Antimicrobial effect of nano-zinc oxide and nano-chitosan particles in dental composite used in orthodontics

Incidence of white spots due to demineralization of enamel and gingival problems is an unacceptable result of orthodontic treatment. Plaque accumulation and bacterial biofilm growth are responsible for these phenomena. The resin-based dental composites used as bonding agents in orthodontics play a major role in mentioned problems. As recent researches assert the antimicrobial effects of chitosan [CS] and zinc oxide [ZnO] nanoparticles [NPs], it seems that adding these nanoparticles to the composite can be beneficial in reducing the number and function of microorganisms. The aim of this study was to evaluate the antimicrobial effects of ZnO-NP and CS-NP-containing orthodontic composite. Antibacterial effectiveness of ZnO-NPs and CS-NPs was assessed in four groups against Streptococcus mutans, Streptococcus sanguis and Lactobacillus acidophilus grown both planktonic and as a biofilm on composites. One group as the unmodified control group and three groups consisting of three different concentrations of ZnO-NPs and CS-NPs mixture: 1%, 5% and 10% [1:1 w/w]. 10[8] CFU/ml microorganism suspensions were provided with spectrophotometer. Biofilm formation was quantified by viable counts. Disc agar diffusion [DAD] test was carried out to determine antimicrobial effects of nanoparticles by measuring the inhibition diameter on brain heart infusion agar plates. Finally,viable counts of microorganisms on days 3, 15 and 30 were collected for the antimicrobial effects of eluted components from composite discs. In biofilm formation test, a reduction in bacterial counts was observed with 10% nanoparticle-containing composites compared with their unmodified counterpart. In the DAD test only 10% nanoparticle-containing specimens showed statistically significant inhibition. The only noticeable datain eluted component test was on day 30 for 10% nanoparticle-containing discs, inhibiting L. acidophilus. It seems that a mixture of ZnO-NPs and CS-NPs has induced an antibacterial activity in resin composite; especially in 10% weight concentrations which was significantly higher than other groups

comparison between craniofacial templates of Iranian and western populations

Templates are very useful tools for diagnosis of malocclusions. A number of templates have been provided for some populations in previous years. Since craniofacial characteristics of different ethnic groups are not the same, each population needs its own norms. The aim of this study was to provide orthodontic craniofacial templates for 8-16 year old Iranian boys and compare dentoskeletal features between Iranian and western populations. 3330 boys with the age range of 8-16 years were examined in Tehran, and 107 cases were finally chosen for the study and their lateral cephalograms were traced. Since there is no universal, consensus about the selection of one specific point or line for cephalometric superimposition, both the sella nasion [SN] and basion nasion [Ba-N] lines were chosen for this purpose. Based on both SN and Ba-N lines, a template was prepared for each age. Simple linear regression analysis was used to evaluate the angles and the multivariant regression analysis for evaluation of landmark vectors. Posterior cranial base, maxillary and mandibular lengths, upper and lower anterior facial heights [N-ANS and ANS-Me] and posterior facial height [S-Go] are greater in Iranian population. But anterior cranial base, height and inclination of the incisors and molar height are similar in two populations

Comparison of the laceback effect at the first phase of fixed orthodontic treatment with MBT technique

This study tried to evaluate the effectiveness of laceback [LB] in the first phase of orthodontic treatment. LB is supposed to prevent anterior tipping of the canines. Designing a randomized control trial. Two groups with LB [group 1] and without laceback [group 2] were used. The first group consisted of 10 girls and 4 boys with the mean age of 14 years 1 month and the second group consisted of 8 girls and 4 boys with the mean age of 15 years 1 month. The impressions were made using prefabricated orthodontic trays. The 0.016 NiTi archwire was the only wire used in the 22-slot brackets. The pre- and post - treatment cephalograms were provided in natural head position. The dental changes in 3 dimensions of space and the vertical skeletal parameters were evaluated using the casts and the cephalograms of the patients. The results showed that the vertical movement of the upper incisors, The angle between upper incisors and SN plan, The forward movement of the molars and the increase in IMPA were greater in group 2 than in group 1. Also, the posterior movement of the canines and the mean change in distances between the contact points of the anterior segments were greater in group 1 than in group 2