Prognostic risk factors for apical root resorption in orthodontic patients - Are the Kjær's morphologic characteristics of clinical relevance?

BACKGROUND: Patients undergoing orthodontic treatment (OT) face an increased risk of developing external apical root resorption (EARR). A prognostic risk assessment prior to OT can potentially be conducted through anatomical features in panoramic radiography. This retrospective study aimed to assess the significance of Kjær's morphological characteristics in analyzing the risk of EARR. METHODS: Panoramic radiographs of 1,156 patients (624 females, 532 males) were retrospectively analyzed. Anamnestic and treatment-related data were extracted from patient records. The mean age at the start of OT was 12.8 ± 2.2 years (min. 6.4 years, max. 22.3 years) and at the end of OT 15.9 years (min. 8.5 years, max. 24.1 years). The mean treatment duration was 3.1 ± 1.6 years. Panoramic radiographs with a minimum of two per patient were examined for the presence of Kjær's characteristics. The degree of EARR was registered defining resorption in four degrees of severity. Bivariate analysis and multivariate Poisson regression were performed to assess the association between Kjær's characteristics and EARR patient- and tooth- related (α = 0.05). RESULTS: In total, 72.8% of the patients showed EARR at the end of OT with lateral maxillary incisors most frequently affected. Short roots (p < 0.001) were significantly associated with EARR in patients. Tooth-related microdontia (#12, #22, lower second premolars), narrow crowns (#11, #21, lower incisors), short roots (upper incisors, lower first molars) and ectopia (#11, #21, #13), such as shorter distal roots of the mandibular first molar showed a significant association with EARR depending on severity degree. The type of orthodontic appliance (fixed: p < 0.001, fixed and removeable: p = 0.008), as well as treatment duration (p < 0.001) were also identified as risk factors for EARR. CONCLUSIONS: Although the risk assessment for EARR development through panoramic radiography analysis is limited, predisposition appears to be present in specific dental characteristics and treatment-related factors.

Impact of initial lip competence on the outcome of class II functional appliances therapy.

OBJECTIVES: The aim of this prospective clinical study was to evaluate the impact of initial lip position on class II functional appliance therapy. MATERIALS AND METHODS: In total, 34 class II division 1 patients (23 females, 19 males; mean age 12.4 ± 0.9 years) that met the inclusion criteria (> ½ class II molar relationship, overjet > 6 mm, ANB > 4°, neutral or horizontal growth pattern, cervical vertebral maturation stage (CVMS) II - III, mean wear-time > 10 h/day) were consecutively divided into two groups (lip incompetence (LI); lip competence (LC)). All patients were treated with the Sander bite jumping appliance (BJA). Wear time was microelectronically measured. Lateral cephalograms were taken at the beginning (T0) and after 1 year of treatment (T1). An untreated class II group served as a control (CG). Inter-group comparisons were determined with Mann-Whitney U tests for independent samples. RESULTS: Significant skeletal treatment effects were found in both treated groups when compared to the CG with significantly more pronounced mandibular skeletal effects in the LI than in the LC group (mandibular base length p < 0.001, composite mandibular base length p < 0.001, condylar head growth p = 0.002, co-pg p < 0.00, go-pg p = 0.003, reduction of the ANB angle p = 0.009, and Wits appraisal p < 0.001). CONCLUSION: The more pronounced mandibular effects in the LI group were composed of the functional orthopedic effect plus harmonization of the lip competence. CLINICAL RELEVANCE: Functional harmonization of lip incompetence with BJA enhances mandibular growth stimulation. Lip incompetence seems to impede mandibular growth and its harmonization seems to be a preventive approach.

[The upper airway in obstructive sleep apnea patients is pathological even when awake]. / Der obere Atemweg bei OSA-Patienten ist auch im Wachzustand pathologisch.

Obstructive sleep apnea (OSA) is characterized by partial or complete obstruction of the pharyngeal airway. Anatomical factors can be distinguished from non-anatomical factors. Age and obesity are the main risk factors for OSA; however, approximately 50% of patients are not obese. In older patients (>60 years), the importance of obesity decreases. There is an increased prevalence of OSA among patients with normal weight. The effects of chronic intermittent hypoxemia, low-grade inflammation, increased sympathetic tone and mechanical stress contribute to a transformation of muscle fibers in the upper airway, resulting in reduced muscle mass and strength. Less frequently encountered non-anatomical factors include decreased muscle tone, increased arousal threshold, and altered sensitivity of CO2 chemoreceptors.

Use of bioluminescence measurements for detection of artificial demineralization adjacent to orthodontic brackets.

PURPOSE: Enamel demineralization can occur as a side effect during orthodontic treatment with fixed appliances and should be detected as early as possible. A new approach to assess demineralization is a system consisting of a photosensitive protein that binds to free calcium ions at the enamel surface. A camera is then used to visualize the bioluminescence spots. This in vitro study aimed to evaluate the ability of the bioluminescence technology to assess artificially demineralized enamel adjacent to various orthodontic brackets. METHODS: In all, 108 human enamel samples were allocated randomly to groups with different orthodontic bracket material: stainless steel, titanium, ceramic. Initial lesions were created adjacent to the brackets. The samples were assessed by bioluminescence before and after demineralization. Images were assessed for presence of bioluminescence spots (yes/no). To quantify the bioluminescence measurements, the images' pixel values (P) were calculated within a defined area (F) adjacent to each bracket before and after demineralization. Quantitative light-induced fluorescence measurements (ΔF, ΔQ) were performed as the reference standard for demineralization. RESULTS: After demineralization, bioluminescence spots were visible (yes/no decision) in 87% of the samples. The pixel analysis of the bioluminescence spots showed significantly higher pixel values after demineralization compared to baseline (p < 0.0001). The bracket material had no influence on the bioluminescence measurements. All samples showed fluorescence loss with a median ΔF of -9.52% (±3.15) and a median ΔQ of -1.01%â€¯× mm2 (±3.34), respectively. CONCLUSION: The bioluminescence technology is a promising tool to demonstrate demineralization adjacent to different orthodontic brackets in vitro.