Journal of Orofacial Orthopedics-Fortschritte Der Kieferorthopadie最新文献

Objective: Precise root torque adjustment of anterior teeth is indispensable for optimizing dental esthetics and occlusal stability in orthodontics. The efficiency of traditional rectangular archwire manipulation within bracket slots seems to be limited. The crimpable gate spring, a novel device, has emerged as a promising alternative. Yet, there is a paucity of guidelines for its optimal clinical application. This study used finite element analysis (FEA) to investigate the biomechanical impact of the gate spring on torque adjustment of individual anterior teeth and to elucidate the most effective application strategy.

Methods: A FEA model was constructed by a maxillary central incisor affixed with an edgewise bracket featuring a 0.022 × 0.028 inch (in) slot. A range of stainless steel rectangular archwires, in conjunction with a gate spring, were modeled and simulated within the bracket slots. A control group utilized a conventional rectangular wire devoid of a gate spring. Palatal root moments were standardized to 9, 18, and 36 Nmm for both experimental and control groups.

Results: The gate spring significantly amplified palatal root movement, notably with the 0.019 × 0.025 in archwire. However, this was accompanied by an increase in stress on the tooth and periodontal ligament, particularly in the cervical regions. The synergistic use of a 0.019 × 0.025 in rectangular archwire with a gate spring in a 0.022 × 0.028 in bracket slot was identified as most efficacious for torque control of individual anterior teeth.

Conclusions: The gate spring is a viable auxiliary device for enhancing torque adjustment on individual teeth. However, caution is advised as excessive initial stress may concentrate in the cervical and apical regions of the periodontal ligament and tooth.

Purpose: The aim was to investigate the influence of three different three-dimensional (3D)-printed bonding tray designs and professional experience on accuracy of indirect bracket placement.

Methods: Virtual bracket placement was performed on a scanned dental model using OnyxCeph software (Image Instruments, Chemnitz, Germany). Three different designs for indirect bonding trays (open, semi-open, and closed design) were created and produced using a 3D printer. To analyze the influence of professional experience, one of the three tray designs was produced twice. In this case, bracket placement was performed by an inexperienced dentist. Bracket positions were scanned after the indirect bonding procedure. Linear and angular transfer errors were measured. Significant differences between the target and actual situation were analyzed using the Kruskal-Wallis and χ² test.

Results: All bonding tray designs resulted in comparable results. The results of the unexperienced dentist showed significantly higher deviations than those for the experienced orthodontist in the torque direction. However, the mean values were comparable. The open tray design exceeded the clinically acceptable limits of 0.25 mm and 1° more often. The inexperienced dentist exceeded these limits significantly more often than the experienced orthodontist in the vertical and torque direction. The immediate bracket loss rate showed no significant differences between the different tray designs. Significantly more bracket losses were observed for the inexperienced dentist during the procedure compared to the experienced orthodontist.

Conclusions: The bonding tray design and professional experience had an influence on the exceedance of clinically relevant limits of positioning accuracy and on the bracket loss rate.

Purpose: The aim of this study was to investigate the influence of mechanical strain on clock gene function in periodontal ligament (PDL) cells. Furthermore, we wanted to analyze whether effects induced by mechanical stress vary in relation to the circadian rhythm.

Methods: Human PDL fibroblasts were synchronized in their circadian rhythm with dexamethasone and stretched over 24 h. Unstretched cells served as controls. Gene expression of the core clock genes were analyzed at 4 h intervals by quantitative real-time polymerase chain reaction (qRT-PCR). Time points 0 h (group SI1) and 12 h (group SI2) after synchronization served as starting points of a 4 h force application period. Collagen-1α (COL-1α/Col-1α), interleukin-1β (IL1-β), and runt-related transcription factor 2 (RUNX2/Runx2) were assessed by qRT-PCR and enzyme-linked immunosorbent assay (ELISA) after 2 and 4 h. Statistical analysis comprised one-way analysis of variance (ANOVA) and post hoc tests.

Results: After synchronization, the typical pattern for clock genes was visible in control cells over the 24 h period. This pattern was significantly altered by mechanical strain. Under tensile stress, ARNTL gene expression was reduced, while Per1 and 2 gene expression were upregulated. In addition, mechanical stress had a differential effect on the expression of Col-1α and IL1‑β depending on its initiation within the circadian rhythm (group SI1 vs group SI2). For RUNX2, no significant differences in the two groups were observed.

Conclusion: Our results suggest that mechanical stress affects the molecular peripheral oscillator of PDL cells. Vice versa, the circadian rhythm also seems to partially influence the effects that mechanical stress exerts on PDL cells.

