Conditioned fear stress increases bone resorption in apical periodontitislesions in Wistar male rats.

OBJECTIVE: Because the impact of conditioned fear stress on apical bone resorption is unknown, the aim of the current studywas to use a rat model to evaluate the impact of conditioned fear stress on the bone resorption of inflammatory apical periodontitis lesions. METHODS: Twenty-five animals were divided into two groups. They underwent a surgical procedure in the first left lower molar tooth to expose the dental pulp and induce inflammatory apical periodontitis lesions through the retention of contamination (bacterial infection) during a 56-day period. The animals in the case group were stressed daily by using electrical stimuli (1.10 mA), whereas the animals in the control group were absent from the stressful stimuli (shocks). The open field test was performed to validate the stress methodology. The jaws were removed and collected for histological and radiographic analyses. RESULTS: Stressed animals presented increased levels of bone loss and inflammatory cells in the root apex in comparison with the control group (P = 0.0001). However, no radiographic differences were observed between the groups (P > 0.05). CONCLUSIONS: Our results demonstrated that conditioned fear stress could modify a periapical lesion by increasing the size of bone loss there. Conditioned fear stress also increased the total number of inflammatory cells compared with the control group. Studies evaluating the impact of conditioned fear stress on human periapical inflammatory lesions should be encouraged.

Masticatory function parameters in patients with varying degree of mandibular bone resorption.

PURPOSE: This cross-sectional study analyzes how bone resorption affects the masticatory function and investigates the relation between perceived and measured masticatory function. METHODS: Thirty complete dentures wearers were divided in two groups according to mandible bone atrophy based on the classification criteria from Cawood & Howell. Retention and stability of the mandibular complete denture, masticatory performance (MP) indexes (X_50 and B) and masticatory efficiency (ME, sieves 4 and 2.8) were evaluated. Geriatric Oral Health Assessment Index (GOHAI) and Dental Impact on Daily Living (DIDL) questionnaires were completed by the patients. RESULTS: A strong correlation between bone atrophy and poor retention was found (P=0.0132). Neither masticatory performance indexes nor GOHAI and DIDL domains showed statistical differences (P>0.05) when patients were compared according to the atrophy criteria. Mandibular length showed a negative correlation with ME4, showing a positive association (R2=0.17, ß=-0.67, P=0.029). Mandibular denture retention was significantly correlated with MPB (P=0.01) and ME2.8 (P=0.01). GOHAI showed a positive association between the physical and the functional domains and ME2.8 (R2=0.17; ß=1.22; P=0.02). DIDL showed a negative association between ME4 and oral comfort domain (R2=0.16; ß=-2.94; P=0.02). CONCLUSION: Mandibular bone height does not directly affect the masticatory function and is inversely correlated with the self-perceived masticatory ability.

Identifying genes that regulate bone remodeling as potential therapeutic targets.

Bone remodeling, a coupled process involving bone resorption and formation, is initiated by mechanical signals and is controlled by local and systemic factors that regulate osteoblast and osteoclast differentiation and function. An excess of resorption over formation leads to the bone loss and increased propensity to fracture that is characteristic of osteoporosis. A newly described inhibitor of osteoblast differentiation, Ciz, interferes with bone morphogenic protein signaling. As a consequence, Ciz-deficient mice develop increased bone mass.

Effect of pamidronate on skeletal morbidity in myelomatosis. Part 1. The results of the first 12 months of pamidronate therapy.

BACKGROUND: Osteolytic bone destruction caused by increase of osteolytic activity is a major manifestation of multiple myeloma (MM). Pamidronate (3-amino-1-hydroxypropylidene)-1,1-bisphosphonate) inhibits osteoclastic activity and reduces bone resorption. METHODS: Since October 1995 the efficacy of pamidronate is evaluated in MM patients all receiving anti-myeloma chemotherapy acc. to VMCP/VBAP alternating regimen. 46 patients with stage III myeloma and osteolytic lesions were randomized to receive either pamidronate (Aredia; Novartis) 60 mg i.v. in 4-hour infusion monthly (n = 23) or chemotherapy alone (control group n = 23). Estimation of performance status, quality of life, pain score, analgesic consumption, serum calcium concentration and twenty four-hours Calcium excretion, urine Calcium/creatinine ratio is done at least once a month (before pamidronate administration) while X-ray skeletal survey--before treatment and then every six months. RESULTS: In the first months of treatment apparent reduction of bone pain occurred. Hypercalcaemia was revealed in 6 patients at entry into the study. In 5 of these patients pamidronate restored and maintained normocalcaemia for a median 6 months. In 3 patients an aggressive plasma cell proliferation was accompanied by reoccurrence of hypercalcaemia. At skeletal X-ray examination performed after 6 and 12 cycles of pamidronate and by comparing each of consecutive imaging with previous one the progression of osteolysis was respectively found in 67% and 39% of patients. In the control group corresponding figures were: 79% and 70%. The mean number of skeletal events (pathologic fracture, radiation to bone and spinal cord compression) per year was lower in the pamidronate group (1.82) than in control-patients (2.72), p < 0.013. The proportion of patients who developed skeletal event (excluding vertebral fractures) was lower in the pamidronate group -34% v 52%. Adverse events of pamidronate: hypocalcaemia (< 2 mmol/l) observed in 7 patients occurred in particular patients beginning from 2 to 7 days after drug administration. In 2 patients hypocalcaemia that appeared in 24 hours after drug infusion was accompanied by blood pressure decrease; in one case systolic blood pressure dropped up to 60 mmHg, in the other one--to 90 mmHg. Muscular pain and fever up to 39 degrees C (transient and self-limiting "influenza like syndrom") occurred in 5 patients, in two patients after several hours and in three other--after some dozens of hours from drug administration. In one case hypertransaminasaemia was observed. CONCLUSIONS: In the first year of treatment monthly intravenous pamidronate administration as an adjunct to chemotherapy in patients with advanced multiple myeloma with osteolysis is an efficient approach in prevention and treatment of hyperacalcaemia, hypercalciuria and bone pain. It also shows some preventive effect on bone lesion occurrence.