Indications for Dental Specialists for Treating Obstructive Sleep Apnea with Mandibular Advancement Devices: A Narrative Review.

Obstructive sleep apnea (OSA) syndrome is characterized by repeated airway collapse during sleep. It determines cardiovascular, pulmonary, and neurocognitive consequences and is associated with several daytime and nighttime symptoms that influence the patient's quality of life. The contribution of the dental specialist in the clinical management of OSA patients entails participating in the screening process as diagnostic sentinels and providing adequate treatment using mandibular advancement devices (MADs). Since the treatment of OSA requires a multidisciplinary approach, including different medical specialists, dentists should have a comprehensive understanding of medical and dental factors that influence the strategy and effectiveness of OSA treatment with MAD. Such expertise is crucial in determining the appropriate treatment indications and helps clinicians establish a consolidated position within the multidisciplinary OSA team. In this regard, this review summarizes the evidence of the clinical indications for MAD treatment and provides the dental specialist with helpful information about medical, functional, and other relevant factors that should be considered during diagnosis, treatment plan, and follow-up stages. Information retrieved was organized and discussed, generating specific domains/queries oriented to the clinical management of OSA patients from the clinical perspective of dental specialists.

Medium-term effects of rapid maxillary expansion on nasal cavity and pharyngeal airway volumes considering age as a factor: A retrospective study.

OBJECTIVES: The medium-term effects of rapid maxillary expansion (RME) on nasal cavity (NC) and upper airway (UA) dimensions based on chronological age are still unclear. This retrospective study evaluated the medium-term changes occurring in the NC and pharyngeal airways (PA) after RME in two distinct age-based cohorts of patients. METHODS: This retrospective study included 48 subjects who underwent RME grouped in two cohorts: a 6-9-year-old group (EEG group: early expansion group - 25 subjects) and an 11-14-year-old group (LEG group: late expansion group - 23 subjects). NC and PA volumes were analyzed from CBCT imaging segmentation before RME (T0) and twelve months after RME (T1). The amount of maxillary expansion (PW) and minimal cross-sectional area (CSmin) were also considered. RESULTS: All PAs' volumetric sub-regions, CSmin and PW showed a significant volumetric increment (p < 0.05). Inter-group comparisons showed significant differences (p < 0.05) for nasopharynx and CSmin parameters (p < 0.05), while no significant changes were recorded for the other UA's sub-regions and PW (p > 0.05). According to a deviation analysis, part of the UA increase (more marked for the nasopharynx area) may have occurred due to reduced adenotonsillar tissues, which were larger in the EEG group. CONCLUSIONS: Twelve months after treatment, clinicians should not expect changes in the UAs dimensions to be solely related to treatment effects of RME; instead, normal craniofacial growth changes and spontaneous regression of the adenotonsillar tissue could represent the most significant factors influencing UAs changes. CLINICAL SIGNIFICANCE: From the clinical perspective, the results of the present study encourage caution when considering the therapeutic effects of RME on airways dimensions.

Awareness and Sources of Knowledge about Obstructive Sleep Apnea: A Cross Sectional Survey Study.

Obstructive sleep apnea (OSA) is a multifactorial sleep breathing disorder, seriously impacting quality of life and involving approximately 1 billion of the world's population. It is characterized by episodes of total cessation of breathing or decreases in airflow during sleep. Available data suggest that most cases of OSA remain undiagnosed even in developed countries. This is due to a lack of widespread knowledge about this pathology and the medical morbidities and mortality it brings about, among both laypeople and physicians. Moreover, despite receiving indications about the need to undergo specific evaluations for OSA signs and symptoms, sometimes patients do not pay sufficient attention to the problem. This is probably due to a lack of correct information on these issues. The present investigation analyzed the level of knowledge about OSA pathology and the sources through which a group of OSA patients gained information on their condition. A survey of 92 patients diagnosed with OSA (mean age 60.55 ± 10.10) and referred to the Unit of Orthodontics and Dental Sleep Medicine of the University of Bologna was conducted by means of a questionnaire investigating sociodemographic characteristics, the level of general knowledge on OSA pathology and its possible medical consequences. Despite about two third (67.38%) of the population demonstrating extensive knowledge, remarkably, a group of subjects (20.65%) had poor awareness of the OSA condition. A statistically significant correlation emerged between the level of knowledge about OSA and the level of education (p = 0.002). A great effort should be made to improve the quality of information and the communication modalities for OSA to enable a fully appropriate awareness of the condition among patients.

