Orthodontists' and parents' perception of finished occlusion and willingness to extend treatment time.

INTRODUCTION: Patients and parents want shorter treatment times, but it is unclear whether they would compromise outcome quality to shorten treatment. The purpose of this study was to compare orthodontists' and parents' perceptions of finished occlusion and their willingness to extend treatment time to achieve improved outcomes. The effects of elapsed treatment time and patient compliance were also investigated. METHODS: Parallel surveys for orthodontists (n = 1000) and parents (n = 750) displayed simulated treatment outcomes of well-aligned teeth with occlusions in 1 mm increments from 3 mm Class III to 3 mm Class II. Participants rated their preferences on a visual analogue scale (VAS; 0-100) and specified whether they would extend treatment, and for how long, to improve the occlusion. RESULTS: Two hundred thirty-three orthodontists (23%) and 243 parents (32%) responded. Despite differences between the scores given (P < 0.0001), both groups rated Class I occlusion most acceptable (mean VAS = 93.9 and 80.7, respectively) and 3 mm Class III malocclusion least acceptable (mean VAS = 25.9 and 40.9, respectively). Parents were willing to extend treatment more often and for a greater time than orthodontists to improve results (P < 0.0001). In addition, parents were less willing to terminate treatment early (P < 0.05). Both groups perceived existing outcomes as more acceptable if the patient was noncompliant (P < 0.05), but elapsed time in treatment had no significant effect on ratings. CONCLUSIONS: For outcomes with well-aligned teeth, orthodontists and parents agreed on what the most and least acceptable occlusal relationships were. To achieve better outcomes, parents were willing to extend treatment duration more often and for a greater time than were orthodontists. In addition, parents were less willing than orthodontists to terminate treatment early.

Assessment of CT numbers in limited and medium field-of-view scans taken using Accuitomo 170 and Veraviewepocs 3De cone-beam computed tomography scanners.

PURPOSE: To assess the influence of anatomic location on the relationship between computed tomography (CT) number and X-ray attenuation in limited and medium field-of-view (FOV) scans. MATERIALS AND METHODS: Tubes containing solutions with different concentrations of K2HPO4 were placed in the tooth sockets of a human head phantom. Cone-beam computed tomography (CBCT) scans were acquired, and CT numbers of the K2HPO4 solutions were measured. The relationship between CT number and K2HPO4 concentration was examined by linear regression analyses. Then, the variation in CT number according to anatomic location was examined. RESULTS: The relationship between K2HPO4 concentration and CT number was strongly linear. The slopes of the linear regressions for the limited FOVs were almost 2-fold lower than those for the medium FOVs. The absolute CT number differed between imaging protocols and anatomic locations. CONCLUSION: There is a strong linear relationship between X-ray attenuation and CT number. The specific imaging protocol and anatomic location of the object strongly influence this relationship.

Influence of anatomical location on CT numbers in cone beam computed tomography.

OBJECTIVE: To assess the influence of anatomical location on computed tomography (CT) numbers in mid- and full field of view (FOV) cone beam computed tomography (CBCT) scans. STUDY DESIGN: Polypropylene tubes with varying concentrations of dipotassium hydrogen phosphate (K2HPO4) solutions (50-1200 mg/mL) were imaged within the incisor, premolar, and molar dental sockets of a human skull phantom. CBCT scans were acquired using the NewTom 3G and NewTom 5G units. The CT numbers of the K2HPO4 phantoms were measured, and the relationship between CT numbers and K2HPO4 concentration was examined. The measured CT numbers of the K2HPO4 phantoms were compared between anatomical sites. RESULTS: At all six anatomical locations, there was a strong linear relationship between CT numbers and K2HPO4 concentration (R(2)>0.93). However, the absolute CT numbers varied considerably with the anatomical location. CONCLUSION: The relationship between CT numbers and object density is not uniform through the dental arch on CBCT scans.