Recombinant human MMP-2 associated with monoolein improves bone repair

OBJECTIVE

The main objective of the present study was to investigate the possible osteostimulatory action of recombinant human matrix metalloproteinase-2 (rhMMP-2) implanted in a bone defect made in calvaria of rats, bounded to the monoolein as carrier.

METHODS

Forty-four adult male Wistar rats (about 600 g body weight) underwent surgery in order to create a spherical defect in parietal bone on the right side of the median sagittal suture by using 4 mm diameter of a trephine drill. Animals were divided into three groups: no treatment (control, C), treatment with rhMMP-2 diluted in monoolein liquid crystal (rhMMP-2) and negative control with monoolein (M). The groups were divided into two experimental times, 2- and 4-weeks of experimental time.

RESULTS

The rate of new-formed bone, estimated by the number of points on new-formed cancellous bone, was in enhanced rhMMP-2 group in both periods in comparison to C or M groups.

CONCLUSION

There was no difference in bone neoformation between second to fourth week within groups. In the present study, monoolein alone had a negative role in the post-operative surgery, but monoolein associated with +rhMMP-2 had a positive role on releasing rhMMP-2 and enhance the rate of new-formed bone (Tab. 1, Fig. 5, Ref. 71).

Effects of high-impact exercise on the physical properties of bones of ovariectomized rats fed to a high-protein diet

The aim of this study was to evaluate the effects of high-impact physical exercise as a prophylactic and therapeutic means in osteopenic bones of rats submitted to ovariectomy and protein diet intake. A total of 64 Wistar rats were divided into eight groups (n = 8 each), being: OVX, ovx, standard diet and sedentary; OVXE, ovx, standard diet and jump; OVXP, ovx, high-protein diet and sedentary; and OVXEP, ovx, high-protein diet and jump; SH, sham, standard diet and sedentary; SHE, sham, standard diet and jump; SHP, sham, high-protein diet and sedentary; and SHEP, sham, high-protein diet and jump. OVX surgery consists of ovariectomy, and sham was the control surgery. The jumping protocol consisted of 20 jumps/day, 5 days/week. The bone structure was evaluated by densitometry, mechanical tests, histomorphometric, and immunohistochemical analyses. A high-protein diet resulted in increased bone mineral density (P = .049), but decreased maximal load (P = .026) and bone volume fraction (P = .023). The benefits of physical exercise were demonstrated by higher values of the maximal load in the trained groups compared to the sedentary groups (P < .001). The sham groups had decreased immunostaining of osteocalcin (P = .004) and osteopontin (P = .010) compared to ovx groups. However, the high-protein diet (P = .005) and jump exercise (P = .017) resulted in lower immunostaining of osteopontin compared to the standard diet and sedentary groups, respectively. In this experimental model, it was concluded that ovariectomy and a high-fat diet can negatively affect bone tissue and the high-impact exercise was not enough to suppress the deleterious effects caused by the protein diet and ovariectomy.

Influence of treadmill training on bone structure under osteometabolic alteration in rats subjected to high-fat diet

Nutrition and physical training have important roles in the accumulation and maintenance of bone mass. The aim of this study was to evaluate, in ovariectomized rats (OVX), the effects of treadmill training (T) with high-fat diet (F) on weight gain and bone tissue properties with eight groups (n = 10) for 12 weeks: OVX SC (OVX, sedentary lifestyle, diet control); OVX SF; OVX TC; OVX TF; SH SC (SHAM, sedentary lifestyle, diet control); SH SF; SH TC; and SH TF. Weekly weight gain and final body composition were assessed. After euthanasia, tibiae were analyzed. The trained animals had higher body weight (P = 0.001), bone mineral density (P < 0.001), and trabecular bone (P < 0.001). The animals with a high-fat diet showed higher global fat (P < 0.001), percentage of global fat (P < 0.001) and deformation at impact (P = 0.031) and reduced tibial bone mineral content (P = 0.036). Physical training improves bone microarchitecture, without presenting an increase in impact resistance, and a high-fat diet increases body fat and impairs bone mineralization.

Radiographical evaluation of bone quality after extraction of mandibular impacted and semi-impacted third molars

AIM

The association between bone quality and fracture risk in the mandibular angle with the presence of impacted/semi-impacted third molars and after their extraction is controversial. This study aimed to assess mandibular bone quality in digital radiographies of patients after extraction of impacted/semi-impacted lower third molars.

METHODS

A total of 130 sets of digital panoramic radiographies were selected and divided into the following three groups: Group 1 with 50 panoramic radiographies of patients with impacted/semi-impacted lower third molars, Group 2 with 30 panoramic radiographies of patients with lower third molar agenesis, and Group 3 with 50 panoramic radiographies of patients after extraction of impacted/semi-impacted lower third molars. The mandibular angular cortex was the anatomical structure used as parameter for bone quality assessment. ANOVA and Student's t test were applied for comparison between groups.

RESULTS

Mandibular angular cortical width was significantly lower when the third molar was present in both genders (P<0.05). Agenesis of the third molar in women was associated with lower thickness of the mandibular cortex when compared with patients who had their third molar extracted (P<0.05).