Response to letter to the Editor: Look at the elephant! Commentary on 'Prevalence of temporomandibular disorders in adult obstructive sleep apnoea patients: A cross-sectional controlled study'.

Obstructive sleep apnoea and temporomandibular disorders are complex pathologies. Considering dento-skeletal occlusion as their main predisposing factor could be detrimental for optimal patient care.

The Effect of Bite Raise on AHI Values in Adult Patients Affected by OSA: A Systematic Review with Meta-Regression.

Obstructive sleep apnea (OSA) is a highly prevalent sleep breathing disorder characterized by the collapse of the pharyngeal walls that entails recurrent episodes of cessation of breathing or decrease in airflow while sleeping. This results in sleep fragmentation, decreased oxygen saturation and an increase in the partial pressure of carbon dioxide, causing excessive daytime sleepiness, hypertension and increased prevalence of cardiovascular morbidity and mortality. Mandibular advancement devices (MAD) represent a valid alternative therapy to Continuous Positive Airway Pressure, thrusting the mandible forward, increasing the lateral diameter of the pharynx and reducing the collapsibility of the airway. Several investigations have focused on the detection of the best mandibular advancement amount in terms of effectiveness and tolerance, but few and contrasting data are available on the role of occlusal bite raise in reducing the apnea/hypopnea index (AHI). The aim of this systematic review with meta-regression analysis was to investigate the effect of the bite raise of MAD on AHI values in adult patients affected by OSA. An electronic search was performed in MEDLINE, the Cochrane Database, Scopus, Web of Science and LILACS. Randomized controlled trials (RCT) investigating the effectiveness of MAD in OSA patients were included. The quality of evidence was evaluated with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) and the risk of bias with the Cochrane risk-of-bias tool for randomized trials (RoB2). Six RCT were included. The success rate of each study was computed: (mean baseline AHI - mean post treatment AHI)/mean baseline AHI. The GRADE scores indicated that the quality of evidence was very low. The meta-regression analysis showed that there was no correlation between the occlusal bite raise and the AHI improvement.

Sleep Bruxism and Orofacial Pain in Patients with Sleep Disorders: A Controlled Cohort Study.

BACKGROUND: The gold standard for the diagnosis of sleep bruxism (SB) is laboratory polysomnography (L-PSG) recording. However, many clinicians still define SB using patients' self-assessment and/or clinical tooth wear (TW). The purpose of this cross-sectional controlled study was to compare the prevalence of TW, head-neck muscles sensitivity and Temporomandibular Disorders (TMD) between SB and non-SB patients diagnosed with L-PSG in a cohort of patient with sleep disorders (SD). METHODS: 102 adult subjects with suspected SD underwent L-PSG recording to assess the presence of sleep disorder and SB. TW was clinically analyzed using TWES 2.0. The pressure pain threshold (PPT) of masticatory muscles were assessed using a Fisher algometer. Diagnostic criteria for TMD (DC/TMD) were used to evaluate the presence of TMD. SB self-assessment questionnaires were administered. TWES score, PPT, TMD prevalence and questionnaire results were compared between SB and non-SB patients. RESULTS: 22 SB patients and 66 non-SB patients with SD were included. No significant differences emerged between groups in regards to TW, the PPT values, or SB's self-assessment questionnaires as well the prevalence of TMD. CONCLUSION: in a SD population, TW is not pathognomonic of active SB and SB self-assessment is not reliable. There seems to be no correlation between SB, TMD and head/neck muscle sensitivity.

Antero-Posterior Mandibular Excursion in Obstructive Sleep Apnea Patients Treated with Mandibular Advancement Device: A Retrospective Cohort Study.

