Digital analyses of Bolton tooth size ratios and their association to gender, angle class, and other occlusal traits: a study using a partially automated digital 3D model analysis.

BACKGROUND: This study aims to verify Bolton's values for tooth size ratios and to evaluate possible relationships to different occlusal traits using precise digital measurement methods. MATERIALS AND METHODS: Including 1000 consecutively selected patients from three study centres a digital, partially automated model analysis was performed utilizing the software OnyxCeph. The measurements comprised tooth width for calculation of anterior (AR) and overall ratio (OR) as a percentage, arch width, length, perimeter, overjet, overbite, space analysis in millimetre and the assessment of the angle classification. RESULTS: AR and OR were significantly increased compared to Bolton's ratios of 77.2% (AR) and 91.3% (OR). In the gender comparison, male patients showed larger tooth size ratios, especially in the OR. Patients with Angle Class II/1 and II/2 had smaller tooth size ratios than patients with Angle Class III and I. Thus, patients with Angle Class II/1 had the largest tooth diameters in all maxillary teeth and with Angle Class II/2 the smallest tooth sizes in the mandible. The largest tooth widths in the lower jaw were observed in the Angle Class III patient group. Furthermore, a negative correlation from AR/OR to overjet, overbite, and available space in lower jaw as well as a positive correlation to available space in upper jaw was detected. CONCLUSIONS: There is a clear correlation between the tooth size ratios and the present dysgnathia as well as other orthodontically relevant occlusal traits. This prior knowledge about our patients is extremely important to create an individualized treatment plan and enable sufficient occlusion. To achieve a functionally good occlusion with correct overjet and overbite, it is essential that the maxillary and mandibular teeth are proportional in size. Any deviation from the ideal patient in terms of tooth size, number, shape, or arch must be considered in the pre-therapeutic treatment plan in combination with the existing dysgnathia in order to be able to achieve a stable anterior and posterior occlusion with appropriate adjustments to the therapy post-therapeutically.

Orthodontic treatment quality evaluated by partially automated digital IOTN and PAR index determination: a retrospective multicentre study.

BACKGROUND: Orthodontic therapy aims to treat misaligned teeth and jaws to improve dental occlusion as well as the function and aesthetics of the masticatory system. Continuous data collection to check treatment quality is of great importance for the constant optimization of orthodontic care. OBJECTIVE: The aim of this retrospective multicentre cohort study was to systematically determine the outcome and quality of orthodontic treatment by applying the internationally established Index of Orthodontic Treatment Need (IOTN) and Peer Assessment Rating (PAR) index in multiple clinical settings for a representative number of patient cases. MATERIALS AND METHODS: A total of 1509 consecutive orthodontic patient cases (treatment completion between January 2018 and December 2020) from three representative orthodontic centres (University clinic, city office, small town office) were analysed in a multicentre study. The pre- and post-treatment casts were scanned, digitally measured, and partially automatically evaluated using the IOTN and PAR indices. RESULTS: A statistically significant improvement in occlusion was observed for medically necessary treatment of IOTN grades 4 and 5 in 97.30 per cent of the analysed cases and for treatment-requiring grades 2 and 3 in 94.08 per cent of the analysed cases. The average percentage PAR improvement was 76.51 per cent. 72.50 per cent of cases showed improvement of more than 70 per cent. The mean PAR index score was reduced from 28.19 ±â€…9.49 to 6.22 ±â€…5.41 points. CONCLUSION: The present data demonstrate that orthodontic treatment is efficient in inducing significant improvement of malocclusions in general and has a high success rate with severe dysgnathia.

TNF reduces osteogenic cell fate in PDL cells at transcriptional and functional levels without alteration of periodontal proliferative capacity.

AIMS: To investigate the effect of tumor necrosis factor (TNF) on the growth of human periodontal ligament (PDL) cells, their osteogenic differentiation and modulation of their matrix secretion in vitro. METHODS: The influence of 10 ng/ml TNF on proliferation and metabolic activity of PDL cells was analyzed by cell counting (DAPI [4',6-diamidino-2-phenylindole] staining) and the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. In addition, cells were cultured under control conditions and osteogenic conditions (media containing 10 mM ß-glycerophosphate). Quantitative expression analysis of genes encoding the osteogenic markers alkaline phosphatase (ALP), collagen type I alpha 1 chain (COL1A1), osteoprotegerin (OPG), and osteopontin (OPN) was performed after 7 and 14 days of cultivation. Calcium deposits were stained with alizarin red. RESULTS: Our studies showed that 10 ng/ml TNF did not affect the survival and metabolic activity of PDL cells. Quantitative expression analysis revealed that long-term cultures with TNF impaired osteogenic cell fate at early and late developmental stages. Furthermore, TNF significantly reduced matrix secretion in PDL cells. CONCLUSION: The present data confirm TNF as a regulatory factor of proinflammatory remodeling that influences the differentiation behavior but not the metabolism and cell proliferation of the periodontium. Therefore, TNF represents an interesting target for the regulation of orthodontic remodeling processes in the periodontium.