CONCLUSION

It can be concluded that the absence of impacted/semi-impacted lower third molars, was associated with a significant increase in cortical width.

Elongated styloid process and atheroma in panoramic radiography and its relationship with systemic osteoporosis and osteopenia

Association between the presence of an elongated styloid process, vascular calcification (atheroma) and the potential risk factor for osteoporosis was studied. Presence of an elongated styloid process was found to be correlated with systemic osteoporosis and also between elongated styloid process and atheroma.

INTRODUCTION

The association between the presences of an elongated styloid process and vascular calcification (atheroma) with the potential risk factor assessment for osteoporosis was studied.

METHODS

Bone mineral density obtained by dual energy X-ray absorptiometry diagnosed osteopenia/osteoporosis on at least two of three sites (column, hips, and forearm) of 50 female patients. Panoramic maxillomandibular radiographs were taken and analyzed. Elongation of the styloid processes was measured and the presence of atheromas in the carotid was investigated.

RESULTS

Eighty percent of the patients presented at least one side with elongated styloid process and the highest prevalence (87.5%) occurred in individuals between 60 and 69 years. Atheroma was found in four patients, three of which presented elongated styloid on at least one side and had diagnosed osteoporosis on at least two of the evaluated sites.

CONCLUSIONS

Correlation was found between the elongation of the styloid process and systemic osteoporosis, and between elongated styloid process and atheroma. The method in this study might be used as part of a method for osteopenia/osteoporosis and atheroma risk assessment.

Ageing and surface EMG activity patterns of masticatory muscles

The purpose of this study was to evaluate the influence of age on the electromyographic activity of masticatory muscles. All volunteers were Brazilian, fully dentate (except for Group I - mixed dentition), Caucasian, aged 7-80, and divided into five groups: I (7-12 years), II (13-20 years), III (21-40 years), IV (41-60 years) and V (61-80 years). Except for Group V, which comprised nine women and eight men, all groups were equally divided with respect to gender (20 M/20 F). Surface electromyographic records of masticatory muscles were obtained at rest and during maximal voluntary contraction, right and left laterality, maximal jaw protrusion and maximal clenching in the intercuspal position. Statistically significant differences (P < 0.05) were found in all clinical conditions among the different age groups. Considerably different patterns of muscle activation were found across ages, with greater electromyographic activity in children and youth, and decreasing from adults to aged people.

Histological and histomorphometrical alterations of the periodontal ligament in gerbils submitted to teeth extraction

This study verified the effect of unilateral teeth extraction on the periodontal ligament in gerbils (Meriones unguiculatus). Ten adult male gerbils weighing about 50 g had induced occlusal alterations by upper left molar extractions while the other ten animals, only submitted to surgical stress, were considered as controls. The periodontal ligament was characterized by qualitative and quantitative analysis, histological description and histomorphometric quantification. Significant alterations were observed on the left side of the experimental group (P < 0.05), the hypofunctional region, when it was compared with the contralateral side and the corresponding region of the control group. Two months after occlusal alterations induced by unilateral teeth extraction, atrophic histological alterations and a decrease in the periodontal space on the ipsilateral side characterized the periodontal ligament. In this study it was possible to conclude that the gerbil can be used in experimental models attempting to correlate the periodontium's biological response to various mechanical stresses, as the periodontal ligament was shown to be highly sensitive to occlusal alterations.

Electromyographical analysis of the masseter muscle in dentulous and partially toothless patients with temporomandibular joint disorders

This study had as objective to analyze with computerized electromyography the masseter muscles bilaterally in twenty individuals with temporomandibular joint dysfunction (DTM), being: the group I consisting of ten individuals with complete dentition and group II constituted by ten individuals with posterior dental absences; comparing nine clinical activities: rest before and after exercises, maximum habitual intercuspation (MIH), right and left laterality, forced centric occlusion, protrusion, bilateral molar bite and chewing. It was utilized the Electromyography K6I-Myotronics, with eight canals and surface silver electrodes. By means of the results analysis, we verified significant differences between the groups (p < 0.01), being group I, presented greater electromyographic activity (32.98 microvolts), than the group II (22.31 microvolts), suggesting that this individuals presented low muscular activity. The interaction between the groups and the clinical activities was significant (p < 0.01), as well as between the groups, clinical activities and muscles (p < 0.05). To clarify which amongst the relative averages the clinical activities were different, calculated the critical value of Tukey, being that rest before and after exercises, MIH, right and left laterality, presented averages with similar distributions, with values below of the values of Tukey, as well as forced centric occlusion, protrusion, bilateral molar bite and chewing presented higher values than Tukey. Based on this research's data, we concluded that the electromyographical analysis of the masseter muscles in Individuals with TMD, dentulous and with dental absence showed that individuals with TMD, dentulous or not, presented elevated muscular activity in rest position and individuals with TMD, dentulous, presented higher electromyographical activity than the individuals with TMD and lacking posterior teeth.