Since obstructive sleep apnea (OSA) management with a mandibular advancement device (MAD) is likely to be life-long, potential changes in mandibular movements during therapy should be investigated. The purpose of this study was to use a method that has already been shown to be reliable in order to determine whether the range of antero-posterior mandibular excursion, the procedure upon which MAD titration is based, varies between baseline (T0) and at least 1 year of treatment (T1). The distance between maximal voluntary protrusion and maximal voluntary retrusion determined using the millimetric scale of the George Gauge was retrospectively collected from the medical records of 59 OSA patients treated with the MAD and compared between T0 and T1. A regression analysis was performed to evaluate the influence of treatment time, MAD therapeutic advancement and the patient's initial characteristics in excursion range variation. A statistically significant increase of 0.80 ± 1.52 mm (mean ± standard deviation, p < 0.001) was found for antero-posterior mandibular excursion. The longer the treatment time (p = 0.044) and the smaller the patient's mandibular excursion at T0 (p = 0.002), the greater the increase was. These findings could be explained by a muscle-tendon unit adaptation to the forward mandibular repositioning induced by the MAD. During MAD therapy, patients can develop a wider range of antero-posterior mandibular excursion, especially those with a smaller initial excursion capacity.

Prevalence of temporomandibular disorders in adult obstructive sleep apnoea patients: A cross-sectional controlled study.

BACKGROUND: Obstructive sleep apnoea (OSA) is characterised by partial or complete obstruction of the upper airways during sleep and it has been associated with temporomandibular disorders (TMDs) on the basis of several pathophysiological hypotheses. OBJECTIVES: To assess the prevalence of TMDs in a population of patients affected by OSA compared to a control group of subjects not affected by OSA. METHODS: A cross-sectional controlled study was conducted on a group subjects studied by polygraphy (PG) at the snoring section of the ENT department, Sant'Orsola-Malpighi Hospital - University of Bologna. Patients who received a diagnosis of OSA were included in the study group and subjects with a negative PG diagnosis for Sleep Disordered Breathing and PG respiratory pattern that did not suggest the occurrence of sleep disorders were enrolled in the control group. Both the subjects included in the study group and the control group underwent an examination following the Diagnostic Criteria for Temporomandibular Disorders Axis I and II. RESULTS: Forty-three OSA patients (29 M, 16 F, mean age 52.26 ± 11.40) and 43 healthy controls (25 M, 18 F, mean age 49.95 ± 7.59) were included in the study. No significant differences were found between groups in demographic data. TMD prevalence and Axis II results did not differ between groups. CONCLUSIONS: This paper does not highlight a higher prevalence of TMDs in adults with OSA compared to healthy controls. Further high-quality studies are needed to confirm the results and to give possible pathophysiological explanations, providing reliable evidence.

Effect of orthopedic and functional orthodontic treatment in children with obstructive sleep apnea: A systematic review and meta-analysis.

Orthodontic treatment is suggested in growing individuals to correct transverse maxillary deficiency and mandibular retrusion. Since, as a secondary effect, these orthodontic procedures may improve pediatric obstructive sleep apnea (OSA), this systematic review assessed their effects on apnea-hypopnea index (AHI) and oxygen saturation (SaO2). Twenty-five (25) manuscripts were included for qualitative synthesis, 19 were selected for quantitative synthesis. Five interventions were analyzed: rapid maxillary expansion (RME, 15 studies), mandibular advancement (MAA, five studies), myofunctional therapy (MT, four studies), and RME combined with MAA (one study). RME produced a significant AHI reduction and minimum SaO2 increase immediately after active treatment, at six and 12 months from baseline. A significant AHI reduction was also observed six and 12 months after the beginning of MAA treatment. MT showed positive effects, with different protocols. In this systematic review and meta-analysis of data from mainly uncontrolled studies, interceptive orthodontic treatments showed overall favorable effects on respiratory outcomes in pediatric OSA. However, due to the low to very low level of the body evidence, this treatment cannot be suggested as elective for OSA treatment. An orthodontic indication is needed to support this therapy and a careful monitoring is required to ensure positive improvement in OSA parameters.

Online information on mandibular advancement device for the treatment of obstructive sleep apnea: A content, quality and readability analysis.

