Early detection of radiation-induced structural changes in rat trabecular bone

Hearing Performance in Cochlear Implant Users Who Have Facial Nerve Stimulation

Introduction  Facial nerve stimulation (FNS) is a complication in cochlear implant (CI) when the electrical current escapes from the cochlea to the nearby facial nerve. Different management to reduce its effects are available, although changes might result in a less-than-ideal fitting for the CI user, eventually reducing speech perception. Objective  To verify the etiologies that cause FNS, to identify strategies in managing FNS, and to evaluate speech recognition in patients who present FNS. Methods  Retrospective study approved by the Ethical Board of the Institution. From the files of a CI group, patients who were identified with FNS either during surgery or at any time postoperatively were selected. Data collection included: CI manufacturer, electrode array type, age at implantation, etiology of hearing loss, FNS identification date, number of electrodes that generated FNS, FNS management actions, and speech recognition in quiet and in noise. Results  Data were collected from 7 children and 25 adults. Etiologies that cause FNS were cochlear malformation, head trauma, meningitis, and otosclerosis; the main actions included decrease in the stimulation levels followed by the deactivation of electrodes. Average speech recognition in quiet before FNS was 86% and 80% after in patients who were able to accomplish the test. However, there was great variability, ranging from 0% in quiet to 90% of speech recognition in noise. Conclusion  Etiologies that cause FNS are related to cochlear morphology alterations. Facial nerve stimulation can be solved using speech processor programming parameters; however, it is not possible to predict outcomes, since results depend on other variables.

Assessment of bone quality of apical periodontitis treated with MTA plug and regenerative endodontic techniques

Fractal analysis (FA) is a quantitative, objective and non-invasive method that facilitates the characterisation of the tissue architecture. This study aims to compare the periapical healing at 1-year follow-up by evaluating newly generated trabecular bone with FA after Mineral trioxide aggregate (MTA) plug and regenerative endodontic treatment (RET). A total of 55 asymptomatic teeth with a single-canal, open apex and periapical lesion, treated with MTA plug or RET, were evaluated retrospectively. After considering the inclusion/exclusion criteria, FA was conducted on 30 periapical images using the box-counting method. In both groups, a significant decrease was observed in the periapical lesion size at 1-year follow-up (p < 0.01). However, there was no significant difference between the MTA plug and RET (p > 0.01). Significantly higher fractal dimension values were detected at 1-year follow-up in both MTA plug and RET cases (p < 0.01). However, the difference was not significant between the groups (p > 0.01). Both procedures seem to improve periapical healing with a new resistant bone of similar density and complexity.

High doses of ionizing radiation on bone repair: is there effect outside the irradiated site?

Local ionizing radiation causes damage to bone metabolism, it reduces blood supply and cellularity over time. Recent studies indicate that radiation promotes biological response outside the treatment field. The aim of this study was to investigate the effects of ionizing radiation on bone repair outside the irradiated field. Ten healthy male Wistar rats were used; and five animals were submitted to radiotherapy on the left femur. After 4 weeks, in all animals were created bone defects in the right and left femurs. Seven days after surgery, animals were euthanized. The femurs were removed and randomly divided into 3 groups (n=5): Control (C) (right femur of the non-irradiated animals); Local ionizing radiation (IR) (left femur of the irradiated animals); Contralateral ionizing radiation (CIR) (right femur of the irradiated animals). The femurs were processed and embedded in paraffin; and bone histologic sections were evaluated to quantify the bone neoformation. Histomorphometric analysis showed that there was no significant difference between groups C (24.6±7.04) and CIR (25.3±4.31); and IR group not showed bone neoformation. The results suggest that ionizing radiation affects bone repair, but does not interfere in bone repair distant from the primary irradiated site.

Low-level laser therapy on bone repair of rat tibiae exposed to ionizing radiation

OBJECTIVE

The purpose of this study was to evaluate the effects of low-level laser therapy (LLLT) on the repair of rat tibiae exposed to ionizing radiation (IR).

BACKGROUND DATA

IR causes structural changes that delay bone tissue repair. Properly dosed, LLLT improves the bone repair process.

