Benjamin T. Pliska

Dosimetry of a cone-beam computed tomography machine compared with a digital x-ray machine in orthodontic imaging

INTRODUCTION Cone-beam computed tomography (CBCT) has become a routine imaging modality for many orthodontic clinics. However, questions remain about the amount of radiation patients are exposed to during the scans. This study determined the amounts of radiation potentially absorbed by a patient during orthodontic imaging with a CBCT machine with various scan settings compared with a conventional 2-dimensional digital x-ray machine. METHODS The radiation exposures delivered by a next generation i-CAT CBCT machine (Imaging Sciences International, Hatfield, Pa) at various scan settings and orthopantomograph OP100/OC100 digital x-ray machine (Instrumentarium Dental, Tuusula, Finland) during panoramic and cephalometric radiography were recorded using thermoluminescent dosimeters placed inside a head and neck phantom. The manufacturer-recommended settings for an average adult male were used for both types of machines. Effective doses were calculated using the tissue-weighting factors recommended by the 2007 International Commission on Radiological Protection. RESULTS The effective doses at various voxel sizes and field of view settings ranged from 64.7 to 69.2 μSv for standard resolution CBCT scans (scan time 8.9 s) and 127.3 to 131.3 μSv for high resolution full field of view scans (scan time 17.8 s), and measured 134.2 μSv for a high-resolution landscape scan with a voxel size as would be used for SureSmile (OraMetrix, Richardson, Tex) therapy (scan time 26.9 s). The effective doses for digital panoramic and lateral cephalometric radiographs measured 21.5 and 4.5 μSv, respectively. CONCLUSIONS CBCT, although providing additional diagnostic and therapeutic benefits, also exposes patients to higher levels of radiation than conventional digital radiography.

Patient preferences and experiences of CPAP and oral appliances for the treatment of obstructive sleep apnea: a qualitative analysis

ObjectivesThe aim of this study is to better understand patients’ perspectives and preferences about treatment with continuous positive airway pressure (CPAP) and oral appliance (OA) devices for obstructive sleep apnea.MethodsThe current study used qualitative analysis of four focus group sessions with current CPAP and OA users. Twenty-two participants with OSA who currently use either CPAP or OA participated in the sessions at the University of British Columbia.ResultsFive topics from the focus group sessions were descriptively analyzed using NVivo software: goals and expectations of treatment, benefits of treatment for bed partners, side effects and inconveniences of CPAP, side effects and inconveniences of OA, and factors impacting treatment choice. In order of most to least frequently mentioned, patients expressed six expectations of treatment: improved health, apnea elimination, improved sleep, reduced fatigue, reduced snoring, and bed-partner benefits. The most to least mentioned factors impacting treatment choice were device effectiveness, transportability, embarrassment, and cost.ConclusionsThis qualitative study showed that many factors impact patients’ experience with their treatment device and that their treatment needs are not only physical but also relate to their lifestyle. This preliminary study provides treatment characteristics and attributes necessary to develop a quantitative questionnaire study, to assist in the selection of therapy, weighing the relative importance of patient and OSA treatment characteristics on treatment preference and adherence. Matching therapy to patient preferences may help identify the most appropriate treatment, and this may achieve greater likelihood of adherence.

Obstructive sleep apnea and mandibular advancement splints: occlusal effects and progression of changes associated with a decade of treatment.

STUDY OBJECTIVES To evaluate the magnitude and progression of dental changes associated with long-term mandibular advancement splint (MAS) treatment of obstructive sleep apnea (OSA). METHODS Retrospective study of adults treated for primary snoring or mild to severe OSA with MAS for a minimum of 8 years. The series of dental casts of patients were analyzed with a digital caliper for changes in overbite, overjet, dental arch crowding and width, and inter-arch relationships. The progression of these changes over time was determined and initial patient and dental characteristics were evaluated as predictors of the observed dental side effects of treatment. RESULTS A total of 77 patients (average age at start of treatment: 47.5 ± 10.2 years, 62 males) were included in this study. The average treatment length was 11.1 ± 2.8 years. Over the total treatment interval evaluated there was a significant (p < 0.001) reduction in the overbite (2.3 ± 1.6 mm), overjet (1.9 ± 1.9 mm), and mandibular crowding (1.3 ± 1.8 mm). A corresponding significant (p < 0.001) increase of mandibular intercanine (0.7 ± 1.5 mm) and intermolar (1.1 ± 1.4 mm) width as well as incidence of anterior crossbite and posterior open bite was observed. Overbite and mandibular intermolar distance were observed to decrease less with time, while overjet, mandibular intercanine distance, and lower arch crowding all decreased continuously at a constant rate. CONCLUSIONS After an average observation period of over 11 years, clinically significant changes in occlusion were observed and were progressive in nature. Rather than reaching a discernible end-point, the dental side effects of MAS therapy continue with ongoing MAS use. COMMENTARY A commentary on this article appears in this issue on page 1293.