BACKGROUND: Despite increasing scientific interest in the effectiveness of mandibular advancement device (MAD) for the treatment of obstructive sleep apnoea (OSA), laypeople lack knowledge about this treatment option. OBJECTIVES: To investigate content, quality and readability of the online information regarding MAD. METHODS: Google, Yahoo and Bing were searched for 'sleep apnea', 'mandibular advancement device' and 'oral appliance'. Websites were analysed for content (multidisciplinary care team, qualified dentist, treatment contraindications and side effects), as well as for quality (DISCERN instrument, HONcode) and readability scores (Flesch Reading Ease, FRE and Flesch-Kincaid Reading Grade, FKG). RESULTS: Totally, 155 websites were included: 53% from health professionals, 20% commercial, 17% academic and 10% from non-health professionals. Content was incomplete, especially for commercial ones. 71.61% websites failed to acknowledge treatment contraindications, approximately 40.00% did not mention side effects and the need for a multidisciplinary care team, while 22.58% did not address the need to consult a qualified dentist. Quality and reliability were poor. Mean DISCERN score was 39.93 (95% CI 37.90-41.96), with lower scores for commercial websites compared with others. Only nine websites displayed HONcode certification. Readability was quite difficult, with mean FRE score of 59.50 (95% CI 57.58-61.42) and mean FKG level of 6.92 (95% CI 6.64-7.21). CONCLUSION: Health care professionals should be aware that currently available online information do not fulfil the most important aspects of MAD therapy and may be difficult to understand by laypeople. This could contribute to cause delays in appropriate OSA care and unrealistic treatment expectations, increasing the risk of treatment discontinuation.

Bone Modeling after Orthodontic Extrusion: A Histomorphometric Pilot Study.

During osteogenesis and bone modeling, high vascularity and osteoblastic/osteoclastic cell activity have been detected. A decrease in this activity is a sign of complete bone formation and maturation. Alveolar bone maturation seems to occur within weeks and months; however, the precise timing of the alveolar bone modeling is still unknown. The aim of this clinical pilot study was to investigate the bone modeling of neo-apposed tissue during orthodontic extrusive movements, through a histomorphometric analysis of human biopsies. This study was conducted on third mandibular molars sockets, and all teeth were extracted after orthodontic extrusion between 2010 and 2014. After different stabilization timings, extractions were performed, and a specimen of neo-deposed bone was harvested from each socket for the histomorphometric analysis. Histological parameters were evaluated to identify bone quantity and quality. This study included 12 teeth extracted from 9 patients. All specimens were composed of bone tissue. Bone samples taken after 1 and 1.5 months of stabilization presented remarkable percentages of woven bone, while after 2 months, a relevant decrease was observed. Histomorphometric analysis suggested that after orthodontic extrusion, a period of stabilization of 2 months allows the neo-deposed bone to mature.

Dropout and adherence of obstructive sleep apnoea patients to mandibular advancement device therapy: A systematic review of randomised controlled trials with meta-analysis and meta-regression.

BACKGROUND: Mandibular advancement devices (MADs) are used as an alternative to continuous positive airways pressure to treat obstructive sleep apnoea (OSA) patients, but to date, specific data on the adherence to MAD therapy are lacking. OBJECTIVES: The aim of the present systematic review was to investigate the dropout rate and adherence of OSA patients to different custom-made (CM) and non-custom-made (NCM) MAD therapies. SEARCH METHODS: An electronic search was performed in MEDLINE, Cochrane Database of Systematic Reviews, Scopus, LILACS and Web of Science. SELECTION CRITERIA: Randomised controlled trials (RCTs) assessing the compliance to customised and not customised MADs in the treatment of adult OSA patients were included. DATA COLLECTION AND ANALYSIS: The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) and the risk of bias by the Cochrane Collaboration's tool for assessing risk of bias in RCT. The dropout rate of each study was computed and the adherence to MAD therapy in terms of hours per night and nights per week was extracted from each study. RESULTS: Thirty-two RCTs were included. The risk of bias resulted low in most of the studies. The GRADE scores indicated that the quality of evidence was from very low to moderate. The meta-analyses showed that the mean dropout rate did not significantly differ between CM and NCM MADs: The overall mean dropout rate was 0.171 [0.128-0.213] with a mean follow-up of 4.1 months. The hours per night adherence was significantly higher for CM MADs (6.418 [6.033-6.803]) compared to NCM MADs (5.107 [4.324-5.890]. The meta-regression showed that the dropout rate increases significantly during time (p < .05). CONCLUSIONS: There is a very low to moderate quality of evidence that the dropout rate of MAD therapy is similar among CM and NCM MADs, that the dropout rate increases significantly during time and that CM MADs have higher hours per night adherence compared with NCM MAD. REGISTRATION: The study protocol was registered on PROSPERO (n. CRD42020199866).

