Maxillary central incisor impaction is one of the most common types of dental anomalies in children. Treatment of impacted central incisors is complicated and challenging given the position of the impacted central incisors, root development, and the complexity of the crown eruption direction. This study aimed to describe the use of a new multifunctional appliance for the treatment of impacted maxillary central incisors. This article reports the use of a novel appliance for the treatment of impacted maxillary central incisors. We describe the cases of two young patients with labial horizontally impacted maxillary central incisors. Both patients were treated using this novel appliance. Therapeutic effects were evaluated by comparing the pretreatment results, posttreatment cone-beam computed tomography images, and posttreatment clinical examination results. At the end of the treatment period using the novel appliance, the impacted central incisors had successfully been properly aligned in the dental arch, and the tooth roots had not resorbed. Both patients exhibited good dental alignment, with restored function and acceptable aesthetics. This article demonstrates that the new appliance was comfortable, convenient, safe, and effective in the treatment of impacted maxillary central incisors and that its clinical use should be promoted in the future.

Catathrenia is a rare disease, classified as isolated symptoms and normal variants under sleep-related breathing disorders in the International Classification of Sleep Disorders, third edition. Because of its rarity, the research on its pathogenesis and treatment is insufficient. This study aimed to evaluate whether the mandibular advancement device (MAD) could be considered an alternative treatment trial and if so, to explore factors predicting its effectiveness.
Thirty patients (12 men and 18 women, aged 16-67 years) with catathrenia participated in the study. They underwent standard clinical evaluation, questionnaires, physical examinations, craniofacial evaluations, video polysomnography, and imaging of the upper airway before and after the insertion of the MAD. The groaning index (groaning episodes per hour of sleep) and apnea-hypopnea index were evaluated, and anatomic factors predicting effectiveness were explored.
The sleep efficiency of most patients was higher than 80%, and groaning was present throughout all stages of sleep. With the insertion of the MAD, the groaning index decreased significantly from 5.8 (2.7-14.3) to 2.8 (1.3-12.2) events/h (P = .014). Age had a negative effect on efficacy. Mandibular repositioning of the MAD, especially the amount of vertical opening and changes of the cross-sectional area of the hypopharynx, was positively related with efficacy.
The MAD could be considered a possible treatment trial for those seeking treatment for groaning.
Registry: Chinese Clinical Trial Register; Name: The etiology of catathrenia based on oral and maxillofacial system; URL: http://www.chictr.org.cn/showproj.aspx?proj=22286; Identifier: ChiCTR-COC-17013239.
Yu M, Hao Z, Xu L, Wen Y, Han F, Gao X. Mandibular advancement device as treatment trial for catathrenia (nocturnal groaning). J Clin Sleep Med. 2021;17(9):1767-1776.

Obstructive sleep apnea (OSA), a common sleep disorder disease, affects millions of people. Without appropriate treatment, this disease can provoke several health-related risks including stroke and sudden death. A variety of treatments have been introduced to relieve OSA. The main present clinical treatments and undertaken research activities to improve the success rate of OSA were covered in this paper. Additionally, guidelines on choosing a suitable treatment based on scientific evidence and objective comparison were provided. This review paper specifically elaborated the clinically offered managements as well as the research activities to better treat OSA. We analyzed the methodology of each diagnostic and treatment method, the success rate, and the economic burden on the world. This review paper provided an evidence-based comparison of each treatment to guide patients and physicians, but there are some limitations that would affect the comparison result. Future research should consider the consistent follow-up period and a sufficient number of samples. With the development of implantable medical devices, hypoglossal nerve stimulation systems will be designed to be smart and miniature and one of the potential upcoming research topics. The transcutaneous electrical stimulation as a non-invasive potential treatment would be further investigated in a clinical setting. Meanwhile, no treatment can cure OSA due to the complicated etiology. To maximize the treatment success of OSA, a multidisciplinary and integrated management would be considered in the future.