Purpose: Anterior arch length (AL) and the alterations in its dimension following incisor movements were shown to be predictable for an individual patient using a mathematical-geometrical model based on a third-degree parabola. Although the model has been validated previously, it is hard to apply in daily orthodontic routine. Thus, the aim of this study was to modify the model using different approaches to allow its establishment in daily routine.

Methods: This retrospective study was based on a study collective, which was described previously and consisted of 50 randomly chosen dental casts and lateral cephalograms taken before (T0) and after (T1) orthodontic treatment with fixed appliances. A JAVA computer program (Oracle, Austin, TX, USA) was developed to predict AL changes following therapeutic changes of arch width, depth or incisor inclination/position, taking the type of tooth movement into account. Performing exemplary AL calculations with the computer program, general rules and nomograms were set up, followed by multiple linear regression analyses to establish easy-to-use regression equations.

Results: The JAVA computer program is available for download. Sagittal changes showed more effect on AL than transverse modifications. Protruding incisors increased AL, but also reduced overbite. The extent of alteration in AL depended on the initial depth, width, incisor inclination, tooth movement type and distance between the incisal edge and the centre of rotation.

Conclusions: The computer program precisely predicts individual changes in AL but is time-consuming. The presented regression equations and nomograms, considering metric variables, are easier to apply clinically and the differences compared to the AL calculated by the computer program are negligible.

Objectives: Aligned teeth commonly convey a positive impression to other people. This study aimed to examine the effect of malocclusion on adult facial perceptions using self-reported and quantitative measures.

Materials and methods: Facial photographs of 15 adult patients (11 women; 47.73 years, standard deviation [SD] = 8.86; 12 periodontally compromised) with malocclusion were acquired before (MT0) and after treatment (MT1). The control group (CG) comprised 15 age-matched adults (12 women; 42.93 years, SD = 7.50) without malocclusion. In all, 37 laypersons (18 women; 41.06 years) viewed all pictures. Self-report: Participants rated each face regarding dental condition, smile valence, and friendliness. Eye-tracking: Visual attention was analyzed by entry time and fixation time on predefined face areas.

Results: MT0 pictures received significantly (p < 0.001) more negative ratings regarding dental condition, smile valence, and friendliness. Ratings for MT1 were comparable to those of the control group. Compared with the CG, MT0 faces showed faster first fixations on the mouth (p = 0.005) and had longer fixation durations (36.15%, p < 0.001). After treatment, the difference to the CG decreased significantly (12.38%, p = 0.014).

Conclusion: Malocclusions have a negative effect on the perception of individuals in terms of gaze behavior and self-reported ratings. These effects decrease after treatment, underlining the effect of orthodontic correction.

Clinical relevance: Orthodontic treatment improves facial perception and the assessment of oral regions, highlighting the psychosocial significance of orthodontic treatment.

Aim: To investigate the agreement between palatal bone thickness (PBT) measurements performed on lateral cephalograms and cone-beam computed tomography (CBCT) images in a group of white patients considering different facial patterns.

Materials and methods: Measurements performed on lateral cephalograms and CBCT images from 60 white patients (39 females and 21 males; 24.1 ± 6.4 years) were retrospectively compared. On lateral cephalograms, PBT values were measured by drawing lines perpendicular to the maxillary occlusal plane (MOP) at the point of contact between the first and second premolar (P1-P2), second premolar and first molar (P2-M1), and first and second molar (M1-M2), as well as at the buccal cusps of the second premolar (P2) and first molar (M1). On CBCT images, they were measured at the same landmarks at 2 mm, 4 mm, 6 mm and 8 mm off-centre to the midpalatal suture. Vertical facial pattern of the patients was determined using the Frankfort-mandibular plane angle (FMA). Analysis of variance (ANOVA) and Tukey post hoc tests were used to ascertain the degree of agreement between the two measurement sets (p < 0.05), subsequently quantified by intraclass correlation coefficient (ICC) tests.

Results: Good agreement was found at all investigated sites regardless of vertical facial pattern, except at sites P1-P2 and P2 (8 mm off-centre) and M1 and M1-M2 (2 mm off-centre; p < 0.05). The two measurement sets displayed excellent agreement (ICC > 0.8) at P1-P2 (4 mm off-centre), at P2 (2, 4 and 6 mm off-centre), and all P2-M1 sites.

Conclusion: The lateral cephalogram can be a viable option for digital planning of palatal miniscrews insertion, with the preferred sites being P1-P2 at 4 mm off-centre and P2 at 4 and 6 mm off-centre in selected cases for adolescents and young adults. No significant differences in the degree of agreement between the two sets of PBT measurements were found among the different vertical facial patterns.

