Reyes Enciso

Oropharyngeal airway changes after rapid palatal expansion evaluated with cone-beam computed tomography

INTRODUCTION The aims of this retrospective study were to use cone-beam computed tomography (CBCT) to assess changes in the volume of the oropharynx in growing patients with maxillary constriction treated by rapid palatal expansion (RPE) and to compare them with changes in age- and sex-matched orthodontic patients. METHODS The experimental group consisted of 24 patients (mean age, 12.8+/-1.88 years) with maxillary constriction who were treated with hyrax palatal expanders; the control group comprised 24 age- and sex-matched patients (mean age, 12.8+/-1.85 years) who were just starting regular orthodontic treatment. Beginning and progress CBCT scans, taken in the supine position, were analyzed with software to measure volume, length, and minimal cross-sectional area of the oropharyngeal airway. The 2 groups were compared with paired t tests. RESULTS Only retropalatal airway volume was found to be significantly different between groups before treatment (P = 0.011), and this difference remained after treatment (P = 0.024). No other statistically significant differences were found relative to changes in volume, length, or minimum cross-sectional area of the oropharyngeal airway between the groups, but the molar-to-molar width after RPE increased significantly compared with the controls (P <0.001). CONCLUSIONS Narrow oropharyngeal airways in growing patients with maxillary constriction was demonstrated. But there was no evidence to support the hypothesis that RPE could enlarge oropharyngeal airway volume.

Cone-beam computerized tomography evaluation of the maxillary dentoskeletal complex after rapid palatal expansion

INTRODUCTION Rapid palatal expansion (RPE) is routinely used to correct transverse deficiencies in the maxilla, but its effects on the dentoalveolus are uncertain. The purpose of this study was to compare measurements made on cone-beam computerized tomography scans between patients with RPE treatment and controls to determine transverse dimension increases and the amounts of alveolar and dental tipping. METHODS Twenty-five patients with posterior crossbite who required RPE treatment and 25 sex- and age-matched controls (no crossbite) were orthodontically treated and received cone-beam computerized tomography scans at the beginning and middle of treatment. Transverse widths and several angulations were measured, and matched paired t tests used. RESULTS RPE treatment produced a significant increase in all measured transverse dimensions. Analysis of posttreatment angulation changes in the RPE group showed that the alveolus substantially tipped buccally by nearly 5.6° (measured from a horizontal reference, the base of the hard palate). The angulations of the dentition, however, remained constant before and after treatment (<1° of change) in both groups. CONCLUSIONS These data showed no statistically significant amount of relative dental tipping after RPE treatment but significant alveolar tipping compared with the controls.

Treatment outcomes of mandibular advancement devices in positional and nonpositional OSA patients

OBJECTIVE The aim of the study was to investigate treatment outcome of mandibular advancement devices (MADs) for positional and nonpositional obstructive sleep apnea (OSA). STUDY DESIGN Forty-two positional (supine apnea-hypopnea index [AHI] > or = 2 times lateral AHI) and 30 nonpositional (supine AHI < 2 times lateral AHI) OSA patients performed 2-nights of sleep study before and after insertion of MADs. RESULTS The decreases in apnea severity based on a reduction in the overall and supine AHI values after MADs therapy were significantly greater for the positional OSA than nonpositional OSA group. A multiple linear regression analysis showed that decrease in overall AHI was significantly associated with being in the positional group (standardized coefficient = 0.505). Age, body mass index, gender, and time in supine position during sleep did not show significant associations with decrease in overall AHI after MAD therapy. CONCLUSION Our data suggest that MADs are more effective in positional OSA than nonpositional OSA patients.

Model sensitivity and use of the comparative finite element method in mammalian jaw mechanics: mandible performance in the gray wolf.

Finite Element Analysis (FEA) is a powerful tool gaining use in studies of biological form and function. This method is particularly conducive to studies of extinct and fossilized organisms, as models can be assigned properties that approximate living tissues. In disciplines where model validation is difficult or impossible, the choice of model parameters and their effects on the results become increasingly important, especially in comparing outputs to infer function. To evaluate the extent to which performance measures are affected by initial model input, we tested the sensitivity of bite force, strain energy, and stress to changes in seven parameters that are required in testing craniodental function with FEA. Simulations were performed on FE models of a Gray Wolf (Canis lupus) mandible. Results showed that unilateral bite force outputs are least affected by the relative ratios of the balancing and working muscles, but only ratios above 0.5 provided balancing-working side joint reaction force relationships that are consistent with experimental data. The constraints modeled at the bite point had the greatest effect on bite force output, but the most appropriate constraint may depend on the study question. Strain energy is least affected by variation in bite point constraint, but larger variations in strain energy values are observed in models with different number of tetrahedral elements, masticatory muscle ratios and muscle subgroups present, and number of material properties. These findings indicate that performance measures are differentially affected by variation in initial model parameters. In the absence of validated input values, FE models can nevertheless provide robust comparisons if these parameters are standardized within a given study to minimize variation that arise during the model-building process. Sensitivity tests incorporated into the study design not only aid in the interpretation of simulation results, but can also provide additional insights on form and function.

