Evaluation of the bisphenol released in the saliva after residual adhesive removal in orthodontic patients by using ultrasonic scaling and rotary system: A single-center randomized clinical trial.

INTRODUCTION: Bisphenol A (BPA) is a substance commonly used in dental materials with noxious properties. Monomers of this substance may be dissolved in the saliva and cause adverse effects. This study aimed to evaluate the amount of BPA released in the saliva after residual adhesive removal in orthodontic patients using an ultrasonic scaler (US) and tungsten carbide bur (TCB). METHODS: This single-center randomized clinical trial was conducted on 40 subjects whose stainless-steel brackets were bonded directly with light-cured bonding and composite. The subjects were randomly divided into 2 equal groups (n = 20) of TCB or US according to the adhesive removal method. The salivary BPA level was determined using high-performance liquid chromatography-mass spectrometry. And adhesive cleaning time was measured by a stopwatch. Data were analyzed by SPSS using an independent t test and paired-samples t test (P <0.05). RESULTS: The mean salivary BPA level was significantly lower in the TCB method than in the US method. (1.008 ± 0.061 µg/mL and 2.83 ± 0.24 µg/mL, respectively) (P <0.001). The mean adhesive cleanup time was significantly shorter in the TCB method than in the US method (8.86 ± 0.83 minutes and 13.20±1.02 minutes, respectively) (P <0.001). CONCLUSIONS: According to the results, residual adhesive removal with TCB released less BPA in saliva and shortened the adhesive cleaning time than the US method. TRIAL REGISTRATION: The trial was registered at the Iranian Registry of Clinical Trials (IRCT20200702047988N1). PROTOCOL: The protocol was not published before trial commencement.

Comparison of shear bond strength of rebonded brackets prepared with different methods of resin removal: an in vitro study.

AIM: Clinicians and researchers have always made every effort to achieve proper bonding between the surface of the tooth and the rebonded orthodontic brackets in order to prevent the re-fracture failure of orthodontic pressures throughout treatment. The aim of this study was to determine the bond strength of rebonded brackets by four adhesive removal methods.

(6,6'-Dimethyl-2,2'-bipyridine-κN,N')diiodidomercury(II).

In the title complex, [HgI(2)(C(12)H(12)N(2))], the Hg(II) atom has a distorted tetra-hedral coordination formed by two N atoms of the 6,6'-dimethyl-2,2'-bipyridine ligand and two terminal I atoms [N-Hg-N = 70.1 (2) and I-Hg-I = 130.59 (3)°]. The crystal packing features π-π contacts between the pyridine rings of adjacent mol-ecules [centroid-centroid distance = 3.773 (5) Å] and also between a pyridine ring of one mol-ecule and the five-membered chelate ring of an adjacent mol-ecule [centroid-centroid distance = 3.668 (4) Å].