In vitro evaluation of microbial contamination and the disinfecting efficacy of chlorhexidine on orthodontic brackets

BACKGROUND

Contamination of orthodontic appliances is due to the unhygienic practices followed during manufacturing and packaging processes, which may lead to cross-contamination. Although literature has indicated the need for sterilization or disinfection of orthodontic appliances before using in the oral cavity, this is still not employed in routine clinical practice. In this view, the current study evaluates the bacterial load on orthodontic brackets along with the disinfecting efficacy of chlorhexidine.

METHODS

A total of 140 brackets were obtained from four different manufacturers and divided into six groups: group 1 (American Orthodontics; n = 30), group 2 (3M Unitek; n = 30), group 3 (Ortho Organizers; n = 30), group 4 (China Dental Orthodontic; n = 30), group 5 (negative control; n = 10), and group 6 (positive control; n = 10). Various microbiological and biochemical tests were conducted on the brackets to detect the type and growth of bacteria. Brackets that showed microbial contamination were then subjected to disinfection using 0.01% and 2% chlorhexidine solutions.

RESULTS

Microbial contamination was detected on brackets of all the four groups. Bacteria, including Staphylococcus aureus, S. epidermidis, Lactobacilli, Klebsiella pneumoniae, Bacillus licheniformis, and B. cereus, were identified in these groups. Upon disinfection with 0.01% chlorhexidine solution, brackets in group 2 displayed complete decontamination, while all brackets in the other groups containing gram-negative bacteria exhibited complete decontamination with 2% chlorhexidine.

CONCLUSION

Orthodontic brackets received from four manufacturers showed high bacterial contamination. Disinfecting ability of 2% chlorhexidine proved highly effective in destroying both gram-positive and gram-negative bacteria. Therefore, use of 2% chlorhexidine in clinical practice for the disinfection of orthodontic brackets is suggested, before placement in the oral cavity.

Esthetic Outcome and Airway Evaluation following Bi-Jaw Surgery V/S Mandibular Setback Surgery in Skeletal Class III Malocclusion Using Surgery First Approach

Background:

Class III skeletal deformity is the result of mandibular prognathism, maxillary deficiency, or a combination. Treatment frequently requires a combination of orthodontics and orthognathic surgical procedures to improve facial esthetics and harmonize facial profile.

Objectives:

The objective of the study is to assess and quantify, by means of cephalometric analysis, the pre- and postoperative soft-tissue and airway changes following bi-jaw surgery and mandibular setback surgery after the correction of skeletal Class III deformities using surgery-first approach.

Materials and Methods:

Patients with skeletal Class III malocclusion were classified based on the A point–nasion–B point, beta angle, and Witt's appraisal. The cases were divided based on the type of surgery-first orthognathic approach they received. Group A (20 patients) comprised patients who underwent bi-jaw surgery (Le Fort I + bilateral sagittal split osteotomy [BSSO]) and Group B (20 patients) who underwent BSSO alone. After the lateral cephalograms were digitized, the cephalograms were evaluated for soft-tissue changes and airway changes.

Results:

The soft-tissue response to simultaneous two-jaw surgery was superior to those seen in mandibular setback procedures with the exception of the changes seen in the facial contour angle and soft-tissue facial angle. There was a significant decrease in lower airway in cases treated with mandibular setback alone.

Conclusion:

Cases treated with bi-jaw surgeries had a significant soft-tissue improvement in the long term compared to mandibular setback surgeries. Since there was a significant reduction in the lower airway in cases treated with isolated mandibular surgeries, bi-jaw surgeries maybe preferred over mandibular setback surgeries.

Association of Transforming Growth Factor Alpha and Methylenetetrahydrofolate reductase gene variants with nonsyndromic cleft lip and palate in the Indian population

Objectives:

The aim was to evaluate the relationship of the K-primer variant of the transforming growth factor-alpha (TGF-α) gene and C677T variant of the methylenetetrahydrofolate reductase (MTHFR) gene with nonsyndromic cleft lip and palate (CL/P) in the Indian population.

Setting and Sample Population:

The study group consisted of DNA samples of 25 subjects with nonsyndromic CL with or without cleft palate and 25 unrelated controls, already existing in the Department of Orthodontics, D.A.P.M.R.V. Dental College, Bengaluru, Karnataka, India.