OBJECTIVE: To analyze the morphological changes in the upper airway of obstructive sleep apnea syndrome (OSAS) patients treated with oral appliance in skeletal class Ⅱ malocclusion with different vertical features by using cone beam CT (CBCT).
METHODS: Thirty-six patients diagnosed with OSAS by polysomnography and daytime sleepiness scale and skeletal class Ⅱ malocclusion were treated with oral appliance for 4 months. The changes based on CBCT in the morphology of glossopharyngeal and palatopharyngeal before and after treatment in OSAS patients with different vertical features were compared.
RESULTS: After treatment with oral appliance, the glossopharyngeal and palatopharyngeal morphologies of patients with mild OSAS showed significant changes. After treatment with oral appliance, the glossopharyngeal morphology of all patients showed significant changes (P<0.05). The palatopharyngeal morphology of patients in the lower and average groups also exhibited significant changes (P<0.05). Sagittal changes in the glossopharyngeal measurements of high-angle patients demonstrated significant difference, whereas the other measured values showed no significant difference.
CONCLUSIONS: The morphological changes in the upper airway were significant in OSAS patients with lower and average vertical patterns when treated with oral appliance, but the changes in high vertical patterns were not significant.
目的 通过锥形束CT（CBCT）影像比较研究口腔矫治器治疗不同垂直骨面型的骨性Ⅱ类错牙合畸形伴阻塞性睡眠呼吸暂停综合征（OSAS）患者前后上气道三维形态变化。方法 采用口腔矫治器对多导睡眠监测仪及白天嗜睡量表诊断为OSAS且为骨性Ⅱ类错牙合畸形的36例患者进行治疗，戴用矫治器治疗4个月后，进行CBCT扫描分析不同垂直骨面型的OSAS患者治疗前后腭咽、舌咽等不同部位上气道形态的三维改变。结果 与治疗前相比，在戴用可调式矫治器4个月时，所有患者的腭咽容积测量值均显著增加（P<0.05）；低角和均角患者的舌咽各项测量值均显著提高（P<0.05），高角患者的舌咽测量值中仅矢状向变化有显著差异，其余测量值变化的差异无统计学意义。结论 口腔治疗器治疗下颌后缩的OSAS患者时，能显著改善低角患者和均角患者的上气道形态，但高角患者的上气道形态变化不大。.

To analyze the effect of gradual increments of mandibular advancement on the treatment efficacy of mandibular advancement devices and identify determinants of effective and target protrusion for OSA.
Patients were prospectively recruited. The mandible was titrated from 0 mm with a stepwise increment of 0.5 mm until the AHI was reduced to the lowest level. Rhinospirometry, rhinomanometry, and magnetic resonance imaging were used to observe the change of respiratory function and upper airway morphology.
Forty-two patients aged 41.5 ± 9.0 years participated. There was a dose-dependent relationship between mandibular protrusion and the AHI improvement rate, the success rate, and the normalization rate; the changing curves plateaued after approximately 70% of maximal mandibular protrusion was achieved. The correlation between AHI and mandibular protrusion became stronger as the severity of OSA increased. The target protrusion for patients with mild, moderate, and severe OSA was 3.5 ± 1.8 mm (38.6 ± 19.4% maximal mandibular protrusion), 5.8 ± 1.9 mm (62.9 ± 18.8% maximal mandibular protrusion), and 5.9 ± 2.2 mm (68.8 ± 15.6% maximal mandibular protrusion), respectively. Regression analysis revealed that the factors influencing effective and target protrusion included change of maximal lateral dimension of the total upper airway with mandibular advancement devices, mean lateral dimension of the oropharynx, and soft palate length. Further protrusion brought more lateral expansion of the velopharynx, whereas the change in nasal ventilation was not significant.
The dose-dependent effect of mandibular protrusion on reduction of AHI by mandibular advancement devices was nonlinear and became more pronounced with increased severity of OSA. The mandibular protrusion should be more personalized to each patient.
Registry: Chinese Clinical Trial Registry; Name: Study of the Onset Point of Oral Appliance Treatment in Obstructive Sleep Apnea and Hypopnea Syndrome; URL: http://www.chictr.org.cn/showproj.aspx?proj=22291; Identifier: ChiCTR-IND-17013232.

