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Fifty-eight patients (mean age 18.4 years) who had received splint therapy for internal derangement of the temporomandibular joint (TMJ) were examined retrospectively to investigate the efficacy of occlusal reconstruction by orthodontic treatment. The subjects were divided into three groups: 18 patients (mean age 18.6 years) who underwent orthodontic treatment combined with the use of splints (ST group); 27 patients (mean age 18.2 years) who underwent orthodontic treatment without the use of splints (NST group); and 13 patients (mean age 17.9 years) who received only splint therapy for temporomandibular joint disorders (TMD; control group). TMJ sound, pain on movement and restriction of mandibular movement were examined at the initial examination (T1), at the end of the splint therapy for TMD or beginning of orthodontic treatment (T2), at the end of orthodontic treatment (T3), and at recall or 1 year after orthodontic treatment (T4). The following results were found. (1) The percentage of patients with no joint sound at T2 was 20-30 per cent. The percentage of such patients in both the ST and NST groups increased to over 50 per cent at T3, but slightly decreased to 39-50 per cent at T4. There were no significant inter-group differences at any time point. (2) The number of patients who had no pain on movement at T2 was 60-80 per cent. The percentage of such patients in both the ST and NST groups increased to over 90 per cent at T3, but then slightly decreased to 80 per cent at T4. There were no significant inter-group differences at any time point. (3) None of the patients showed restriction of movement of the TMJ at T2 or T4. One patient in the ST group was found to have restriction at T3. There were no significant inter-group differences at any time point. (4) The most frequent type of malocclusion in both ST and NST groups was anterior open bite. These results suggest that TMD symptoms that have been eliminated by splint therapy are not likely to recur due to subsequent orthodontic treatment, but it cannot be concluded that orthodontic treatment itself had a positive effect on TMD symptoms. The results also indicate that there is a relationship between anterior open bite and TMD.

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Abstract:Purpose: We have been using myofunctional therapy in orthodontic treatment to improve orofacial disorders. Our previous study showed that lip training increased orbicularis oris muscle strength and endurance. The aim of this study was to determine the effectiveness of hypoxic lip training for improving lip incompetence.Subjects & Methods: Twenty healthy subjects (10 males and 10 females, 23.6 ± 2.3 years old) with lip incompetence participated in this study. We recorded the sealed lip ratio calculated by using the formula "(lip-sealing time / total recorded time) × 100" during relaxation (listening to soothing music) and during concentration (performing a mathematical calculation). Then the subjects performed a standardized hypoxic lip training (5 repetitive contractions with 80% of maximum tensile strength of the orbicularis oris muscle) with a traction plate. Training was repeated daily for 4 weeks. To estimate training effects, the sealed lip ratios during relaxation and concentration were recorded before training (T1), at 2 weeks (T2) and 4 weeks (T3) after the start of training, and at 4 weeks (T4) and 8 weeks (T5) after the end of training.Results: The sealed lip ratios in both the relaxation and concentration conditions significantly (P < 0.003 after Bonferroni correction) increased during the training period. Although the sealed lip ratios slightly decreased during the post-training period, they were not significantly different from those at T3.Conclusions: Hypoxic lip training increases the sealed lip ratio and is thus effective for improving lip incompetence. Sealed lip ratios were maintained after 8 weeks of training.