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Biomedical subjects

Robert P Langlais

Publications and source records attributed to Robert P Langlais.

7 recordsLinked to original sources
PubMed2005

Image artifact in dental cone-beam CT.

PURPOSE: The purpose of this study was to investigate the appearance and possible cause of an artifact seen in limited-volume cone-beam CT imaging. METHODS: A water-filled plastic cylinder was used as a phantom of the head. A test object was constructed as a bone-equivalent phantom to be imaged. The test object was variously positioned at the center of the phantom and near its margins. CT images of the test object were acquired using a 3DX Accuitomo system. RESULTS: In slice images with the test object positioned near the margin of the phantom, arch-shaped defects or deformities were observed on the side of the object. There was a negative correlation between the artifact and the CT value of the object. The artifact was larger in images scanned with a higher voltage. CONCLUSION: The probability that this artifact is caused by halation from the image intensifier (II) system is suggested.

Artifacts↗
PubMed2005

Condylar head remodeling following mandibular setback osteotomy for prognathism: a comparative study of different imaging modalities.

PURPOSE: Condylar remodeling, which develops after mandibular setback osteotomy, was evaluated and compared in CT, plain film radiographs, and MR images acquired postoperatively. METHODS: Thirty-nine patients treated with sagittal split ramus osteotomy (SSRO) and 46 patients treated with intraoral vertical ramus osteotomy (IVRO) were studied. Remodeling as seen in the images and the diagnostic agreement between imaging modalities was evaluated. RESULTS: A newly formed bone layer in the posterior part of the condylar head was identified as a sign suggestive of remodeling. This sign was seen predominantly at periods over 6 months postoperatively. IVRO subjects had a higher incidence of remodeling than did the SSRO group. The diagnostic agreement between the 3 imaging modalities was substantial. There was a positive correlation between postoperative condylar displacement and the incidence of remodeling. CONCLUSIONS: The incidence of postoperative condylar head remodeling may be predictable. High-dose postoperative imaging studies to assess the TMJ should be restricted to those cases having a clear need for such studies.

Adolescent↗
PubMed2005

Geographic tongue: clinical characteristics of 188 cases.

The purpose of this study was to investigate the clinical characteristics and assess other factors associated with geographic tongue in Thailand. One hundred and eighty-eight Thais with geographic tongue and 188 controls were interviewed regarding their medical history, symptoms, and the nature and migratory pattern of their lesions. Variations in the clinical appearance, lesion location, and any associated tongue fissures were recorded. The age range for the 188 subjects was 9 to 79 years. The highest incidence (39.4%) occurred in the 20-29 age group. Women were affected more than men (1.5:1). The leading group of medical conditions consisted of allergy-related disorders; however, the incidence of these problems among both subjects and controls was not significantly different (55.2% vs. 44.8%). Our results demonstrated a significant co-existence of geographic tongue and fissured tongue. Most of the geographic tongue lesions manifested a typical appearance consisting of a central atrophic area bounded by a raised white circinate line (69.1%) with multiple tongue sites affected (62.8%). The most common locations were at the lateral margins and tip of the tongue. The majority of our subjects (75.5%) were asymptomatic. The results of this study correspond with the findings of previous geographic tongue studies in other populations.

Adolescent↗
PubMed2005

3D-CT evaluation of facial asymmetry.

OBJECTIVE: Recently, 3-dimensional-computed tomography (3D-CT) imaging has been used in the diagnosis and surgical treatment planning of patients with craniofacial deformities. The present authors have developed a 3D-CT imaging procedure for a 3-dimensional coordinate point evaluation system to assess and diagnose patients with facial asymmetry. STUDY DESIGN: The CT data of 16 subjects was selected retrospectively as the control group from patients who had undergone CT examinations to diagnose conditions other than maxillofacial deformities. Anatomical landmarks modified from orthodontic craniometric (cephalometric) points were defined on the 3D-CT images and the asymmetry index of each point was calculated in millimeters. A diagrammatic chart with a baseline indicating the mean asymmetry indices plus the standard deviation in the control group was designed. The resulting diagrammatic chart was used to evaluate the degree of deformity in facial asymmetry patients. RESULTS AND CONCLUSIONS: The topography of facial asymmetry was assessed. The 3D-CT imaging technique as described herein is a practical method of evaluating the morphology of facial asymmetry.

Adolescent↗
PubMed2004

Medical health and medication use in elderly dental patients.

The objectives of this study were to obtain information on the medical conditions and medications used among elderly Thai dental patients and to investigate the relationship between the findings in relation to age and sex. The information regarding medical conditions and medication use was obtained from interviews of 510 dental patients aged 60 years and older. The incidence of medical conditions was 82.5%; women had a significantly higher incidence of medical conditions (86.5%) than men (76.5%). The incidence of medical conditions did not differ among the three age groups. Overall, cardiovascular disease was the leading problem (33.7%) with hypertension being the major component (26.1%). The prevalent problems were bone/joint disorders (32.4%), allergies (18.2%), diabetes mellitus (14.5%), and eye and ear problems (14.3%). In our sample, 65.5% reported taking medications, with an average of 1.5 drug groups per person. The average number of medications taken increased as age increased. Women took medications more frequently than men (70% vs. 58.5%). The four most prevalent drugs were cardiovascular agents (32%), endocrinologic drugs (14.5%), nutritional therapeutics (12.9%), and drugs acting on the musculoskeletal system (11.4%). The present study supports the findings of previous reports in that the presence of medical conditions is high in the elderly and the incidence of medication use increases with advancing age.

Age Factors↗
PubMed2004

3D CT evaluation of masseter muscle morphology after setback osteotomy for mandibular prognathism.

OBJECTIVE: Following mandibular setback osteotomy, changes in the direction, length, and cross-sectional area of the masseter muscle were studied by means of computerized tomography (CT) images generated with a 3-dimensional (3D) reconstructive technique. STUDY DESIGN: Pre- and postoperative CT examinations were performed on 17 prognathic patients treated by sagittal split ramus osteotomy with rigid osteosynthesis and 13 patients treated by intraoral vertical ramus osteotomy without osteosynthesis. The pre- and postoperative masseter muscle direction and length were evaluated using 3D CT images observed from a lateral viewing angle. The cross-sectional area of the masseter muscle was first measured on an axial CT image of a selected slice level, following which the right-angle cross-sectional area of the muscle was revised using the measured area from the axial image. RESULTS: Postoperatively, anterior tilting of the masseter muscle was observed; however, masseter muscle length was unchanged. Three months postoperatively, a significant reduction in the cross-sectional area of the masseter muscle was seen. A tendency to revert back to the normal dimension was seen between 6 months and 1 year postoperatively. No significant difference was noted between the 2 surgical techniques. CONCLUSIONS: Three-dimensional computed tomography is an adequate imaging modality for masseter muscle evaluation. The results of this study suggest the masseter muscle may undergo reversible atrophy after mandibular setback osteotomy.

Adolescent↗