Kinematics ofmandibular advancement devices(MADs):Why do some MADs move the lower jaw backward duringmouth opening?

Mandibular advancement devices(MADs)are widely used treatments for obstructive sleep apnea.MADs function by advancing the lower jaw to open the upper airway.To increase patient comfort,most patients allow the mouth to be opened.However,not all systems maintain the lower jaw in a forward position during mouth opening,which results in the production of a retrusion that favors the collapse of the upper airway.Furthermore,the kinematic behavior of the mechanism formed by the mandible-device assembly depends on jaw morphology.This means that,during mouth opening,some devices cause lower jaw protrusion in some patients,but cause its retraction in others.In this study,we report the behavior of well-known devices currently on themarket.To do so,we developed a kinematic model of the lower jawdevice assembly.Thismodelwas validated for all devices analyzed using a high-resolution camera system.Our results show that some of the devices analyzed here did not produce the correct behavior during patient mouth opening.

3D kinematicmandiblemodel to designmandibular advancement devices for the treatment of obstructive sleep apnea

Mandibular advancement devices(MADs)are one of the treatments used for Obstructive sleep apnea(OSA).MADs try to maintain the mandible in an advanced position to keep the upper airways open when sleeping.To achieve this goal,most current MADs limit the mouth opening to a few millimetres.The study of the kinematic behaviour of the patient’s jaw is essential in order to design devices that allow greater aperture ranges.For this purpose,a 3D multibody model that reproduces jaw movement has been developed in this work.To this end,the movement of the lower incisor has been determined by means of a vision system and reflective markers.In addition,the kinematics of the temporomandibular joint has been modelled.Next,the device is designed and printed using a cam-follower mechanism.This way,the cam profiles and the followers are optimally designed and positioned for each patient depending on the physiognomy of the jaw and the opening and advancing movement prescribed by the specialist.

Analysis of Referrals for Mandibular Advancement Appliances for Sleep Apnoea

Aim: This article investigates the increasing awareness of Obstructive Sleep Apnoea (OSA) as a potentially serious health risk and highlights the role of the dentist in managing mild to moderate OSA cases which can be improved with an intra-oral mandibular advancement appliance. Methods: Data from referrals to a Prosthodontic Unit from 01-01-2019 to 18-8-2022 were analysed. Results: A total of 240 consecutive referrals to an NHS hospital where a patient was fitted with a mandibular advancement appliance (MAA) were analysed and 160 (67%) were male and 80 (33%) were female. The mean age in years was 52 (2019), 50 (2020), 52 (2021) and 51 (2022). Mean age of male referrals was 51 and female referrals was 53. Conclusion: There are a large number of patients with OSA seeking a dental device and practitioners should be aware of this treatment modality to help the medical team manage OSA. Clinical relevance: Dentists may need to have a greater understanding of OSA and be able to provide MAAs.

Efficacy of invisible advancement correction for mandibular retraction in adolescents based on Pancherz analysis

BACKGROUND Mandibular retraction is the main etiological mechanism of class II malocclusion in China and the subsequent distal molar relationship can cause functional discomfort in mastication,breathing and the temporomandibular joint.The use of mandibular advancement(MA)devices has recently emerged as an adolescent mandibular retraction treatment;however,current studies regarding the effect thereof are relatively few,and there is lack of sufficient clinical support.AIM To investigate the clinical effect of invisalign MA on the treatment of mandibular retraction in adolescents.METHODS This study included 30 adolescent patients who underwent treatment with the MA appliances from December 2017 to June 2021.The lateral cephalometric data before and after treatment were collected and imported into Dolphin Imaging software.The changes were measured by linear measurement superimposed with lateral cephalometric trajectory based on the Pancherz technology.RESULTS There was no significant difference in the length and position of maxilla before and after the treatment.The position of the mandible moved 3.13 mm,the length increased 4.14 mm,the mandibular ramus length increased 4.09 mm,the body length increased 4.25 mm,and the position of the condyle moved 1.03 mm forward after treatment.Additionally,changes in the incisor sagittal position and labial inclination were observed.The position of the upper incisor point moved back 1.33 mm,without statistical difference,the inclination and tooth angle decreased by 3.44°and 4.06°,respectively;the position of the lower incisor point was moved 2.98 mm,and the inclination and tooth angle increased by 2.62°and 1.23°,respectively.Furthermore,changes in the incisor overjet and molar relationship were seen.Overjet decreased by 4.31 mm,of which 1.78 mm was due to dental factors,accounting for 41.3%of the effect as opposed to 58.7%due to skeletal factors.Molar relationship improved 3.87 mm,with 1.34 mm due to dental factors,and dental and skeletal factors were accounted for 34.6%and 65.4%of the effect,respectively.CONCLUSION For adolescent patients with mandible retraction,invisalign MA can effectively promote the mandible growth,and it was proven to be mainly due to skeletal effects.