Effectiveness and Outcome of Oral Appliance Therapy

Oral appliances (OAs) are a primary treatment option for snoring and mild to moderate obstructive sleep apnea (OSA) and are implemented as a noninvasive alternative for patients with severe OSA who are unwilling or unable to tolerate continuous positive airway pressure for the management of their disease. Studies have demonstrated the ability of OAs to eliminate or significantly reduce the symptoms of OSA and produce a measurable influence on the long-term health effects of the disease. Most studies have evaluated one type of OAs, the mandibular advancement splints. This article describes the effectiveness and outcomes of mandibular advancement splints.

Prediction of oral appliance treatment outcomes in obstructive sleep apnea: A systematic review

While oral appliances (OA) have demonstrated good efficacy in patients ranging from mild to severe levels of obstructive sleep apnea (OSA), this form of treatment is not completely effective in all patients. As a successful treatment response is not dependent solely on apnea hypopnea index severity, the prediction of OA treatment efficacy is of key importance for efficient disease management. This systematic review aims to investigate the accuracy of a variety of clinical and experimental tests for predicting OA treatment outcomes in OSA. A systematic literature review was conducted and the quality of the selected studies was assessed using the quality assessment of diagnostic accuracy studies (QUADAS-2) tool. Some 17 studies involving various prediction methods were included in this review. The predictive accuracy varied depending on the definitions of treatment success used as well as the type of index test. The studies with the best predictive accuracy and lowest risk of bias and concerns of applicability used a multisensor catheter. While a remotely controlled mandibular positioner study showed high accuracy, there was a high risk of bias. The available information on the validity of predictive index tests is very useful in clinical practice and allows for greater disease management efficiency.

Treatment of white spot lesions with ACP paste and microabrasion.

OBJECTIVE To examine the effects of application of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) paste and microabrasion treatment on the regression of white spot lesions (WSLs). MATERIALS AND METHODS Artificially-induced WSLs in bovine enamel were randomly assigned to one of four treatment groups: CPP-ACP paste only, microabrasion only, microabrasion and CPP-ACP, and a control. Samples were treated with each regimen twice daily for 2 weeks and stored in remineralizing solution between the treatments. Quantitative light-induced fluorescence was used to measure changes in fluorescence, which indicate changes in mineral content of WSLs immediately before (T1) and 2 weeks after treatment (T2). A two-within-subject factor analysis of variance was used to analyze the significance of any changes in mineral content of the lesions from T1 to T2. RESULTS There was a statistically significant (P < .05) gain in fluorescence associated with the microabrasion only, as well as the microabrasion and CPP-ACP treatments. The changes in fluorescence for the CPP-ACP treatment alone were not statistically significant (P  =  .40). CONCLUSIONS CPP-ACP paste alone does not significantly improve the fluorescence value (ie, the mineral content) of WSLs. Within the limitations of this in vitro study, microabrasion treatment with or without CPP-ACP improved the fluorescence and thus reduced WSLs.

Endoscopy evaluation to predict oral appliance outcomes in obstructive sleep apnoea

The objective of this study was to determine the utility of nasoendoscopy of the upper airway as a predictor of the efficacy of oral appliance treatment in obstructive sleep apnoea (OSA). A total of 61 consecutive patients with moderate-to-severe polysomnographically diagnosed OSA were recruited for this study. Using nasoendoscopy, we prospectively assessed the velopharynx and oro/hypopharynx in each patient while awake and in the supine position. We measured cross-sectional area (CSA), and anteroposterior and lateral diameters of the airway before and after mandibular advancement, and expressed the changes in dimensions as expansion ratios (after/before). We then compared the measurements of responders and nonresponders with oral appliance treatment. The expansion ratio (median (interquartile range)) for the CSA was greater in responders compared with nonresponders in the velopharynx (2.9 (2.3–5.0) versus 1.7 (1.5–1.9), p<0.001) and in the oro/hypopharynx (3.4 (2.5–5.6) versus 2.4 (1.8–3.7), p<0.05). Baseline apnoea–hypopnoea index and the CSA expansion ratio of the velopharynx were independent predictors of oral appliance treatment outcome based on a multivariate logistic regression analysis. The estimated area under the receiver operator characteristic curve was 0.87 and the cut-off value of the expansion ratio was 2.00. These results indicate that nasoendoscopy may have significant clinical utility in predicting the success of oral appliance treatment. A pronounced increase of the velopharynx with mandibular protrusion is a good predictor of oral appliance success http://ow.ly/V9lBU

A comparison of resistance to sliding of self-ligating brackets under an increasing applied moment.

