The effect of cigarette smoke on the shear bond strength of metallic and ceramic orthodontic brackets: An in vitro study

Metallic vs Ceramic Bracket Failures After 12 Months of Treatment: A Prospective Clinical Trial

INTRODUCTION

Orthodontic treatment with fixed vestibular appliances is still widely used worldwide. When choosing the aesthetic alternative of ceramic brackets, the possibility of failure and cracking of braces should be considered. Therefore, the aim of the present study was to compare the failure rates of ceramic and metal brackets in a 12-month clinical study.

METHODS

Eighty patients undergoing fixed orthodontic treatment with vestibular appliances were enrolled and divided into 2 equal groups: MET for metal brackets and CER for ceramic brackets. After bonding, bracket failures were recorded for 12 months, along with the archwire placed at the time of failure. Angle's dental class, skeletal class, Wits appraisal, Little's irregularity index, overjet, overbite, age, and gender of the patients were recorded from pretreatment cephalometric tracings and study casts. The data were statistically analysed (P < .05).

RESULTS

Significantly higher failure rates were found for ceramic brackets in the overall analysis, in the mandibular arch, and in the posterior region. Regression analysis revealed a significant influence of round nickel-titanium archwires on higher failure rates, whilst a significant influence of rectangular archwires was found on lower failure rates.

CONCLUSIONS

Ceramic brackets showed higher failure rates. Patients should be aware that orthodontic treatment with ceramic brackets may involve delays and inconvenience due to the higher failure rate compared to metal brackets.

Effect of cigarettes smoke on bonded polymeric restorations: OCT study

Background

Up to date, the effect of cigarette smoke (CS) on the adhesive properties of the restorative materials bonded to tooth structure is still unclear. It is still questionable if it interferes with the durability and clinical success of these restorations. Few numbers of studies reported the assessment of microgaps of dental composite using cross-polarization optical coherence tomography (CP-OCT). The aim of this study was to evaluate the presence of interfacial microgaps between composite resin restoration and the tooth structure with or without exposure to CS under the CP-OCT.

Materials and methods

In this in-vitro study, a standardized round class-V cavities were prepared in twenty extracted, caries-free human molar teeth, and they were divided randomly into two groups (n = 10). Adhesive system (Gluma universal, Kulzer GmbH) was applied followed by filing the prepared cavities with flowable composite restoration (Charisma, Kulzer GmbH). Then, exposure to CS (40 cigarettes/day) was carried out for 14 days and the samples were stored in normal saline solution after each smoke exposure cycle. Next, all samples were immersed in ammoniac silver nitrate for 24 h, followed by immersion in a photo-developing solution for 8 h. Optical comparison was carried out by CP-OCT to assess microgaps percentage between smoke (SG) and non-smoke groups (NSG) at the axial walls (AW) and cavity floor (CF).

Results

Independent T-test showed that there was a significant difference between the two groups (SG, NSG) in AW microgaps percentage (p = 0.008), while there was no difference in CF (p = 0.15).

Conclusion

It can be inferred from the current finding that OCT can be used to predict the adaptability of the bonded restoration under the thermochemical influence. CS has a negative effect on the marginal integrity of the bonded polymeric restorations.

Effect of cigarette smoking on alveolar bone thickness and density in patients undergoing leveling and alignment of crowded lower anterior teeth: a controlled clinical trial

OBJECTIVE

To evaluate the effect of cigarette smoking on the alveolar bone thickness and density in patients undergoing leveling and alignment of crowded lower anterior teeth.

METHODS

This controlled clinical trial involved 17 smokers and 17 nonsmokers with mild to moderate crowding of the anterior mandibular teeth. Two cone-beam computed tomography images of the mandible were taken before and after treatment. The length of each tooth root was calculated in each T0 image, and the root was divided into three equal regions. Three lines were drawn parallel to the line of the cementoenamel junction at these three regions of the root, and the previously drawn lines were used to measure bone thickness and bone density.

RESULTS

The mean changes in cortical bone thickness and bone density were significantly smaller in smokers than nonsmokers. Cortical bone thickness and bone density were significantly lower after than before treatment in both smokers and nonsmokers.

CONCLUSION

In addition to all of its known dangers, cigarette smoking may also harm the alveolar bone by decreasing the bone thickness and density during orthodontic treatment in heavy smokers.

Does a diluted chlorhexidine-based orthodontic mouthwash cause less discoloration compared to chlorhexidine mouthwash in fixed orthodontic patients? A randomized controlled trial

OBJECTIVE

Chlorhexidine gluconate is currently the most effective oral antimicrobial agent against microorganisms, but discoloration of the teeth prevents its long-term use and can reduce patient cooperation. In this study, the effect of chlorhexidine and a diluted chlorhexidine-based, fluoride, cetylpyridinium and vitamin added mouth rinse (Orthokin) on stain index in fixed orthodontic patients was compared.

MATERIALS AND METHODS

This study was performed as a double blind randomized controlled trial on 50 patients undergoing fixed orthodontic treatment in the age group of 14-30 years. The patients were categorized as two groups of chlorhexidine and Orthokin mouth rinses and were asked to use mouthwash for eight weeks. Groups were matched according to colouring food consumption. Extrinsic staining index was assessed by modified Loben technique. Data was analysed by SPSS software. P value was set to be 0.05.

RESULTS

In the chlorhexidine group, the stain extent index and overall stain index were increased significantly at 8 weeks (P<0.001 and P=0.002, respectively). However, the increase in stain intensity index was insignificant (P=0.07). In Orthokin group, the changes in stain extent, stain intensity and overall stain were insignificant (P=0.66, P=1.000, P=0.47, respectively).

CONCLUSION

According to the results of the present study, chlorhexidine mouthwash causes more staining of teeth compared to Orthokin mouthwash. It seems that lower concentrations of chlorhexidine can be prescribed to orthodontic patients. Although these compounds are effective in sense of oral hygiene, they do not cause significant discoloration.

Effect of nicotine exposure on the rate of orthodontic tooth movement: A meta-analysis based on animal studies

Background

Nicotine exposure has been reported to modify bone cell function and the osseous metabolism with potential effects on the rate of orthodontic tooth movement.

Objectives

To systematically investigate and quantitively synthesize the most recent available evidence from animal studies regarding the effect of nicotine exposure on the rate of orthodontic tooth movement.

Search methods

Unrestricted searches in 7 databases and hand searching were performed until July 2020 (PubMed, Central, Cochrane Database of Systematic Reviews, SCOPUS, Web of Science, Arab World Research Source, ProQuest Dissertations and Theses Global).

Selection criteria

We searched for controlled studies on healthy animals investigating the effect of nicotine on the rate of orthodontic tooth movement.

Data collection and analysis

Following study retrieval and selection, relevant data was extracted and the risk of bias was assessed using the SYRCLE’s Risk of Bias Tool. Exploratory synthesis and meta-regression were carried out using the random effects model.

Results

From the initially identified records, 5 articles meeting the inclusion criteria were selected and no specific concerns regarding bias were identified. Quantitative data synthesis showed that the rate of orthodontic tooth movement in the nicotine exposed rats was higher than in the control group animals (2 weeks of force application; 0.317 mm more movement in nicotine exposed rats; 95% Confidence Interval: 0.179–0.454; p = 0.000). No effect of the concentration or the duration force application was demonstrated following exploratory meta-regression.

Conclusion

Rats administered with nicotine showed accelerated rates of orthodontic tooth movement. Although, information from animal studies cannot be fully translated to human clinical scenarios, safe practice would suggest that the orthodontist should be able to identify patients exposed to nicotine and consider the possible implications for everyday clinical practice.