Obstructive sleep apneas naturally occur in mice during REM sleep and are highly prevalent in a mouse model of Down syndrome.

STUDY OBJECTIVES: The use of mouse models in sleep apnea study is limited by the belief that central (CSA) but not obstructive sleep apneas (OSA) occur in rodents. We aimed to develop a protocol to investigate the presence of OSAs in wild-type mice and, then, to apply it to a validated model of Down syndrome (Ts65Dn), a human pathology characterized by a high incidence of OSAs. METHODS: In a pilot study, nine C57BL/6J wild-type mice were implanted with electrodes for electroencephalography (EEG), neck electromyography (nEMG), and diaphragmatic activity (DIA), and then placed in a whole-body-plethysmographic (WBP) chamber for 8 h during the rest (light) phase to simultaneously record sleep and breathing activity. CSA and OSA were discriminated on the basis of WBP and DIA signals recorded simultaneously. The same protocol was then applied to 12 Ts65Dn mice and 14 euploid controls. RESULTS: OSAs represented about half of the apneic events recorded during rapid-eye-movement-sleep (REMS) in each experimental group, while the majority of CSAs were found during non-rapid eye movement sleep. Compared with euploid controls, Ts65Dn mice had a similar total occurrence rate of apneic events during sleep, but a significantly higher occurrence rate of OSAs during REMS, and a significantly lower occurrence rate of CSAs during NREMS. CONCLUSIONS: Mice physiologically exhibit both CSAs and OSAs. The latter appear almost exclusively during REMS, and are highly prevalent in Ts65Dn. Mice may, thus, represent a useful model to accelerate the understanding of the pathophysiology and genetics of sleep-disordered breathing and to help the development of new therapies.

Non-continuous positive airway pressure treatment options in obstructive sleep apnoea: A pathophysiological perspective.

The phenotyping of the pathophysiology of obstructive sleep apnoea (OSA) lies at the core of tailored treatments and it is one of the most debated topics in sleep medicine research. Recent sophisticated techniques have broadened the horizon for gaining insight into the variability of the endotypic traits in patients with OSA which account for the heterogeneity in the clinical presentation of the disease and consequently, in the outcome of treatment. However, the implementation of these concepts into clinical practice is still a major challenge for both researchers and clinicians in order to develop tailored therapies targeted to specific endotypic traits that contribute to OSA in each individual patient. This review summarizes available scientific evidence in order to point out the links between endotypic traits (pharyngeal airway collapsibility, upper airway neuromuscular compensation, loop gain and arousal threshold) and the most common non-continuous positive airway pressure (CPAP) treatment options for OSA (mandibular advancement device, upper airway surgery, medication therapy, positional therapy) and to clarify to what extent endotypic traits could help to better predict the success of these therapies. A narrative guide is provided; current design limitations and future avenues of research are discussed, with clinical and research perspectives.

Diagnostic accuracy of screening questionnaires for obstructive sleep apnea in children: A systematic review and meta-analysis.

This systematic review and meta-analysis evaluated the diagnostic accuracy of screening questionnaires for pediatric obstructive sleep apnea (OSA). Studies comparing any questionnaire with polysomnography for OSA detection in subjects aged ≤18 y were considered eligible for qualitative analysis. The quality assessment of diagnostic accuracy studies (QUADAS-2) tool was used for bias assessment. Only questionnaires adopted by at least four studies using the currently accepted diagnostic threshold of apnea-hypopnea index (AHI) ≥1 were included for further selective quantitative analyses. A bivariate meta-analysis was performed to calculate sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratio; summary receiver operator characteristic curves were constructed. 37 studies (20 questionnaires) were eligible for qualitative analysis; none were considered of low quality. Among these articles, 13 studies and two questionnaires (sleep-related breathing disorder scale of the pediatric sleep questionnaire (SRBD-PSQ) and OSA-18) satisfied the criteria for quantitative synthesis. SRBD-PSQ had higher sensitivity (0.76) than OSA-18 (0.56), while OSA-18 exhibited higher specificity (0.73) than SRBD-PSQ (0.43). SRBD-PSQ performed well and was the most sensitive screening questionnaire using the diagnostic threshold of AHI ≥1 for pediatric OSA. However, further well-designed studies are still required to assess the role of SRBD-PSQ in real-world clinical populations.