METHODS

Seventy-two healthy Wistar rats were distributed into the following groups: Group I, sham control; Group II, LLLT; Group III, IR; and Group IV, IR and LLLT. Groups III and IV received a single dose (30 Gy) of gamma radiation and underwent surgery 28 days later. A noncritical sized bone defect (diameter 2.5 mm) was surgically created in all groups. Groups II and IV received three applications of postsurgical LLLT (GaAlAs, 808 nm, 100 mW, 0.028 cm(2), 3.57 W/cm(2), 20 sec, 2 J,≅71.4 J/cm(2)) on alternate days. Histomorphometry was assessed following digital image analysis.

RESULTS

The samples were evaluated on days 7, 14, and 21 after surgery; the IR protocol resulted in a significant reduction (p<0.018) in bone formation in Group III compared with Group I. Significant increases (p<0.006) in newly formed bone were noted in Group IV compared with Group III. No significant differences were observed between Group I and Group IV.

CONCLUSIONS

LLLT increased the newly formed bone area during the initial phase of the tibiae repair process in rats exposed to IR.

Histological analysis of the alterations on cortical bone channels network after radiotherapy: A rabbit study

The aim of this study was to evaluate the effects of radiotherapy in cortical bone channels network. Fourteen rabbits were divided in two groups and test group received single dose of 15 Gy cobalt-60 radiation in tibia, bilaterally. The animals were sacrificed and a segment of tibia was removed and histologically processed. Histological images were taken and had their bone channels segmented and called regions of interest (ROI). Images were analyzed through developed algorithms using the SCILAB mathematical environment, getting percentage of bone matrix, ROI areas, ROI perimeters, their standard deviations and Lacunarity. The osteocytes and empty lacunae were also counted. Data were evaluated using Kolmogorov-Smirnov, Mann Whitney, and Student's t test (P < 0.05). Significant differences in bone matrix percentage, area and perimeters of the channels, their respective standard deviations and lacunarity were found between groups. In conclusion, the radiotherapy causes reduction of bone matrix and modifies the morphology of bone channels network.

Fractal dimension analysis of periapical reactive bone in response to root canal treatment

OBJECTIVE

Mathematical morphology and box counting were used to extract trabecular pattern and to evaluate changes of reactive bone following root canal treatment.

STUDY DESIGN

Periapical radiographs were digitized and processed with mathematical morphology operations known as skeletonization. The trabecular patterns resulting from this skeletonization process were further analyzed with fractal dimension (FD) analysis using the box-counting method. Two groups of regions of interest (ROI) were selected from 19 subjects for the analysis.

RESULTS

Seventeen patients in one group and 13 patients in the other showed decreased FD in the reactive bone region after clinically successful root canal treatment (RCT). Significant changes in FD were noted 6 months after RCT (P < .05). Kappa analysis indicated significant reproducibility between the 2 groups of ROIs.

CONCLUSIONS

Mathematical morphology combined with box counting showed decrease of FD in reactive bone regions after clinically successful endodontic treatment.

Efeitos da radioterapia no tecido ósseo

OBJETIVO: Avaliar os efeitos da radioterapia e a acurácia da mensuração do nível de cinza do tecido ósseo em imagens radiográficas. MATERIAIS E MÉTODOS: Quatro ratos Wistar foram submetidos a radioterapia externa (dose única de 3.000 cGy) em uma área de 2 cm × 2 cm na perna direita. Os animais foram sacrificados seis semanas após a radioterapia, e tanto as pernas irradiadas quanto as contralaterais (não-irradiadas) foram avaliadas na sua espessura, radiografadas de forma padronizada e processadas histologicamente (hematoxilina-eosina e picrossírius). As radiografias foram digitalizadas e a média dos níveis de cinza foi mensurada no programa Image Tool®. RESULTADOS: A espessura do fêmur foi maior na perna contralateral do que na irradiada (p < 0,05). Radiograficamente, observou-se maior quantidade de tecido ósseo na perna contralateral em relação à perna irradiada, porém sem diferença estatística significante (p > 0,05). Histologicamente, foi possível observar, na perna irradiada, diminuição do número de osteócitos e dos canais de Havers, porém sem diferença estatística significante (p > 0,05). Por outro lado, foi observado aumento significante de adipócitos, com conseqüente diminuição de tecido medular na perna irradiada (p < 0,05) e maior atividade osteoblástica na perna contralateral (p < 0,05). CONCLUSÃO: A radioterapia, na dose aplicada, determinou diminuição da atividade de remodelação óssea, que pôde ser detectada radiograficamente na maioria dos espécimes avaliados.

