Biological and osseointegration capabilities of hierarchically (meso-/micro-/nano-scale) roughened zirconia.

PURPOSE: Zirconia is a potential alternative to titanium for dental and orthopedic implants. Here we report the biological and bone integration capabilities of a new zirconia surface with distinct morphology at the meso-, micro-, and nano-scales. METHODS: Machine-smooth and roughened zirconia disks were prepared from yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), with rough zirconia created by solid-state laser sculpting. Morphology of the surfaces was analyzed by three-dimensional imaging and profiling. Rat femur-derived bone marrow cells were cultured on zirconia disks. Zirconia implants were placed in rat femurs and the strength of osseointegration was evaluated by biomechanical push-in test. RESULTS: The rough zirconia surface was characterized by meso-scale (50 µm wide, 6-8 µm deep) grooves, micro-scale (1-10 µm wide, 0.1-3 µm deep) valleys, and nano-scale (10-400 nm wide, 10-300 nm high) nodules, whereas the machined surface was flat and uniform. The average roughness (Ra) of rough zirconia was five times greater than that of machined zirconia. The expression of bone-related genes such as collagen I, osteopontin, osteocalcin, and BMP-2 was 7-25 times upregulated in osteoblasts on rough zirconia at the early stage of culture. The number of attached cells and rate of proliferation were similar between machined and rough zirconia. The strength of osseointegration for rough zirconia was twice that of machined zirconia at weeks two and four of healing, with evidence of mineralized tissue persisting around rough zirconia implants as visualized by electron microscopy and elemental analysis. CONCLUSION: This unique meso-/micro-/nano-scale rough zirconia showed a remarkable increase in osseointegration compared to machine-smooth zirconia associated with accelerated differentiation of osteoblasts. Cell attachment and proliferation were not compromised on rough zirconia unlike on rough titanium. This is the first report introducing a rough zirconia surface with distinct hierarchical morphology and providing an effective strategy to improve and develop zirconia implants.

Effect of menstrual cycle on frequency of alveolar osteitis in women undergoing surgical removal of mandibular third molar: a single-blind randomized clinical trial.

PURPOSE: To measure the association between the menstrual cycle and the frequency of alveolar osteitis (AO). MATERIALS AND METHODS: In a study with a single-blind design, patients with bilateral impacted third molar teeth underwent randomized surgical extraction: one tooth during the menstrual period and one during the middle of the cycle. The postoperative examiner was unaware of the menstrual cycle status of the patients. The predictor variable was the timing of the menstrual cycle and was grouped as mid-cycle and menstrual period. The outcome variable was AO, which was measured (without knowledge of the menstrual cycle timing) at 2 to 7 days postoperatively. Other study variables included oral contraceptive (OC) use, smoking status, irrigation used during surgery, extraction difficulty, surgeon experience, number of local anesthetic cartridges used, and patient age. Appropriate bi- and multivariate statistics were computed, and the level of statistical significance was set at P < .05. RESULTS: A total of 145 female patients, with a mean age of 24 years, underwent 290 third molar extractions. The overall frequency of AO was 23.45%. The frequency of AO was significantly greater in the middle of the cycle than during the menstrual period inboth the OC users and nonusers (P < .05). Although OC users revealed a significantly greater frequency of AO compared with nonusers (P < .05), no statistically significant differences were found between the 2 groups during the menstrual period (P > .05). CONCLUSIONS: According to the results of the present study, the menstrual cycle could be a determinant risk factor in the frequency of AO. We recommend that elective procedures be performed during the menstrual period in both OC users and nonusers to eliminate the effect of cycle-related hormonal changes on the development of AO.