Objective: The severity of obstructive sleep apnea hypopnea syndrome (OSAHS) has a tendency to increase with age. The purpose of this study was to explore whether oral appliance (OA) treatment can block this age-related change. Methods: This study was a retrospective study. Fifteen patients (12 males,3 females) of OSAHS treated with OA were selected as treatment group,with an average age of (47.44±10.00) years and initial body mass index (BMI) of (26.31±3.33) kg/m(2). The follow-up length was 54 [22, 100] months. Nineteen patients (13 males,6 females) with untreated OSAHS served as controls, with an average age of (45.00±9.26) years and initial BMI of (25.53±2.58) kg/m(2),and the follow-up length was 35 [26,63] months. There were no significant differences in terms of gender,age,initial BMI, apnea hypopnea index(AHI), and follow-up length between the two groups. Polysomnography(PSG) data for the two groups were compared to observe the sleep respiratory function changes as aging by Wilcoxon test. Results: There was no significant difference in BMI of the treatment group and the control group at the time of follow-up, with BMI of treatment group from (26.31±3.33) kg/m(2) to (25.67±3.65) kg/m(2),Z=-1.223,P=0.221; and BMI of control group from (25.53±2.58) kg/m(2) to (25.12±2.72) kg/m(2),Z=-1.193,P=0.233. There was no significant difference in the change of AHI within the treatment group, from 26.20 [11.50, 52.98]/h to 23.10 [16.00, 45.00]/h, Z=-0.284, P=0.776; AHI in the control group was higher than that at the first visit, and the AHI increased from 15.00 [10.72, 28.90]/h to 31.10 [13.00, 41.80]/h, Z=-3.481, P<0.001. The longest apnea duration was not statistically different in the treatment group, from 60.00 [56.40, 74.00] s to 63.00 [52.00, 77.00] s, Z=-0.345, P=0.730; the longest apnea duration in the control group increased from 42.00 [34.00, 56.70] s to 46.00 [37.00,62.00] s,Z=-2.274,P=0.023. There was no significant difference in the lowest blood oxygen saturation of the treatment group and the control group, with the treatment group from 72.47%±12.69% to 72.73%±17.59%, Z=-0.597, P=0.550; and the control group from 78.21%±9.30% to 76.42%±12.17%, Z=-0.153, P=0.879. Conclusion: Symptoms of sleep apnea in OSAHS patients tend to increase with age,and oral appliance treatment may have the effect of slowing down this age-related worsening effect.
目的： 探索口腔矫治器（oral appliance，OA）治疗能否减缓阻塞性睡眠呼吸暂停低通气综合征（OSAHS）患者的增龄性改变。 方法： 本研究为回顾性研究，筛选出1995—2005年在北京大学口腔医学院正畸科接诊的15例（12男，3女）使用OA治疗的OSAHS患者作为治疗组，平均年龄（47.44±10.00）岁，初始体质量指数（BMI）为（26.31±3.33）kg/m(2)，复诊间隔54[22，100]个月。筛选19例（13男，6女）未经治疗的OSAHS患者作为对照组，平均年龄（45.00±9.26）岁，初始BMI（25.53±2.58）kg/m(2)，复诊间隔35[26，63]个月。两组患者在性别、年龄、初始BMI、呼吸暂停低通气指数（apnea hypopnea index，AHI）及复诊间隔差异无统计学意义。对两组患者整夜多道睡眠监测（PSG）资料进行比较，通过秩和检验（Wilcoxon配对法）观察两组患者睡眠呼吸功能随年龄变化的情况。 结果： 复诊时，治疗组及对照组BMI差异均无统计学意义[治疗组：（26.31±3.33）kg/m(2)比（25.67±3.65）kg/m(2)，Z=-1.223，P=0.221；对照组：（25.53±2.58）kg/m(2)比（25.12±2.72）kg/m(2)，Z=-1.193，P=0.233]。治疗组AHI变化差异无统计学意义（26.20[11.50，52.98]次/h比23.10[16.00，45.00]次/h，Z=-0.284，P=0.776）；对照组AHI复诊时较初诊时升高（15.00[10.72，28.90]次/h比31.10[13.00，41.80]次/h，Z=-3.481，P<0.001）。最长呼吸暂停时间，治疗组差异无统计学意义（60.00[56.40，74.00]s比63.00[52.00，77.00]s，Z=-0.345，P=0.730）；对照组较初诊时升高（42.00[34.00，56.70]s比46.00[37.00，62.00]s，Z=-2.274，P=0.023）。最低动脉血氧饱和度在治疗组及对照组前后差异均无统计学意义（治疗组：72.47%±12.69%比72.73%±17.59%，Z=-0.597，P=0.550；对照组：78.21%±9.30%比76.42%±12.17%，Z=-0.153，P=0.879）。 结论： OSAHS患者睡眠呼吸暂停症状有随年龄增大而加重的趋势，口腔矫治器治疗可能具有减缓这种增龄性恶化的作用。.

