Regional differences in microarchitecture and mineralization of the atrophic edentulous mandible: A microcomputed tomography study

The Effect of General Bone Mineral Density on the Quantity and Quality of the Edentulous Mandible: A Cross-Sectional Clinical Study

BACKGROUND

Osteoporosis is a disease which is characterized by a decrease in general bone mineral density (BMD), resulting in decreased bone strength and an increased risk of bone fractures. The effect of reduced BMD on the jawbones is still not fully understood. The purpose of the study was to evaluate the impact of BMD on the quality and quantity of the edentulous mandible.

METHODS

The present study included 127 edentulous postmenopausal women who underwent cone beam computed tomography (CBCT) examinations. BMD measurements of the lumbar spine and femoral necks were performed by dual-energy X-ray absorptiometry. In the cross-sectional CBCT images, three different areas of the mandible (lateral incisor, first premolar, and first molar) were selected. The complete mandibular, trabecular, and cortical bone volumes were measured. All measurements were performed on the total mandibular area, and the basal and alveolar parts of the mandible.

RESULTS

The volume of the cortical bone was reduced for females with reduced BMD in the lateral incisor and first premolar regions, both in the total mandibular area and in the basal part of the mandible. The trabecular bone volume statistically significantly increased when the BMD decreased in the complete mandibular area and the basal part of the mandible (linear regression). The total bone volume significantly decreased with a decrease in BMD in the basal part of the mandible.

CONCLUSIONS

Reduced BMD has a negative effect on the quantity and quality of bone in the basal part of the edentulous mandible.

Assessment of Bone Mineral Density in Type 2 Diabetes: A Cone Beam Computed Tomography (CBCT) Study

Introduction

The main purpose of the study was to assess and compare bone mineral density (BMD) at prospective implant sites in the mandible in type 2 diabetes mellitus (T2DM) and non-diabetic patients using cone beam computed tomography (CBCT).

Material and methodology

A total of 40 patients were included in this type of cross-sectional study. They were divided into two groups, A and B, according to their haemoglobin A1c values. Group A consisted of patients with HbA1c between the range of 6.1%-8% and group B had patients with no history of T2DM. CBCT scans were made of the mandibular arches of both the patients to evaluate the BMD at lingual and buccal cortical plates and the trabecular regions in two successive slices with the assistance of PlanMeca Romexis software (PlanMeca Romexis®, Helsinki, Finland). The Shapiro-Wilk test was used to determine the normality of continuous data. The Mann-Whitney U test was used to compare the groups.

Results

There were no differences that were statistically significant between the two cohorts according to the Mann-Whitney U test at buccal cortical plate points 1 and 2. However, the diabetes group's mean bone density at implant sites-A, B, C, D, and E at trabeculae points 1 and 2 was considerably (7p>0.001) lower than the non-diabetic groups. The mean bone density of the diabetes group was marginally but significantly (p=0.009) lower than the non-diabetic group at lingual cortical plates.

Conclusion

Individuals with type 2 diabetes mellitus show significantly lower bone mineral density in the lingual cortical plate and trabecular region, however, implant therapy can be performed with certain mentioned guidelines in such regions. In the buccal cortical region, the bone mineral density is seen to be unaffected.

Temperature Changes during Implant Osteotomy Preparations in Fresh Human Cadaver Tibiae, Comparing Straight with Tapered Drills

The success of osseointegration depends on many factors. With temperatures beyond a 47 °C threshold over 1 min, bone survival may be impaired. The purpose of the study was to evaluate, in fresh human cadaver tibiae, the temperature changes during osteotomy preparations using two straight and two tapered implant systems’ drills, external irrigation, and varying revolutions per minute (RPM). The tibiae from a fresh female cadaver were harvested bilaterally. Two tapered and two straight design drills were assessed. Two-hundred and forty osteotomies were prepared at 6 mm depth following the drill sequence of the manufacturers’ protocol for each drilling speed. Difference in temperature (ΔΤ) was calculated by subtracting the baseline from the maximum temperature (ΔT = T_max − T_base). Drill design and drill diameter, as independent variables or synergistically, had a significant effect on ΔΤ. Tapered drills: As the drill diameter increased, ΔΤ increased at all RPM. Straight drills: As the drill diameter increased, ΔΤ remained constant or slightly decreased at all RPM. Drill diameter and design had a significant effect on ΔΤ in human tibiae, which never exceeded the critical threshold of 47 °C. Tapered drills caused significantly greater heat production compared to straight drills.