Lead Author Affiliation

Nikola Vranjes, DDS

Lead Author Status

Other

Expected Graduation Date

2020

Presentation Category

Research

Introduction/Context/Diagnosis

Oral appliance therapy (OAT) has been shown to successfully treat patients with obstructive sleep apnea/hypopnea syndrome (OSAHS). However, OAT is often associated with the occurrence of side effects such as unwanted tooth movement. Positive airway pressure therapy is more commonly used to treat OSAHS, because of the reluctance to prescribe OAT as a result of these side effects. Even so, Pliska does report on tooth movement due to tongue thrusting as a result of the use of positive airway pressure. Although OAT is an effective treatment for OSAHS along with its greater compliance, long-term use of some oral appliances has been shown to result in several side effects, including tooth movement. Past studies have shown this to result in significant effects, such as craniofacial changes, anteroposterior positioning of the molars, inclination of the upper and lower incisors, and irregularity of the lower incisors. According to the American Academy of Dental Sleep Medicine’s published article on management of side effects, tooth movement (specifically occlusal changes represented by incisor changes, position of canines, decreased overjet/overbite, and altered occlusal contacts/bite changes) is one of the five significant concerns during the treatment of obstructive sleep apnea using an oral appliance. It was reported that there is a significant difference in anterior crowding using a flexible oral appliance without incisor coverage versus a rigid OA. The rigid OA demonstrated less tooth movement. Recently, new devices with proprietary computer-aided design/computer-aided manufacturing (CAD/CAM) technology have been introduced and made available to clinicians. This study aims to investigate the changes in tooth movement with a hard-acrylic rigid oral appliance, the ProSomnus® Sleep Appliance, over a 2-year period. This research project was based on an approved Internal Review Board (IRB) protocol.

Methods/Treatment Plan

Patients were accepted into the study who were willing to return for follow-up impressions to be taken at the respective time points of 1 and 2 years. Patients were recruited from a pool of randomly selected patients (n=53) from an earlier study with an acceptance criterion of body mass index less than 35 kg/m2 and AHI greater than 10 events per hour. Eighteen of the 53 patients (14 male/4 female) with sleep apnea were recruited for this study. Average patient age was 54 years, with an overall pretreatment AHI of 25.4 events per hour and posttreatment AHI of 6.7 events per hour (Table 1). Patients’ pretreatment impressions were taken and the bite position captured using the George Gauge, and patients were fitted with a ProSomnus® Sleep Appliance (Figure 1) at The Snore Centre in Calgary. Patients were not fitted with a morning aligner. The patient’s bite was determined by the MATRx (Zephyr Sleep Technologies, Calgary, AB, Canada) target position in which the bite position was at a percentage of maximum protrusion ranging from 40% to 100%. Polyvinylsiloxane impressions were taken at baseline, after approximately 1 year (mean = 1.2 years) and after 2 years (mean = 2.3 years) of use with the oral appliance. Patients were surveyed on compliance and quality of life using the Sleep Apnea Quality of Life Index (SAQLI). The compliance survey asked patients to subjectively report on their compliance; patients were asked if they wore their appliance more than 4 hours per night, more than 5 days per week. The SAQLI survey was given to patients at the 1- and 2-year time points. The initial time point was unavailable as recruited patients had already been wearing their appliances upon study initiation. Models were marked, per the IRB, to scrub the patient data and to obscure the time points of each patient, from the measurement technician, to reduce measurement bias. Statistical analysis was completed by a separate party not involved in the measurement procedure. The mixed-effects model for analysis was chosen to provide the best estimates of the mean and confidence intervals. This model deals more adequately with the variable number of measurement replicates at each time point for each subject. Patient models (Figure 2) were scanned on a TRIOS lab scanner (3Shape, Copenhagen, Denmark) and scored using 3Shape OrthoAnalyzer software (3Shape, Copenhagen, Denmark). The upper and lower anterior teeth crowding was calculated using the Little Irregularity Index method (Figure 3). The models were placed in maximum intercuspation (MIP) and scanned, and overjet and overbite were measured using 3Shape OrthoAnalyzer software (Figure 4). Scanning and measurements were completed by the University of Pacific School of Dentistry.

Results/Outcome

At the beginning of the study, the anterior upper and lower arches were measured in each patient. The same measurements were done after an average of 1.2 years. Variation from time zero to year 1 for individual pairs of teeth, for example, between 27-26 on the lower arch and 8-9 on the upper arch, had an overall average shift of -.022 mm for the upper arch and -.014 mm for the lower arch. The average difference for the total Little Irregularity Index for the same 18 patients at an average of 2.3 years for the upper arch was -0.007 mm. The average difference for the lower arch was 0.003 mm total. Within this study sample size, these differences were not shown to be statistically significant. The average change in the patients’ overbite after 2.3 years was 0.0045 mm and for overjet -.015 mm.

