Celia Regina Winck Mahl

Comparação de índices morfométricos obtidos na radiografia odontológica panorâmica na identificação de indivíduos com osteoporose/osteopenia

OBJECTIVE: The present study was aimed at comparing indices obtained from dental panoramic radiographs with bone densitometry results in the identification of individuals affected by osteoporosis/osteopenia. MATERIALS AND METHODS: Panoramic mandibular, mental, antegonial, gonial and mandibular cortical indices calculated with basis on dental panoramic radiographs of postmenopausal women were compared with bone densitometry results, twice by one observer and once by a second observer. RESULTS: Significant differences were not found between the two measurements performed by the same observer, except for the antegonial index on the left side. Interobserver agreement for both sides was good. The variance analysis demonstrated statistically significant differences among groups (normal, osteopenia and osteoporosis) for all the indices evaluated. Differences were significant among all mean panoramic mandibular and mental indices. On the other hand, for the antegonial and gonial indices, only the normal group presented higher means as compared with the other groups (osteopenia and osteoporosis) which did not differ between themselves. CONCLUSION: The indices evaluated were reproducible; panoramic mandibular and mental indices presented the highest sensitivity in the detection of osteopenia/osteoporosis, however the panoramic mandibular index specificity was low. Although all the indices evaluated could identify low bone density, only the panoramic mandibular and mental indices could differentiate patients affected by osteopenia/osteoporosis.

Evaluation by digital subtraction radiography of induced changes in the bone density of the female rat mandible.

OBJECTIVES To verify whether changes in bone mass induced by glucocorticoid and bisphosphonate can be detected by digital subtraction radiography of lateral X-rays in female rat mandibles. METHODS 36 Rattus norvegicus (Wistar) females were randomly allocated to three groups: Group 1, control (n = 12); Group 2, induced osteopaenia (n = 12); and Group 3, induced osteopaenia plus risedronate (n = 12). Group 1 received subcutaneous saline solution (2 ml kg(-1)) injections for 12 weeks. Group 2 received 1 mg kg(-1) methylprednisolone acetate for 12 weeks. Group 3 received the same treatment as Group 2, plus 3 mg kg(-1) risedronate sodium for a further 12 weeks. A radiograph of the left mandible was taken on day 0 and after 12 weeks. A third radiograph was taken in Group 3 after risedronate treatment. Digital subtraction of the radiographs was used to compare the intensity of pixels in the control area and the test area. The animals were killed and the same area assessed by subtraction was histologically evaluated. RESULTS ANOVA revealed statistically significant histological differences between the three groups. Tukeys multiple comparisons test showed that Group 2 had the smallest mean proportion of bone trabeculae per field and Group 3 the largest (F = 37.56; P < 0.01). Radiographic subtraction revealed a higher mean pixel intensity in Groups 1 and 3 vs Group 2. In Group 3, glucocorticoid caused a significant loss in radiographic density, and risedronate restored that loss (Friedmans non-parametric test). CONCLUSIONS Subtraction radiography was able to detect changes in bone mass induced by glucocorticoid and bisphosphonate.

Optimal parameters for lateral oblique radiographs of rat mandibles

OBJECTIVE To establish optimal exposure parameters for lateral oblique radiographs of rat mandibles using an intraoral X-ray machine. METHODS A positioning apparatus, previously tested for its reproducibility, was used to obtain radiographs of four heads of formaldehyde-preserved Wistar rats. Radiographs were exposed at 50 kV and 8 mA using four size 2 films (Insight, Ektaspeed Plus, Ultraspeed and D-Speed; Eastman Kodak Co., Rochester, NY), two focal distances (30 cm and 60 cm) and seven exposure times (0.6 s, 0.7 s, 0.8 s, 1.0 s, 1.5 s, 2.0 s and 2.5 s). The radiographs were evaluated by two examiners and scored for image quality: 1, very poor; 2, poor; 3, fair; 4, good; and 5, excellent. The evaluations were repeated at 30 days. RESULTS Intraobserver reproducibility was substantial (kappa = 0.798 and 0.667). Also, the two examiners showed substantial agreement (kappa = 0.726). There was a significant difference (alpha = 1%) between the scores for the films under study. At a 30 cm distance, E-speed films had mean scores of 4 and 5 at 0.8 s and 1 s exposure times, and D-speed films, at 1.5 s, 2 s and 2.5 s exposure times. At a 60 cm distance, the best results were found for E-speed films at 2.0 s and 2.5 s exposure times. CONCLUSION The films under study did not show any significant difference in the quality of rat mandible images as long as exposure times were adequate to their sensitivity and focal distance.