Objective:To investigate the effect of adjustable oral appliance on airway changes and clinical effect in obstructive sleepApnea hypopnea syndrome,and to observe the effect of jaw joints.Method:Forty adult cases diagnosed as OSAHS by polysomnography(PSG), were treated with adjustable oral appliance.After six months,the sleep apnea hypoventilation index(AHI)and the lowest oxygen saturation (LSaO₂) by PSG were evaluated. And three-dimensional cone beam computed tomography(CBCT) reconstruction was used to analyze the morphological changes of the upper airway,and the gap of jaw joint preliminarily.Result:After such treatment, LSaO₂ level of all cases increased, and AHI reduced(P< 0.01).The total volume and area of the upper airway increased significantly(P< 0.01), There was no obvious anomalies found in jaw joints.Conclusion:The adjustable oral appliance applied to in adult OSAHS can increase the shape and size of the airway,improve the airway ventilation effectively, and have no affection to the jaw joints in initial observation.

Objective: To update the meta-analysis comparing the effectiveness of oral appliance (OA) with continuous positive airway pressure (CPAP) in treating patients with obstructive sleep apnea (OSA). Methods: PubMed, ISI Web of Knowledge, Ovid, EBSCO Dentistry & Oral Science Source, The Cochrane Library, and Embase database were searched for RCTs until 23 May 2017. Meta-analyses were performed using RevMan 5.3. Results: Sixteen RCTs were included. Compared with OA, CPAP significantly decreased AHI, min SaO2, ARI, ESS (p < 0.05), with no significant difference in REM%, FOSQ, BP (p ≥ 0.05). OA significantly improved REM% in the severe groups and ESS in the adjustable OA group (p < 0.05). OA shared greater preference. Conclusion: Even though CPAP can better decrease the severity of OSA, more patients opted for OA, which showed better results in severe patients, especially adjustable OA.

We report about a novel imaging technique for airflow analysis, particle image velocimetry (PIV), used in a moderate obstructive sleep apnea (OSA) patient. By measuring the airflow characteristics in the upper airway at different protrusion positions, the effect of mandibular advancement device (MAD) on OSA was further understood.

Oral appliance (OA) can effectively treat obstructive sleep apnea; however, numerous types of oral appliances and designs are variable and the precise mechanisms behind differences in treatment outcomes are uncertain. The objective of this study was to evaluate the effects of different degrees of mandibular position [4° of bite openings (BO): 2, 4, 8 and 12 mm; and protrusion (P): 0, 50%, MAX], for both the upright and supine positions: BO2 mm_P0%, BO4 mm_P0%, BO4 mm_P50%, BO4 mm_PMAX, BO8 mm_P0%, BO12 mm_P0%; with an OA on the: (1) activity of the genioglossus (GG) muscle by electromyogram, (2) inspiration by airflow sensor, and (3) recording mandibular movements (incisor and mandibular condyle point) in each position. Nine healthy male adults (age 27.5 ± 1.30 years) were recruited. The results show that GG muscle activity increased significantly from BO 4 mm_P0% to BO12 mm_P0% during the supine position, and the strongest signal was found in BO4 mm_PMAX, compared to all of the other positions, and GG muscle activity in BO4 mm_P0% tended to be lower. From supine to upright position the inspiration increased significantly but GG muscle activity did not. These results might be a stimulus to augment a compensatory mechanism of GG muscle induced by OA, however, mainly in protrusion position. The increase of BO (2-12 mm) and even maximum protrusion might not negatively affect the temporomandibular joint.