A new method to measure mesiodistal angulation and faciolingual inclination of each whole tooth with volumetric cone-beam computed tomography images

INTRODUCTION The purpose of this study was to develop a methodology to measure the mesiodistal angulation and the faciolingual inclination of each whole tooth (including the root) by using 3-dimensional volumetric images generated from cone-beam computed tomography scans. METHODS A plastic typodont with 28 teeth in ideal occlusion was fixed in position in a dry human skull. Stainless steel balls were fixed to the occlusal centers of the crowns and to the apices or bifurcation or trifurcation centers of the roots. Cone-beam computed tomography images were taken and rendered in Dolphin 3D (Dolphin, Chatsworth, Calif). The University of Southern California root vector analysis program was developed and customized to digitize the crown and root centers that define the long axis of each whole tooth. Special algorithms were used to automatically calculate the mesiodistal angulation and the faciolingual inclination of each whole tooth. Angulation measurements repeated 5 times by using this new method were compared with the true values from the coordinate measuring machine measurements. Next, the root points of 8 selected typodont teeth were modified to generate known angulation and inclination values, and 5-time repeated measurements of these teeth were compared with the known values. RESULTS Intraclass correlation coefficients for the repeated mesiodistal angulation and faciolingual inclination measurements were close to 1. Comparisons between our 5-time repeated angulation measurements and the coordinate measuring machines true angulation values showed 5 teeth with statistically significant differences. However, only the maxillary right lateral incisor showed a mean difference that might exceed 2.5° for clinical significance. Comparisons between the 5-repeated measurements of 8 teeth with known mesiodistal angulation and faciolingual inclination values showed no statistically significant differences between the measured and the known values, and no measurement had a 95% confidence interval beyond 1°. CONCLUSIONS We have developed the novel University of Southern California root vector analysis program to accurately measure each whole tooth mesiodistal angulation and faciolingual inclination, in a clinically significant level, directly from the cone-beam computed tomography volumetric images.

Soft palate length and upper airway relationship in OSA and non-OSA subjects

BACKGROUND The narrowest area of the airway between the posterior nasal opening and the epiglottis is usually located in the retro palatal area. Many consider this the most likely site of airway obstruction during an obstructive sleep apnea (OSA) event. The aim of this study was to investigate the differences in soft palate and airway length between OSA and non-OSA patients. METHODS In this study, we analyzed the ratio of the soft palate and the upper airway length in 45 consecutive patients. Twenty-five had an Apnea-Hypoapnea Index of more than five events per hour and were classified in the OSA group (male, 19; female, 6). These patients were compared with 20 normal controls (male, 12; female, 8). Controls who complained of snoring did have sleep studies (n=5). The other fifteen controls were clinically asymptomatic and did not have sleep studies. Medical computed tomography scans were taken to determine the length of the upper airway and the soft palate length measured in the midsagittal image. RESULTS Soft palate length was significantly larger in OSA patients compared to controls (p=0.009), and in men compared to women (p=0.002). However, there were no differences in airway length. The soft palate length, as a percent of oropharyngeal airway length, was significantly larger in OSA patients compared to controls (p= <0.0001) and in men compared to women (p=0.02). Soft palate length increases significantly with age by 0.3 mm per year in males (after adjustment for body mass index (BMI) and OSA). Soft palate length as a percent of airway length is larger in OSA patients and increases significantly with BMI in males only after adjusting for age. CONCLUSION In this study, OSA patients had a longer soft palate in proportion to their oropharyngeal airway compared to controls as well as men compared to women. This proportion could be used for identifying patients at risk for OSA in combination with age.

Evaluation of Root and Canal Morphology of Maxillary Permanent First Molars in a North American Population by Cone-beam Computed Tomography

INTRODUCTION The purpose of this study was to evaluate the number of roots and canal morphology of maxillary permanent first molars in a North American population. METHODS Three hundred seventeen cases with bilateral maxillary first molars were included. All images from cone-beam computed tomography were carefully reviewed by 2 endodontists. Frequency of number of roots, presence of an additional mesiobuccal canal (MB2), and Vertucci canal type for each root were tabulated. Age, gender, and ethnicity differences were calculated with the χ(2) test. The intra-rater reliability was assessed by using the Cohen kappa statistic. RESULTS The fused root rate was 0.9%. The occurrence of 3-rooted maxillary first molars differed between left and right sides (P = .03). MB2 occurrence only showed statistically significant differences among age groups (P = .005). In the mesiobuccal roots, the most common Vertucci classifications of canal types were type IV (2-2, 41.9%), type I (1, 28.3%), and type II (2-1, 26.3%). There was a statistically significant difference in Vertucci classification of canal type among 5 ethnic groups (African American, Asian, Hispanic, Other, and Non-Hispanic white, P < .001). CONCLUSIONS Cone-beam computed tomography facilitates the identification of root and canal configuration. The information gained about the tooth anatomy and canal morphology before treatment could potentially facilitate root canal therapy.

