No abstract

The aim of this study was to investigate the shear bond strength of bonding to enamel following laser etching with the Er:YAG or Er,Cr:YSGG laser using different irradiation distances. Of 99 extracted human premolar teeth, 90 were divided equally into nine groups. In the control group (group A) the teeth were etched with 38% phosphoric acid. In the laser groups (groups B-I) the enamel surface of the teeth was laser-irradiated, groups B-E with the Er:YAG laser and groups F-I with the Er,Cr:YSGG laser at distances of 1, 2, 4 and 6 mm, respectively. The shear bond strengths were tested using a universal testing machine. The shear bond strengths associated with the Er:YAG laser at 4 and 6 mm and the Er,Cr:YSGG laser at 2, 4 and 6 mm were significantly less than the strengths obtained with the other irradiation distances (p<0.001). The Er:YAG laser at 1 mm and the Er,Cr:YSGG laser at 1 mm etched enamel in the same manner (p>0.05). This finding was confirmed by scanning electron microscopy examination. Irradiation distance did influence the strength of adhesion to enamel. The mean shear bond strengths and enamel surface etching obtained with the Er:YAG laser at 1 and 2 mm and the Er,Cr:YSGG laser at 1 mm were comparable to that obtained with acid etching.

This study evaluated the microleakage of brackets bonded by four different enamel etching techniques. Forty freshly extracted human premolars were divided randomly into four equal groups and received the following treatment: group 1, acid etching; group 2, self-etching primer (SEP); group 3, erbium:yttrium-aluminum-garnet (Er:YAG) laser etching; and group 4, erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser etching. After photopolymerization, the teeth were kept in distilled water for 1 month and then subjected to 500 thermal cycles. Then, the specimens were sealed with nail varnish, stained with 0.5% basic fuchsin for 24 h, sectioned, and examined under a stereomicroscope. In addition, they were scored for marginal microleakage at the adhesive-enamel and bracket-adhesive interfaces from the incisal and gingival margins. Statistical analyses consisted of the Kruskal-Wallis test and the Mann-Whitney U test with Bonferroni correction. Microleakage occurred between the adhesive-enamel and bracket-adhesive interfaces in all groups. For the adhesive-enamel surface, a significant difference was observed between group 1 and groups 2 (P = 0.011), 3 (P = 0.002), and 4 (P = 0.000) on the gingival side. Overall, significant differences were observed between group 1 and groups 3 (P = 0.003) and 4 (P = 0.000). In dental bonding procedures, acid etching was found to result in the least microleakage. Since etching with a laser decreases the risk of caries and is time-saving, it may serve as an alternative to acid etching.

Many orthodontists working on patients with cleft lip and palate (CLP) have shown great enthusiasm for presurgical infant orthopedics (PSIO) to improve surgical outcomes with minimal intervention. Even though every clinician aims to use the best treatment modality for their patients, PSIO effects can be confounded by surgical type and timing of the primary repair, as is discussed in many studies. In such cases, one should be cautious when evaluating the particular outcomes for patients with CLP since it is difficult to differentiate the sole effect of an individual surgical or orthodontic intervention. As with any treatment methodology, nasoalveolar molding (NAM) has both benefits and limitations. Commonly cited concerns with NAM, and PSIO in general, include increased cost, increased burden of care, and a negative impact on maxillary growth. However, NAM cannot be deemed as having apparent long-term negative or positive effects on skeletal or soft tissue facial growth, based on previous studies. A review of the literature suggests that NAM does not alter skeletal facial growth when compared with the samples that did not receive PSIO. Nevertheless, the published studies on NAM show evidence of benefits to the patient, caregivers, the surgeon, and society. These benefits include documented reduction in severity of the cleft deformity prior to surgery and as a consequence improved surgical outcomes, reduced burden of care on the care givers, reduction in the need for revision surgery, and consequent reduced overall cost of care to the patient and society.

The purpose of this study was to evaluate whether 50 Hz extremely low frequency electromagnetic fields (ELF-EMFs) affect the amount of orthodontic tooth movement in rats. The experiments were performed on 18 male Sprague-Dawley rats. The rats were randomly divided into three groups (n = 6): cage-control (Cg-Cnt) group (n = 6); sinusoidal electromagnetic field (SEMF) group (n = 6); and pulsed electromagnetic field (PEMF) group (n = 6). In SEMF and PEMF groups, rats were subjected to 1.5 mT EMF exposure eight hours per day for eight days. In order to obtain tooth movement, holes were drilled on the right and left maxillary central incisors of the rats at a distance 1.5–2 mm away from the gingiva and 20 g of orthodontic forces were applied to the teeth. Generated linear model for repeated measures and Bonferroni tests were used to evaluate the differences between the groups. Interactions among groups by days were found by using Pillai's trace multivariate test. The results showed that significant differences were present among the groups (F = 5.035; p = 0.03) according to the extent of tooth movement. Significant differences between the amount of tooth movements were determined especially after the fifth day and the following days six, seven and eight (p < 0.001). Within the limitations, according to the results of the present study, the application of ELF-EMF accelerated the orthodontic tooth movement in rats.