Cone-beam tomography assessment of the condylar position in asymptomatic and symptomatic young individuals.

STATEMENT OF PROBLEM: Studies of the condyle-mandibular fossa relationship are common, although the role of this relationship in the development of a temporomandibular disorder remains controversial. PURPOSE: The purpose of this study was to quantitatively evaluate the condyle-mandibular fossa relationship in young individuals with intact dentitions and compare it to that between individuals with and without symptoms of temporomandibular disorder. MATERIAL AND METHODS: Volunteers were classified as asymptomatic (n=20) or symptomatic (n=20) according to research diagnostic criteria for temporomandibular disorders. Each participant underwent 2 cone beam-computed tomography scans of the middle and lower third of the face: 1 scan of the maximum intercuspation position and 1 of the centric relationship position. The distance between the condyle and mandibular fossa was measured on frontal and lateral images of the temporomandibular joint. The condylar position was compared across groups (asymptomatic, symptomatic) by using the Mann-Whitney U test (α=.05). Within each group, the condylar position was compared across maximum intercuspation and centric relationship positions by using the Mann-Whitney U test (α=.05). RESULTS: No statistically significant differences were found in condylar positions between centric relationships and maximum intercuspation in either asymptomatic or symptomatic young adults, and no significant differences were found between asymptomatic and symptomatic young adults. CONCLUSIONS: The condyle-mandibular fossa relationships of these young adults were similar in the centric relationships and maximum intercuspation positions when evaluated by computed tomography. The presence or absence of temporomandibular disorder was not correlated with the condyle position in the temporomandibular joint.

Cone-beam tomography assessment of condylar position discrepancy between centric relation and maximal intercuspation.

The magnitude of occasional discrepancies between the centric relation and maximal intercuspation positions remains a controversial subject. This study quantitatively evaluated the possible discrepancies in the condyle/mandibular fossa relationship between these positions using cone-beam computed tomography. Twenty young and asymptomatic volunteers were distributed equally into normal occlusion and Angle Class I, II and III malocclusion groups. They were submitted to one tomographic scan in maximal intercuspation and one in centric relation. Measurements were performed on lateral and frontal cuts of the patients' temporomandibular joints, and the data collected were compared using Student's t test at a significance level of 5%. The results showed that there were no statistically significant differences between the centric relation and maximal intercuspation positions in young and asymptomatic patients with practically intact dentitions using cone-beam computed tomography.

Cone-beam tomography assessment of condylar position discrepancy between centric relation and maximal intercuspation

The magnitude of occasional discrepancies between the centric relation and maximal intercuspation positions remains a controversial subject. This study quantitatively evaluated the possible discrepancies in the condyle/mandibular fossa relationship between these positions using cone-beam computed tomography. Twenty young and asymptomatic volunteers were distributed equally into normal occlusion and Angle Class I, II and III malocclusion groups. They were submitted to one tomographic scan in maximal intercuspation and one in centric relation. Measurements were performed on lateral and frontal cuts of the patients' temporomandibular joints, and the data collected were compared using Student's t test at a significance level of 5%. The results showed that there were no statistically significant differences between the centric relation and maximal intercuspation positions in young and asymptomatic patients with practically intact dentitions using cone-beam computed tomography.

Assessment in vitro of brushing on dental surface roughness alteration by laser interferometry.

Noncarious cervical lesions (NCCLs) are considered to be of multifactorial origin, normally associated with inadequate brushing. This study assessed the influence in vitro of simulated brushing on NCCL formation. Fifteen human premolars were submitted to brushing in the cementoenamel junction region, using hard-, medium- and soft-bristled brushes associated with a toothpaste of medium abrasiveness under a 200 g load, at a speed of 356 rpm for 100 minutes. The surface topography of the region was analyzed before and after brushing, by means of a laser interferometer, using "cut-off" values of 0.25 and considering roughness values in mm. The initial roughness (mm) results for dentin (D / bristle consistency: 1--soft, 2--medium and 3--hard) were as follows: (D1) 1.25 +/- 0.45; (D2) 1.12 +/- 0.44; (D3) 1.05 +/- 0.41. For enamel (E / bristle consistency: 1--soft, 2--medium and 3--hard), the initial results were: (E1) 1.18 +/- 0.35; (E2) 1.32 +/- 0.25; (E3) 1.50 +/- 0.38. After brushing, the following were the values for dentin: (D1) 2.32 +/- 1.99; (D2) 3.30 +/- 0.96; (D3) Over 500. For enamel, the values after brushing were: (E1) 1.37 +/- 0.31; (E2) 2.15 +/- 0.90; (E3) 1.22 +/- 0.47. Based on the results of the ANOVA and Tukey statistical analyses (a = .05) it was concluded that soft, medium and hard brushes are not capable of abrading enamel, whereas dentin showed changes in surface roughness by the action of medium- and hard-bristled brushes.

Assessment in vitro of brushing on dental surface roughness alteration by laser interferometry

Noncarious cervical lesions (NCCLs) are considered to be of multifactorial origin, normally associated with inadequate brushing. This study assessed the influence in vitro of simulated brushing on NCCL formation. Fifteen human premolars were submitted to brushing in the cementoenamel junction region, using hard-, medium- and soft-bristled brushes associated with a toothpaste of medium abrasiveness under a 200 g load, at a speed of 356 rpm for 100 minutes. The surface topography of the region was analyzed before and after brushing, by means of a laser interferometer, using "cut-off" values of 0.25 and considering roughness values in mm. The initial roughness (mm) results for dentin (D / bristle consistency: 1 - soft, 2 - medium and 3 - hard) were as follows: (D1) 1.25 ± 0.45; (D2) 1.12 ± 0.44; (D3) 1.05 ± 0.41. For enamel (E / bristle consistency: 1 - soft, 2 - medium and 3 - hard), the initial results were: (E1) 1.18 ± 0.35; (E2) 1.32 ± 0.25; (E3) 1.50 ± 0.38. After brushing, the following were the values for dentin: (D1) 2.32 ± 1.99; (D2) 3.30 ± 0.96; (D3) Over 500. For enamel, the values after brushing were: (E1) 1.37 ± 0.31; (E2) 2.15 ± 0.90; (E3) 1.22 ± 0.47. Based on the results of the ANOVA and Tukey statistical analyses (a = .05) it was concluded that soft, medium and hard brushes are not capable of abrading enamel, whereas dentin showed changes in surface roughness by the action of medium- and hard-bristled brushes.