Effect of Laser Therapy on Bone Tissue Submitted to Radiotherapy: Experimental Study in Rats

OBJECTIVE

The aim of this study was to investigate the effect of laser therapy (lambda = 780 nm) on bone tissue submitted to ionizing radiation.

BACKGROUND DATA

The biostimulation effect of laser in normal bone tissue has already been demonstrated successfully; however its effect on bone tissue submitted to radiotherapy has not yet been studied.

METHODS

Twenty-two Wistar rats were randomly divided into four groups: group I, control (n = 4), submitted only to radiotherapy; group II, laser starting 1 day prior to radiotherapy (n = 6); group III, laser started immediately after radiotherapy (n = 6); group IV, laser 4 weeks after radiotherapy (n = 6). The source of ionizing radiation used was Cobalt 60, which was applied in a single dose of 3000 cGy on the femur. The laser groups received seven applications with a 48-h interval in four points per session of DE = 4 J/cm(2), P = 40 mW, t = 100 sec, and beam diameter of 0.04 cm(2). All animals were killed 6 weeks after radiotherapy.

RESULTS

Clinical examination revealed cutaneous erosions on experimental groups (II, III, and IV) starting at the 6th week after radiotherapy. The radiographic findings showed higher bone density in groups II and IV (p < 0.05) compared to the control group. The results further showed an increase of bone marrow cells, and number of osteocytes and Haversian canals in experimental groups II and IV (p < 0.05). It was also found an increase of osteoblastic activity, in groups II, III, and IV (p < 0.05).

CONCLUSION

Laser therapy on bone tissue in rats presented a positive biostimulative effect, especially when applied before or 4 weeks after radiotherapy. However, the use of laser in the parameters above should be used with caution due to epithelial erosions.

Diagnostic criteria for the detection of mandibular osteomyelitis using cone-beam computed tomography

OBJECTIVES

To investigate the usefulness of cone-beam computed tomography (CBCT) in cases of suspected osteomyelitis (OM) of the mandible.

METHODS

13 patients with clinical suspected OM of the mandible underwent cone-beam computed tomography with the NewTom QR-DVT 9000. After CBCT revealed signs confirming the diagnosis of OM, biopsies were performed. Only cases in which histology confirmed the OM were included in this study.

RESULTS

CBCT sufficiently depicts OM-typical lesions like osteolytic and osteosclerotic areas as well as periosteal reaction, ill-defined cortical borders and sequestra.

CONCLUSIONS

Because the local extension of the disease and its relationship to anatomic structures can be sufficiently detected by CBCT, we see an important additional indication for the usage of CBCT. With regard to distinct cases CBCT combined with scintigraphy seems to be a sufficient diagnostic strategy concerning suspected OM.

Digital imaging analysis with mathematical morphology and fractal dimension for evaluation of periapical lesions following endodontic treatment

OBJECTIVE

To see if a method for digitizing trabecular pattern of bone could be used to quantitatively evaluate changes in bone pattern following endodontic treatment of teeth with periapical osteolytic lesions.

STUDY DESIGN

Periapical radiographs were digitized and further processed with mathematical morphology operations known as skeletonization. The trabecular patterns resulting from this skeletonization process were further analyzed with fractal dimension analysis using box-counting.

RESULTS

The periapical area in digitized radiographic images showed fractal behavior. Twenty-five of 27 patients showed increase of the fractal dimension after root canal treatment. Significant changes of the box-counting could be noted 3 months after root canal treatment (P < .05).

CONCLUSIONS

Mathematical morphology operation and box-counting might be helpful in early detection of changes of periapical trabecular pattern after root canal treatment.