Objective: Nonsyndromic oral clefts (NSOC) result from disruptions in the development of the primary and secondary palate and are categorized into cleft lip (CL), cleft lip and palate (CLP) and cleft palate (CP). NSOC is a condition with complex genetically heterogeneous backgrounds for that several genes might be involved. Thus, this study investigated whether functional single nucleotide polymorphisms (SNPs) in genes that potentially influence the vitamin D levels and parathyroid hormone (PTH) levels are associated with NSOC.

Materials and methods: Brazilian individuals with NSOC-presenting cleft lip (CL), cleft lip and palate (CLP) and cleft palate (CP)-and a comparison group were selected. Individuals' DNA was obtained from epithelial cells of the oral mucosa. Nine SNPs in five genes (VDR, CYP27B1, CYP24A1, SEC23A and PTH) were selected. Genotyping was performed by real-time polymerase chain reaction (PCR). The association between NSOC and vitamin D related polymorphisms was analyzed by Χ² test at a significance level of p < 0.005 (after Bonferroni correction).

Results: The sample consisted of 274 individuals: 154 NSOC individuals and 120 controls. A total of 43 (27.9%) had CL, 91 (59.1%) had CLP and 20 (13.0%) had CP. After Bonferroni correction, none of the SNPs were associated with NSOC (p > 0.005).

Conclusion: None of the studied SNPs in vitamin D related and parathyroid hormone genes were associated with NSOC.

Aim: This systematic review aimed to assess and quantify the dentoalveolar compensation in skeletal class III malocclusion subjects.

Materials and methods: Untreated class III subjects whose dentoalveolar compensations were radiologically evaluated were included. Predetermined inclusion and exclusion criteria were applied across PubMed, Scopus, LILACS, Ovid, and Web of Science electronic databases up to 27 January 2025, with no restriction on the year of publication. A total of 1007 articles were obtained, of which 10 studies met the eligibility criteria and were included in the systematic review, while 7 were included for the meta-analysis.

Results: Risk of bias assessment was performed using the Newcastle Ottawa scale. Four studies scored 8 points, four studies scored 7 points, and two studies scored 6 points. The qualitative evaluation indicated that the dentoalveolar compensation in class III malocclusion was a result of proclined maxillary and retroclined mandibular incisors. Quantitative evaluation showed that when compared to class I subjects, maxillary incisors in class III subjects were proclined by 4.75° (95% confidence interval [CI] 0.72-8.77). Mandibular incisors were retroclined with a mean change in inclination of -8.40° (95% CI -11.21 to -5.60), thus, indicating a greater contribution of mandibular incisors to the compensatory mechanism.

Conclusion: The present systematic review and meta-analysis conclusively proved that maxillary incisor proclination and mandibular incisor retroclination contributed to dentoalveolar compensation in class III subjects. Quantitative analysis provided evidence that mandibular incisor retroclination contributed more to dentoalveolar compensation. The findings of this systematic review and meta-analysis would be of importance to the clinician while planning treatment, since respecting the anatomical limits of the underlying structures is essential.

Purpose: The goal is to assess long-term oral health-related quality of life in adults who had previously undergone compensatory orthodontic treatment for class III malocclusion and to identify associated factors.

Methods: A total of 26 patients who underwent treatment by dental compensation more than 5 years ago were followed for an average of 14 years and were evaluated using cephalograms, photographs, the Oral Health Impact Profile (OHIP)-14 questionnaire, and self-perception questions on treatment stability. Poisson regression was used to analyze the association between quality of life and the stability of class III treatment, considering posttreatment cephalometric measurements, sex, posttreatment age (T2), treatment and posttreatment duration, use of retainers, tooth extractions, gingival recession, and clinical changes in incisor alignment.

Results: The median OHIP-14 score was 3 (range 0-8.5), indicating a good level of quality of life over the long-term. In all, 30.76% of patients reported minor worsening in treatment results after its completion. When asked to identify the observed changes that occurred after treatment, whether in the teeth, face, or both regions, 80% associated the worsening with the dental region. Of these, 90% reported willingness to undergo orthodontic retreatment. Only 12% of the variation in OHIP-14 scores was attributed to the chosen predictor variables, and none of the analyzed variables showed a significant association with quality of life (p = 0.20-0.99).

Conclusion: Adults with class III malocclusion subjected to treatment with dental compensation reported a good OHRQoL in the long-term, even in the presence of minor posttreatment changes. Cephalometric changes, clinical and assessed demographic factors did not significantly impact quality of life.