Effects of size and insertion angle of orthodontic mini-implants on skeletal anchorage.

INTRODUCTION: The primary aim of this in vitro study was to compare the insertion torque (IT) and anchorage force (AF) values of 4 different sizes of orthodontic mini-implants with 2 different angles. The second aim was to evaluate the relationship between IT and AF values under different diameter, length, and insertion angle variables. METHODS: A total of 160 mini-implants, including 20 implants in each group, with 4 different sizes (1.6 × 8 mm, 1.6 × 10 mm, 2.0 × 8 mm, and 2.0 × 10 mm) at 2 different angles (70° and 90°), were inserted into bovine iliac bone segments. The IT and AF values leading to 1.5 mm deflection were compared. The correlations between IT and AF values under different variables were also analyzed. RESULTS: The mini-implants with greater diameter and length showed greater IT and AF values (P <0.05). The IT and AF values of mini-implants inserted at 70° angle were significantly greater than those of mini-implants inserted at 90° angle (P <0.001). Significant correlations were found between IT and AF values in all variables. CONCLUSIONS: The diameter, length, and insertion angle of orthodontic mini-implants have significant effects on IT and AF values. Insertion angle and diameter of mini-implants are more effective than implant length on skeletal anchorage. Significant correlations are present between IT and AF values of mini-implants regardless of their diameters, lengths, and insertion angles.

Porcelain refinishing with two different polishing systems after orthodontic debonding.

OBJECTIVE: To compare the effects of two polishing systems on the surface roughness of three types of porcelain after orthodontic debonding. MATERIALS AND METHODS: A total of 90 porcelain discs were fabricated from feldspathic (n = 30), leucite-based (n = 30) or lithia disilicate-based (n = 30) ceramics. Ten samples in each group served as the control and received no surface treatment. The remaining 60 samples in three of the porcelain groups were bonded with lower incisor brackets and debonded using a testing machine in shear mode at a rate of 1 mm/minute crosshead speed. After debonding, the remaining adhesive resin was removed with a tungsten carbide bur. Then, two experimental subgroups (10 each) in each porcelain group were treated as follows: in the first subgroup, porcelain polishing wheel and polishing paste were applied, whereas in the second, polishing was performed using a series of Sof-Lex discs. The average surface roughness (Ra) of the all samples was evaluated using SPM/AFM (surface probe microscope/atomic force microscope). Data were statistically analyzed by analysis of variance for each porcelain material and polishing method. RESULTS: The polishing techniques affected surface roughness significantly. There were significant differences between the groups; higher Ra values were obtained with the use of porcelain polishing wheel and polishing paste (P < .001). CONCLUSION: The application of Sof-Lex discs can produce smoother porcelain surfaces than porcelain polishing wheel and polishing paste.

Possibility of blood and hepatitis B contamination through aerosols generated during debonding procedures.

The primary purpose of this study was to investigate the presence of blood or blood elements in aerosols generated during the debonding procedures. The presence of three hepatitis B carriers in the study group led us to investigate the possibility of hepatitis B virus (HBV) contamination through aerosols, which was the secondary purpose of the study. The study group consisted of 26 patients who had a mean age of 16 +/- 2 years. Collection of aerosol samples was done using a saliva ejector that fit on the handle of the high-speed dental instrument and was attached to a mobile evacuator. A second evacuator was used to remove and collect excess fluid accumulated in the patient's mouth. The guaiac method was used to investigate the presence of occult blood in aerosol and in excess fluid samples. Serum, excess fluid, and aerosol samples of three hepatitis B carriers were tested by enzyme-linked immunosorbent assay for detecting hepatitis B surface antigen (HBsAg) and by polymerase chain reaction for detecting HBV-deoxyribonucleic acid (DNA). Blood was found in all the aerosols and in excess fluid samples. HBsAg was detected in excess fluid samples of the two hepatitis B carriers, whereas HBV-DNA was detected in only one of the excess fluid samples. HBsAg and HBV-DNA were detected in aerosol sample of only one hepatitis B carrier. The results of this study showed that aerosols generated during the debonding procedure should always be considered as potential hazards to health.