22 women). The CBCT scans were analysed using Dolphin 3D 11.9 software.

Methods: The Xi point was constructed on the right and left lateral views of the ramus using the four points R1, R2, R3 and R4 based on Ricketts' analysis. The mandibular foramina were located on CBCT and the linear distance from the mandibular foramen to the Xi points were recorded.

Results: The 3D Xi point was located on the lateral surface of the mandibular ramus superior and distal to mandibular foramen. The mean distance of the Xi point from the mandibular foramen was 2.3 ± 1.46 mm on right side and 2.3 ± 1.53 mm on left side.

Conclusion: The study identified the accuracy of Xi point construction and its linear relation to the mandibular foramen. Xi point validation in relation to the mandibular foramen serves as a guide for inferior alveolar nerve course identification. The results of the study also find applications in bone screw placement and growth prediction.

Objective: To examine the palatal bone thickness in a cohort of Portuguese patients representing various age groups to identify optimal insertion sites for enhancing the stability of orthodontic micro implants (MIs). To ascertain whether there are any age- or sex-related variations in palatal bone thickness.

Design: Retrospective observational study.

Method: A total of 50 cone-beam computed tomography (CBCT) scans of patients aged 12-51 years (23 boys/men and 27 girls/women) were analysed. The CBCT scans were grouped according to age and sex. The palatal bone thickness was measured at five points: 4, 8, 12, 16 and 20 mm posterior to the incisive foramen (IF) and at 3, 6 and 9 mm lateral to the midpalatal suture (MPS). A total of 750 regions of interest were evaluated (15 for each of 50 patients). Two-way analysis of variance (ANOVA) and Student's t-tests were employed for data analysis, with a significance level of P < 0.05.

Results: The greatest thickness of palatal bone was found to be at 4 mm posterior to the ІF and 9 mm lateral to the MPS in all investigated groups, with a mean thickness of 12.29 ± 2.00 mm for girls/women and 13.59 ± 2.31 mm for boys/men; 13.30 ± 2.38 mm for adolescents and young adults, and 12.27 ± 2.03 mm for adults. Significant statistical differences were identified between male and female individuals and between different age groups (ANOVA, P < 0.05).

Conclusion: Palatal bone thickness varied with sex and age; thus, these factors must be considered when selecting the appropriate length of MIs. In general, girls/women had a thinner palatal bone than boys/men. The palatal bone was significantly thicker in the adolescent and young adult age group (12-25 years) than in the adult age group (27-51 years). In addition, bone thickness decreased posteriorly within each sagittal section.