OBJECTIVE To test the null hypotheses that at clinically relevant amounts of applied moment, there are no differences in the amount of resistance to sliding (RS) between self-ligating (SL) and conventionally ligated (CL) brackets on both stainless steel (SS) and nickel-titanium (NT) archwire. MATERIALS AND METHODS Three different SL brackets and one CL bracket, all 0.022″ slot, were tested on a custom-built device to simulate canine retraction mechanics in the second-order dimension. The setup allowed for simultaneous and continuous measurement of RS and applied moment at the bracket-archwire interface. The brackets tested were Damon3, In-Ovation R, Smartclip, and Victory, all of which were tested with 0.019″ × 0.025″ SS and NT archwires. The RS at calculated moments of 2000 g-mm and 4000 g-mm was determined and compared between the various brackets and both archwire types. Descriptive measures, analysis of variance, and Tukey-Kramer post-test comparisons were used to calculate results. RESULTS All brackets displayed a greater amount of RS with NT than with SS archwires. At the higher moment levels (4000 g-mm), no significant reduction in RS was found between CL and SL brackets on both SS and NT archwires. At lower levels of applied moment (2000 g-mm), reductions in RS of 18% (42.7 g) and 18% (38.5 g) were found between the CL bracket and the best performing SL bracket on NT and SS, respectively. CONCLUSION At low values of applied moment, some statistical differences were found; however, in general, the differences in RS amongst the various SL and CL brackets tested may not be clinically relevant.

Effect of applied moment on resistance to sliding among esthetic self-ligating brackets

OBJECTIVE To determine the effect of mode of ligation and bracket material on resistance to sliding (RS) by comparing various esthetic brackets of conventionally ligated and self-ligating (SL) designs under an increasing applied moment in the second-order dimension. MATERIALS AND METHODS Eight different commercially available esthetic brackets of SL and conventional elastomeric-ligated (CL) designs were mounted on a testing apparatus to simulate canine retraction using sliding mechanics and the application of a moment on 0.019″×0.025″ stainless steel archwire. The samples examined were the CL brackets Clarity™, Inspire Ice™, SpiritMB™, and Mystique™, and the SL brackets ClaritySL™, In-OvationC™, In-OvationR™, and Smartclip™. The RS at calculated moments of 2000 g-mm and 4000 g-mm was determined and compared between the various brackets. Descriptive measures and one-way analysis of variance were used to calculate means and statistical differences among the bracket types. RESULTS The CL monocrystalline bracket displayed significantly greater (P < .05) RS than all other brackets tested. Among the other brackets, the range of RS values was 145.8-191.7 g and 291.9-389.2 g at moments of 2000 g-mm and 4000 g-mm, respectfully, though these differences were not significant (P < .05). All brackets tested displayed greater levels of RS (P < .05) at 4000 g-mm than at 2000 g-mm. CONCLUSION With the exception of the CL monocrystalline bracket, all brackets displayed comparable amounts of RS regardless of mode of ligation or bracket slot material.

Reliability of upper pharyngeal airway assessment using dental CBCT: a systematic review

Background Upper airway analysis is an often-cited use of cone beam computed tomography (CBCT) imaging in orthodontics. However, the reliability of this process in a clinical setting is largely unknown. Objective Our objective was to systematically review the literature to evaluate the reliability of upper pharyngeal airway assessment using dental CBCT. Search methods MEDLINE, EMBASE, Web of Science, and Google Scholar were searched through June 2015. Selection criteria Human studies that measured reliability of upper airway assessment in patients using CBCT as part of the study protocol were considered. Data collection and analysis The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) was followed. Data were collected on overall study characteristics and measurements, CBCT unit and machine settings used, and examination characteristics of the included studies. Methodological quality of the included studies was evaluated. Results Forty-two studies were evaluated, representing the CBCT scans of 956 patients. Studies included a wide variety of patients and CBCT machines with various scan settings. Only five studies were deemed high quality. The available evidence indicates that under specific restricted conditions there is moderate to excellent intra- and inter-examiner reliability. Airway volume demonstrated greater intra- and inter-examiner reliability than did minimum cross-sectional area. However, significant methodological limitations of the current literature, most importantly a lack of manual orientation of the images and selection of threshold sensitivity in study protocols, suggest that reliability has not been adequately established. Conclusions The current literature reports moderate to excellent reliability, with airway volume having higher reliability than minimum cross-sectional area. However, only limited aspects of the process of airway analysis have been evaluated, indicating that further research is required to adequately establish the reliability of upper pharyngeal airway assessment of patients using dental CBCT. Registration None.