Is p16-positive oropharyngeal squamous cell carcinoma associated with favorable prognosis? A systematic review and meta-analysis.

The purpose of this systematic review and meta-analysis was to compare the prognosis of patients with p16 expressing oropharyngeal squamous cell cancers to patients with p16 non-expressing cancers. Clinical outcomes that were evaluated included overall survival, local recurrence, disease-free survival, disease-specific survival, and event-free survival. The following electronic databases were searched: Cochrane Library, MEDLINE (via Pubmed), and Web of Science. Publications were restricted to English language. Studies were limited to controlled clinical trials on the survival rates of patients with oropharyngeal tumors that were p16 expressing, compared to patients with p16 non-expressing tumors, and at least one clinical endpoint reported by trial authors (hazard ratios). Specific ascertainment criteria were applied for inclusion and exclusion of eligible studies. Data was independently extracted in duplicate. This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-analysis PRISMA checklist. Risk of bias was assessed for all included studies, and disagreements between review authors were discussed until an agreement was reached. Eighteen studies were included for final review and meta-analysis. The subgroup meta-analyses, which included survival and recurrence data, showed significantly favorable outcomes for patients with p16 expressing tumors. There is strong evidence to support that patients with p16 expressing oropharyngeal squamous cell cancers have favorable clinical outcomes and prognosis.

Comparing the Berlin and the ARES questionnaire to identify patients with obstructive sleep apnea in a dental setting

PurposeThe aim of this study was to compare the sensitivity and specificity of two questionnaires to identify patients with obstructive sleep apnea (OSA).Materials and methodsFifty-three moderate to severe OSA patients [with a respiratory disturbance index (RDI) ≥ 15] and 31 controls (RDI < 15) based on ambulatory somnographic assessment were recruited through flyers and mail at USC School of Dentistry. Each patient answered the Berlin and apnea risk evaluation system (ARES) questionnaires. The responses to the questionnaires were scored and compared for significant group differences.ResultsModerate and severe OSA patients were predominantly male, older, had a larger neck size, and larger body mass index than controls. There were no significant differences in race or ethnicity between the two groups. In this study, subjects having a “high risk” ARES questionnaire were 7.9 times as likely to have OSA as subjects with “low or no risk” score (p = 0.0002). The ARES questionnaire had a sensitivity of 90.6%, specificity of 43.2%, a positive predictive value (PPV) of 73.8%, and negative predictive value (NPV) of 73.7% compared to 67.9%, 54.8%, 72%, and 50%, respectively, for the Berlin questionnaire using a cut point of RDI ≥ 15.ConclusionsIn this specific patient group, not uncommon to the regular dental private practice, the ARES questionnaire performed better than the Berlin questionnaire with higher sensitivity, similar PPV, higher NPV, but lower specificity. The lower specificity could be explained in part because the ARES has been tailored to screen patients with an RDI ≥ 5, and our study included mostly mild to severe patients. In conclusion, in this specific group of subjects, the ARES questionnaire is a better choice than the Berlin questionaire; however, the Berlin questionnaire is publicly available and the ARES screener is proprietary.

Evaluation of the Reliability and Accuracy of Using Cone-beam Computed Tomography for Diagnosing Periapical Cysts from Granulomas

INTRODUCTION The purpose of this study was to evaluate the reliability and accuracy of cone-beam computed tomographic (CBCT) imaging against the histopathologic diagnosis for the differential diagnosis of periapical cysts (cavitated lesions) from (solid) granulomas. METHODS Thirty-six periapical lesions were imaged using CBCT scans. Apicoectomy surgeries were conducted for histopathological examination. Evaluator 1 examined each CBCT scan for the presence of 6 radiologic characteristics of a cyst (ie, location, periphery, shape, internal structure, effects on surrounding structure, and perforation of the cortical plate). Not every cyst showed all radiologic features (eg, not all cysts perforate the cortical plate). For the purpose of finding the minimum number of diagnostic criteria present in a scan to diagnose a lesion as a cyst, we conducted 6 receiver operating characteristic curve analyses comparing CBCT diagnoses with the histopathologic diagnosis. Two other independent evaluators examined the CBCT lesions. Statistical tests were conducted to examine the accuracy, inter-rater reliability, and intrarater reliability of CBCT images. RESULTS Findings showed that a score of ≥4 positive findings was the optimal scoring system. The accuracies of differential diagnoses of 3 evaluators were moderate (area under the curve = 0.76, 0.70, and 0.69 for evaluators 1, 2, and 3, respectively). The inter-rater agreement of the 3 evaluators was excellent (α = 0.87). The intrarater agreement was good to excellent (κ = 0.71, 0.76, and 0.77). CONCLUSIONS CBCT images can provide a moderately accurate diagnosis between cysts and granulomas.