Effectiveness of different mandibular advancement device designs in obstructive sleep apnoea therapy: A systematic review of randomised controlled trials with meta-analysis.

Mandibular advancement devices (MADs) are used to treat patients with obstructive sleep apnoea (OSA). To date, there are no data that identify the most effective MAD design for apnoea-hypopnea index (AHI) reduction. The purpose of this systematic review is to investigate the effectiveness of different MAD designs in AHI reduction and oxygen saturation improvement in OSA patients. An electronic search was performed in MEDLINE, Cochrane Database, Scopus, Web of Knowledge and LILACS. Randomised controlled trials (RCTs) investigating the reduction of AHI on adult patients wearing MAD for OSA were included. The quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) and the risk of bias by the Cochrane Collaboration's tool for assessing risk of bias in randomised controlled trial. The success rate of each study was computed: [(mean baseline AHI - mean AHI after treatment)/mean baseline AHI]. Fifty RCTs were included. The risk of bias resulted with some concerns in most of the studies. The GRADE scores indicated that the quality of evidence was very low. The meta-analysis showed a success rate with mono-bloc and duo-bloc MADs respectively of 0.821 [0.722-0.887] and 0.547 [0.443-0.637]. The mono-bloc compared with duo-bloc better improved the minimum oxygen saturation (10.048 [7.733-12.363] and 3.357 [2.290-4.423], respectively). There is a very low quality body of evidence that mono-bloc MADs are more effective in reducing AHI and improving minimum oxygen saturation compared with duo-bloc MADs. The study protocol was registered on PROSPERO (n. CRD42019118084).

Short-term effects of the Sander bite-jumping appliance on the pharyngeal airways in subjects with skeletal Class II malocclusion: A retrospective case-control study.

BACKGROUND: Skeletal Class II subjects present often a retruded mandible that might increase the probability of breathing disorders. OBJECTIVE: To evaluate the effects of functional treatment by means of the Sander bite-jumping appliance (BJA) on the upper airways of growing subjects. METHODS: Thirty-four subjects (21 males, 13 females; mean age 11.1 ± 1.2 years) with skeletal Class II malocclusion due to mandibular retrusion were treated with the Sander BJA (BJA group). The control group consisted of thirty-four untreated subjects with skeletal Class II malocclusion (25 males, 9 females; 10.4 ± 1.2 years; CTR group). The effect of the Sander BJA appliance on the airway dimensions was evaluated by comparing lateral cephalograms recorded before (T0) and after (T1) the period of observation/treatment. Within- and between-group comparisons were statistically evaluated according to the distribution of the data (P < .05). RESULTS: The oropharyngeal region (ph_pph) increased in the BJA group (1.8 ± 3.2; P = .001) but the difference respect to the CTR group was not statistically significant (0.73 ± 4.0; P = .314; P = .077). The tongue height (th) increased in the BJA group (2.8 ± 3.7; P < .001), and this increase was statistically significant respect to the CTR group (0.6 ± 4.7; P = .461; P = .038). In the BJA, the Ans_Pns_P angle showed a statistically significant decrease (-3.8 ± 7.8; P = .007) compared to the CTR group (-0.1 ± 5.4; P = .705; P = .026). CONCLUSIONS: The airway dimensions increased for both control subjects and Class II patients treated with Sander BJA due to physiological growth. The Sander BJA induced a statistically significant change in the tongue and soft palate position, but the clinically relevant of these changes is questionable.

Upper airway collapsibility in patients with OSA treated with continuous positive airway pressure: a retrospective preliminary study.