Hybrid treatment of varied orthodontic appliances for a patient with skeletal class II and temporomandibular joint disorders:A case report and review of literature

BACKGROUND The relation between orthodontic treatment and temporomandibular disorders(TMDs)is under debate;the management of TMD during orthodontic treatment has always been a challenge.If TMD symptoms occur during orthodontic treatment,an immediate pause of orthodontic adjustments is recommended;the treatment can resume when the symptoms are managed and stabilized.CASE SUMMARY This case report presents a patient(26-year-old,female)with angle class I,skeletal class II and TMDs.The treatment was a hybrid of clear aligners,fixed appliances and temporary anchorage devices(TADs).After 3 mo resting and treatment on her TMD,the patient’s TMD symptom alleviated,but her anterior occlusion displayed deep overbite.Therefore,the fixed appliances with TAD were used to correct the anterior deep-bite and level maxillary and mandibular deep curves.After the levelling,the patient showed dual bite with centric relation and maximum intercuspation discrepancy on her occlusion.After careful examination of temporomandibular joints(TMJ)position,the stable bite splint and Invisible Mandibular Advancement appliance were used to reconstruct her occlusion.Eventually,the improved facial appearance and relatively stable occlusion were achieved.The 1-year follow-up records showed there was no obvious change in TMJ morphology,and her occlusion was stable.CONCLUSION TMD screening and monitoring is of great clinical importance in the TMD susceptible patients.Hybrid treatment with clear aligners and fixed appliances and TADs is an effective treatment modality for the complex cases.

Successful Treatment of Postpeak Stage Patients with ClassⅡ Division 1 Malocclusion Using Non-extraction and Multiloop Edgewise Archwire Therapy: A Report on 16 Cases

Aim To determine cephalometrically the mechanism of the treatment effects of non-extraction and multiloop edgewise archwire （MEAW） technique on postpeak Class Ⅱ Division 1 patients. Methodology In this retrospective study, 16 postpeak Class Ⅱ Division 1 patients successfully corrected using a non-extraction and MEAW technique were cephalometrically evaluated and compared with 16 matched control subjects treated using an extraction technique. Using CorelDRAW software, standardized digital cephalograms preand post-active treatments were traced and a reference grid was set up. The superimpositions were based on the cranial base, the mandibular and the maxilla regions,and skeletal and dental changes were measured. Changes following treatment were evaluated using the paired-sample t-test. Student＇s t-test for unpaired samples was used to assess the differences in changes between the MEAW and the extraction control groups. Results The correction of the molar relationships comprised 54% skeletal change （mainly the advancement of the mandible） and 46% dental change. Correction of the anterior teeth relationships comprised 30% skeletal change and 70% dental change. Conclusion The MEAW technique can produce the desired vertical and sagittal movement of the tooth segment and then effectively stimulate mandibular advancement by utilizing the residual growth potential of the condyle.

Changes in sleep parameters following biomimetic oral appliance therapy: A case report

BACKGROUND Mandibular advancement devices(MADs)are used to treat mild to moderate obstructive sleep apnea(OSA),but there is a risk that the underlying condition can worsen in the long-term.Therefore,this case report is based on biomimetic oral appliance therapy as an alternative to MADs,which was found to be beneficial in the treatment of a case with severe OSA.CASE SUMMARY An overnight sleep study was undertaken in a 50-year-old male with excessive daytime sleepiness that lead to a diagnosis of severe OSA as the apnea-hypopnea index(AHI)was found to be 32.8/h.Since the patient was unable to comply with continuous positive airway pressure therapy and declined surgical intervention,treatment with a MAD was initiated.Approximately 10 years later,another sleep study was performed with no MAD in the mouth,which revealed an AHI of 67.9/h.In view of the deterioration in sleep quality,the patient sought alternative treatment and elected on biomimetic oral appliance therapy,using a mandibular repositioning nighttime appliance(mRNA appliance®,Vivos Therapeutics,Inc.,United States).After 10 mo,another sleep study was performed with no device in the patient’s mouth,which revealed an AHI of 11.8/h,a mean oxygen saturation of 94%and a mean oxygen desaturation index of 5.3%while sleeping.Finiteelement analysis of the pre-and post-treatment study models of the upper jaw showed localized size increases of 15%-17%in the premolar regions and 15%-23%in the molar regions.CONCLUSION In adults with severe OSA that are unable to accept continuous positive airway pressure or surgical treatment,biomimetic oral appliance therapy may be preferable over MADs since biomimetic oral appliance therapy may be able to prevent worsening of sleep parameters by remodeling the nasomaxillary complex.Long-term follow up studies are required to verify these novel findings.

Clinical consequences and economic costs of untreated obstructive sleep apnea syndrome

Objective: To provide an overview of the healthcare and societal consequences and costs of untreated obstructive sleep apnea syndrome.Data sources: PubMed database for English-language studies with no start date restrictions and with an end date of September 2014.Methods: A comprehensive literature review was performed to identify all studies that discussed the physiologic, clinical and societal consequences of obstructive sleep apnea syndrome as well as the costs associated with these consequences.There were 106 studies that formed the basis of this analysis.Conclusions: Undiagnosed and untreated obstructive sleep apnea syndrome can lead to abnormal physiology that can have serious implications including increased cardiovascular disease, stroke, metabolic disease, excessive daytime sleepiness, work-place errors, traffic accidents and death.These consequences result in significant economic burden.Both, the health and societal consequences and their costs can be decreased with identification and treatment of sleep apnea.Implications for practice: Treatment of obstructive sleep apnea syndrome, despite its consequences, is limited by lack of diagnosis, poor patient acceptance, lack of access to effective therapies, and lack of a variety of effective therapies.Newer modes of therapy that are effective, cost efficient and more accepted by patients need to be developed.