Significance/Conclusions

Sleep physicians and general dentists often cite side effects as a leading reason to avoid OAT. Of the many possible side effects related to OAT, tooth movement is one that is discussed, and is relatively easy to measure, especially with the advent of digital scanners. When it comes to choosing an oral appliance, clinicians now have a wide variety of appliance designs and materials. Appliances that have areas of stronger pressure, such as ball clasps or open areas, are much more likely to result in tooth movement, rather than an appliance that covers every tooth. Similarly, a hard acrylic rigid appliance is likely to provide more tooth stability than a softer appliance. An appliance designed with a proprietary CAD/CAM process, made of hard acrylic with an even spacer around all areas in contact with the teeth, is therefore thought to provide enough stability to prevent tooth movement.

The study results show that when patients are compliant in wearing the appliance chosen in this study nightly (ProSomnus® Sleep Appliance) the data report minimal tooth movements, if any. Another significant finding discovered is that when models are hand-articulated into MIP, overjet and overbite did not change. The changes noted in this study appear to be less than in previous oral appliance studies. Additionally, a key component to any treatment is acceptance of the oral appliance and the willingness to wear the device long term. Treatment compliance is required to obtain useful efficacy. The survey results demonstrated that patients wore the device at a high rate and would recommend the device to friends and family. This clinical study demonstrates that the proprietary CAD/CAM oral appliance minimizes tooth movement, and patients found the appliance comfortable and favorable. From a clinician’s point of view, these study results can help alleviate concern from three audiences: the patient, a patient’s referring dentist, and a sleep physician. These key findings provide additional evidence and information for dental/orthodontic practitioners when prescribing OAT for OSAHS.

The challenge of understanding the significance of tooth movement by an appliance is understanding the natural amount of tooth movement that may occur without an appliance. Future studies should include a control to establish what is typical tooth movement for a comparative patient population. This can be tricky as a treated versus untreated population may have different degrees of tooth movement. Because the patient may have many factorsthat could affect tooth mobility and subsequent tooth movement due to natural and iatrogenic sources, the authors chose a relative comparison of the patient’s own data to specifically investigate the effect on the device to unwanted tooth movement. The study was limited by the ability to obtain surveys from all participants; many did not respond to further requests to create a complete dataset for the surveys. Understanding the change in the habitual bite was difficult in this case and the authors focused on the MIP of the patients’ models with the data available. A more in-depth look at the patients’ natural s bite via an intraoral scan, and cephalometric analysis and inspection of the temporal mandibular joint may provide a better understanding of bite changes. More studies are suggested to consider the many variables that contribute to occlusal changes and habitual bite changes and the tradeoffs to treating patients experiencing the effects of obstructive sleep apnea.

Comments/Acknowledgements

An IRB protocol for the clinical trial in Canada was approved by the Health Research Ethics Board of Alberta, Canada.

The authors would like to thank and acknowledge support from University of Pacific, Arthur A. Dugoni School of Dentistry, Department of Preventive and Restorative Dentistry (San Francisco, CA). The authors also thank ProSomnus Sleep Technologies (Pleasanton, CA) for financial support, for technical support (3Shape OrthoAnalyzer Software) by Joshua Seefeldt at Argen (San Diego, CA), for statistical support from Colleen Kelly at Kelly Statistical Consulting (San Diego, CA), and the staff at Snore Centre Quarry Park (Calgary, AB, Canada).

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Assessment of Potential Tooth Movement and Bite Changes With a Hard-Acrylic Sleep Appliance: A 2-Year Clinical Study

Oral appliance therapy (OAT) has been shown to successfully treat patients with obstructive sleep apnea/hypopnea syndrome (OSAHS). However, OAT is often associated with the occurrence of side effects such as unwanted tooth movement. Positive airway pressure therapy is more commonly used to treat OSAHS, because of the reluctance to prescribe OAT as a result of these side effects. Even so, Pliska does report on tooth movement due to tongue thrusting as a result of the use of positive airway pressure. Although OAT is an effective treatment for OSAHS along with its greater compliance, long-term use of some oral appliances has been shown to result in several side effects, including tooth movement. Past studies have shown this to result in significant effects, such as craniofacial changes, anteroposterior positioning of the molars, inclination of the upper and lower incisors, and irregularity of the lower incisors. According to the American Academy of Dental Sleep Medicine’s published article on management of side effects, tooth movement (specifically occlusal changes represented by incisor changes, position of canines, decreased overjet/overbite, and altered occlusal contacts/bite changes) is one of the five significant concerns during the treatment of obstructive sleep apnea using an oral appliance. It was reported that there is a significant difference in anterior crowding using a flexible oral appliance without incisor coverage versus a rigid OA. The rigid OA demonstrated less tooth movement. Recently, new devices with proprietary computer-aided design/computer-aided manufacturing (CAD/CAM) technology have been introduced and made available to clinicians. This study aims to investigate the changes in tooth movement with a hard-acrylic rigid oral appliance, the ProSomnus® Sleep Appliance, over a 2-year period. This research project was based on an approved Internal Review Board (IRB) protocol.