The Angle orthodontist最新文献

Objectives: To investigate the accuracy of the Invisalign appliance in achieving predicted angular tooth movement of the maxillary central incisors, to locate the center of rotation in a labio-palatal direction, and to investigate any difference between 1-weekly and 2-weekly wear protocols.

Materials and methods: This study involved a retrospective sample of two groups of 46 Class I adult subjects treated non-extraction with different protocols of 1-weekly and 2-weekly wear. The pretreatment, predicted outcome and achieved outcome digital models were superimposed and measured using metrology software. Angular and center-of-rotation measurements in the sagittal plane for the maxillary right central incisor were analyzed.

Results: There was a statistically significant difference between predicted and achieved angular measurements (P < .005) for labial tooth movements regardless of wear protocol. For palatal movements, no statistically significant difference was observed (P > .05). A small amount of overexpression was observed in some cases. Regarding crown and root control, uncontrolled tipping was the most predictable. No statistically significant difference was found between predicted and achieved center of rotation, but the confidence interval was wide. No statistically significant difference (P > .05) was found between the two wear protocols for the parameters measured.

Conclusions: For maxillary central incisors, labial angular movements were not as accurate as palatal movements. Overcorrection could be recommended with careful clinical monitoring due to the possibility of overexpression. Control of root movements may be unpredictable, and further research is required to draw stronger conclusions. For the parameters measured in this clinical sample, there was no difference between the two wear protocols.

Objectives: To evaluate the influence of facial biotype in the therapeutic effect of mandibular advancement devices (MADs) according to polysomnographic records in patients diagnosed with sleep apnea-hypopnea syndrome (SAHS).

Materials and methods: A total of 46 patients were recruited. Patients were classified according to facial biotype (mesofacial, brachyfacial, or dolichofacial). The quantitative variables were described as the arithmetic mean and standard deviation or the median and interquartile range. Hypothesis tests used were Pearson's chi-square, paired-sample Student's t- test, the Wilcoxon test, one-way analysis of variance, Kruskal-Wallis test, and Mann-Whitney U-test. P < .05 was considered statistically significant.

Results: A total of 46 patients were categorized into three facial biotype subgroups with no significant differences among them in age, body mass index, neck circumference, and sex. The respiratory disturbance index (RDI) results were as follows: brachyfacial patients had a reduction to 15 events/h (P < .001), the mesofacial patients had a reduction to 14 events/h (P < .001), and the dolichofacial patients did not show a significant reduction. The oxygen desaturation index (ODI) results were as follows: brachyfacial patients had a reduction in ODI episodes to 45 episodes/h (P = .001), mesofacial patients had a reduction to 18 episodes/h (P = .001). In the brachyfacial group, the number of awakenings with MAD therapy was reduced to 23 events/h (P = .003), while, in the mesofacial group, it was reduced to 37 episodes/h (P = .012).

Conclusions: The facial biotype influences the effectiveness of MAD therapy and is considered a good predictive factor.

Objectives: To determine the effect of orthodontic pressure on periodontal ligament (PDL) compression in rats and assess correlation between PDL compression and orthodontically induced root resorption (OIRR).

Materials and methods: Eight female Wistar rats aged 10 weeks underwent surgery to place 2 mini-screws at the center of the palatal plate. 25 cN coil springs connecting the maxillary first molars and mini-screws were applied bilaterally to generate mesial force. Maxillary first molars were assigned to undergo either bodily or tipping movements. Micro-computed tomography (μCT) scans were taken on days 0, 3, 7, and 14, and histological sections were taken on day 14. OIRR was measured from histological sections, and the corresponding PDL compression ratio was quantified using μCT images.

Results: The PDL was compressed by approximately 76% in tipping movement and 55% in bodily movement after 3 days, and by approximately 47% in bodily and tipping movements after 7 days of orthodontic force application. The extent of OIRR in tipping movement was significantly greater than that in bodily movement. A strong positive correlation between OIRR and PDL compression ratio was observed on day 3; however, no correlation was observed on day 7.

Conclusions: A strong correlation between PDL compression ratio and OIRR was observed at an early stage after the application of orthodontic force regardless of the tooth movement type (bodily or tipping), implying the importance of early stage PDL compression in the induction of OIRR.

Objectives: To compare posttreatment stability in skeletal Class III patients between those treated by total mandibular arch distalization (TMAD) with buccal mini-implants and those by mandibular setback surgery (MSS).

Materials and methods: The samples included 40 Class III adults, 20 treated by TMAD using buccal interradicular mini-implants and 20 treated with MSS. Lateral cephalograms were taken at pretreatment, posttreatment, and at least 1-year follow-up, and 24 variables were compared using statistical analysis.

Results: Mandibular first molars moved distally 1.9 mm with intrusion of 1.1 mm after treatment in the TMAD group. The mandibular incisors moved distally by 2.3 mm. The MSS group exhibited a significant skeletal change of the mandible, whereas the TMAD group did not. During retention, there were no skeletal or dental changes other than 0.6 mm labial movement of the mandibular incisors (P < .05) in the MSS group. There was 1.4° of mesial tipping (P < .01) and 0.4 mm of mesial movement of the mandibular molars and 1.9° of labial tipping (P < .001) and 0.8 mm of mesial movement of the mandibular incisors in the TMAD group. These dental changes were not significantly different between the two groups.

Conclusions: The TMAD group showed a slightly decreased overjet with labial tipping of the mandibular incisors and mesial tipping of the first molars during retention. Posttreatment stability of the mandibular dentition was not significantly different between the groups. It can be useful to plan camouflage treatment by TMAD with mini-implants in mild-to-moderate Class III patients.