STUDY OBJECTIVES: To investigate the prevalence of mildly collapsible upper airways (defined by therapeutic continuous positive airway pressure [CPAP] values ≤ 8 cm H2O) in moderate to severe obstructive sleep apnea patients treated with CPAP and to determine their clinical, functional, and nocturnal polysomnographic characteristics. METHODS: Eighty-seven patients with moderate to severe obstructive sleep apnea consecutively treated with CPAP were retrospectively investigated. Two nocturnal home sleep portable monitoring studies were performed at baseline and during treatment. Participants were categorized according to therapeutic CPAP values: ≤ 8 cm H2O (group 1), 8-12 cm H2O (group 2), ≥ 12 cm H2O (group 3). Anthropometric, awake respiratory function, symptoms, comorbidities, and nocturnal home sleep portable monitoring studies data were collected. RESULTS: Mild upper airway collapsibility (therapeutic CPAP values ≤ 8 cm H2O) was present in 25.3% of patients. They showed more favorable apnea-hypopnea index, oxygen desaturation index, mean nocturnal saturation, sleep time with oxygen saturation < 90%, desaturation nadir, and supine position. Oxygen desaturation index showed a weak association with anatomical collapsibility. Using the receiver operating characteristic curve, the area under the curve for the oxygen desaturation index vs CPAP pressure requirements ≤ 8 cm H2O was low and oxygen desaturation index ≤ 40.8/h showed a sensitivity of 63.3% and a specificity of 69.2% to detect patients with mild collapsibility. CONCLUSIONS: A quarter of moderate to severe patients under CPAP therapy had mild collapsibility and were likely to also be good candidates for alternative and better tolerated non-CPAP therapies. Baseline anthropometric, clinical, and respiratory function characteristics did not predict mild upper airway collapsibility determined by CPAP pressure requirements ≤ 8 cm H2O.

Mechanical Properties of Thermoplastic Polymers for Aligner Manufacturing: In Vitro Study.

The use of metal-free thermoplastic materials plays a key role in the orthodontic digital workflow due to the increasing demand for clear aligner treatments. Three thermoplastic polymers commonly used to fabricate clear aligners, namely Duran®, Biolon® and Zendura®, were investigated to evaluate the effect of thermoforming (T.), storage in artificial saliva (S.A.S.) and their combination on their mechanical properties. Elastic modulus and yield stress of the specimens were characterized. Each material was characterized for each condition through tensile tests (ISO527-1). The results showed that thermoforming does not lead to a significant decrease in yield stress, except for Zendura® that showed about a 30% decrease. An increase of the elastic modulus of Duran® and Zendura®, instead, was observed after thermoforming. The same increase was noticed for the yield stress of Duran®. For S.A.S. specimens, the elastic modulus generally decreases compared to supplier condition (A.S.) and simply thermoformed material. A decrease of yield stress, instead, is significant for Zendura®. The results demonstrated that the impact of the operating conditions on the mechanical properties can vary according to the specific polymer. To design reliable and effective orthodontic treatments, the materials should be selected after their mechanical properties are characterized in the simulated intraoral environment.

Effect of Chitosan as a Cross-Linker on Matrix Metalloproteinase Activity and Bond Stability with Different Adhesive Systems.

The aim of the present study was to evaluate the effect of 0.1% chitosan (Ch) solution as an additional primer on the mechanical durability and enzymatic activity on dentine using an etch-and-rinse (E&R) adhesive and a universal self-etch (SE) adhesive. Microtensile bond strength and interfacial nanoleakage expression of the bonded interfaces for all adhesives (with or without pretreatment with 0.1% Ch solution for 1 min and air-dried for 5 seconds) were analyzed immediately and after 10,000 thermocycles. Zymograms of protein extracts from human dentine powder incubated with Optibond FL and Scotchbond Universal on untreated or Ch-treated dentine were obtained to examine dentine matrix metalloproteinase (MMP) activities. The use of 0.1% Ch solution as an additional primer in conjunction with the E&R or SE adhesive did not appear to have influenced the immediate bond strength (T0) or bond strength after thermocycling (T1). Zymography showed a reduction in MMP activities only for mineralized and demineralized dentine powder after the application of Ch. Application of 0.1% Ch solution does not increase the longevity of resin-dentine bonds. Nonetheless, the procedure appears to be proficient in reducing dentine MMP activities within groups without adhesive treatments. Further studies are required to comprehend the cross-linking of Ch with dentine collagen.