Materials and Methods:

The DNA samples were divided into two categories: Group A which included the 25 subjects with nonsyndromic CL/P; and Group B, which consisted of the 25 unrelated controls. The polymerase chain reaction (PCR) test was done for amplification of the region of interest from the DNA samples. Restriction digestion was then performed on the amplified product using the restriction enzyme HinfI, separately for each of the variants. The digested PCR products were separated into channels on a 1.5% agarose gel containing ethidium bromide in an electrophoretic chamber. A U.V. transilluminator was used to see the specific bands of base pairs of the digested PCR products.

Results:

In Group A, the TGF-α gene variant was present in 16 subjects (P = 0.001) and MTHFR gene variant was present in 8 subjects (P = 0.185). A combination of both gene variants were present in seven subjects, which was an interesting finding. In Group B, four subjects tested positive for the TGF-α and MTHFR gene variants.

Conclusions:

The TGF-α gene variant and a combination of TGF-α + MTHFR gene variants significantly contribute to the development of nonsyndromic CL/P and can be considered as genetic markers for Indian population. The MTHFR gene variant, though a minor risk factor, cannot be considered as a genetic marker.

Applicability of two methods of mixed dentition analysis in a contemporary Indian population sample

AIM

More than 10 years experience in implementing the Tanaka Johnston and Moyers methods has shown that they overestimate the sizes of unerupted canines and premolars when used in populations other than the Caucasian. This study was designed to assess the applicability of the two most commonly used methods of mixed dentition analysis and to attempt to derive a more accurate and precise formula to predict the sizes of the unerupted premolars and canines in a sample of Indian population.

MATERIALS AND METHODS

The sample included 200 study models (100 male, 100 female). Tanaka Johnston's and Moyer's equations were applied to this sample and the mean differences between the actual and estimated tooth widths were determined. New regression equations were derived using lower first molars and incisors as the predictors.

RESULTS

The mean difference between the actual and estimated values of canines and premolars using Tanaka Johnston's and Moyers methods were clinically and statistically significant. Therefore new regression equations were derived taking lower first molars and incisors as the predictors for both sexes. On validation, these equations were found to be accurate and precise for this population.

CONCLUSION

It is recommended to use these equations as a method of mixed dentition analysis for the Indian population.

An evaluation of nasolabial angle and the relative inclinations of the nose and upper lip

Esthetics is one of the major motivating factors for patients seeking orthodontic treatment. Hard tissue and soft tissue drape both determine the facial esthetics. The structures in this region are so variable that the nasolabial angle (NLA) has been drawn differently by various investigators. Variations can lead to erroneous conclusions in orthodontic diagnosis.

AIMS AND OBJECTIVES

The study was done to evaluate a reliable method of constructing the nasolabial angle (NLA) and to correlate the soft tissue profile parameters with one another.

MATERIALS AND METHODS

Lateral cephalogram of 50 randomly selected adult patients were taken. The tracings were made and 10 copies of each tracing were randomly distributed to 10 different orthodontists to draw the NLA.

RESULTS

Pearson's correlation coefficient (r) showed both N/ FH and L/FH angles to have significant p values when compared with NLA. The regression analysis showed that the nasolabial angle can be calculated for any given value of N/FH or L/FH by the formula: NLA = 80.33° + 1.02° (N/FH) and NLA = 14.2° + 1.04° (L/FH). The mean value of N/FH was 17.42° ± 8.40° and L/FH was 80.68° + 6.45° for this sample. Inter examiner reliability calculated by repeated measures of ANOVA and Dahlerg's formula showed high degree of reliability and reproducibility of the method.

CLINICAL SIGNIFICANCE

NLA can be predicted for any given value of N/FH and L/FH. NLA = 80.33° + 1.02° (N/FH) and NLA = 14.2° + 1.04° (L/FH). If an individual has either N/FH or L/FH in the normal range but not the NLA then one could calculate the correct NLA using this formula. Thereby the NLA can be brought within the normal range by altering the other nasolabial parameters by correct treatment planning. Since the nasolabial angle plays a vital role in profile esthetics of a person, the clinician should place greater emphasis in evaluating this area and plan treatment mechanics to place this angle within the accepted normal variation.