Evaluation of stress distribution values at the temporomandibular joint and distalization of teeth during en-masse retraction of the mandibular dentition using buccal shelf bone screws: A FEM study.

INTRODUCTION: Present Finite-element-method (FEM) study evaluates the stress distribution values at the Temporomandibular-Joint (TMJ) during en-masse retraction of the mandibular dentition using buccal shelf bone screws with varying magnitudes of forces. MATERIAL AND METHODS: Nine replicas of a pre-existing three-dimensional finite element model of the craniofacial skeleton and articular disc from Cone-Beam-Computed-Tomography (CBCT) data and Magnetic-Resonance-Imaging (MRI) data of a patient were used. Buccal shelf (BS) bone screws were inserted buccal to the mandibular second molar region. Forces of magnitudes 250 gm, 350 gm and 450 gm were applied through NiTi coil springs along with stainless-steel archwires of sizes 0.016 × 0.022-inch, 0.017 × 0.025-inch and 0.019 × 0.025-inch. RESULTS: On the articular disc, the maximum stress was observed at the inferior region and the inferior part of the anterior and posterior zone at all force levels. The stress on the articular disc and displacement of teeth increased with increase in force levels in all the 3 archwires. The maximum stress at the articular disc and displacement of teeth was observed for 450 gm force and the least for 250 gm force. No significant difference in the amount of displacement of teeth or the stresses produced at the articular disc was seen with increasing the size of the archwire. CONCLUSION: With the present FEM study, we can deduce that it is better to use forces of lower levels on patients with temporomandibular-disorders (TMD) so as to reduce the stresses produced at the TMJ to avoid worsening of the TMD condition.

Efficacy of 1% acetic acid in the treatment of chronic wounds infected with Pseudomonas aeruginosa: prospective randomised controlled clinical trial.

Chronic wounds are those wounds that are persistent and do not respond to any sort of treatment. The concept of using topical antiseptics on open wounds is to prevent and treat infections. They also help to shorten the time taken to heal the wounds. The use of topical agents on wounds to prevent infection is a minimal ability to develop resistance to the microorganisms. Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen with innate resistance to many antibiotics. In places that are economically backward, these problems get compounded by the inability of patients to afford newer expensive drugs. Topically applied dilute acetic acid, which is cheap and easily available, has been found to be effective in such chronic wounds. In the present study, an attempt has been made to use 1% acetic acid as the sole antimicrobial agent for the treatment of pseudomonal wound infections. A control limb was used in which the wounds were treated with normal saline. Our objective was to evaluate the efficacy of acetic acid in low concentration of 1% in chronic wounds infected with P. aeruginosa. This was a prospective study conducted over a period of 6 months. INCLUSION CRITERIA: All patients with chronic wounds infected with P. aeruginosa. EXCLUSION CRITERIA: Wounds due to massive burns, suspected malignancy, immunocompromised individuals and individuals with sepsis. A total of 32 patients enrolled in the study. Subjects were randomised equally to the 1% acetic acid group and saline dressing group. None of the patients received any systemic antibiotics during the study period and received twice daily dressings. The endpoint of the treatment was wounds free of P. aeruginosa. The duration of treatment required to eliminate the Pseudomonas from the wounds in the acetic acid group was on an average 7 days less than that required by the saline group. P value was <0·001. In the 1% acetic acid group irrespective of the sensitivity of the organism to antibiotics, Pseudomonas organisms were eliminated within the same time period - 4·5 days. In the saline group, susceptible organisms were eliminated within 11·5 days and multidrug-resistant organisms were eliminated by 15·5 days. 1% acetic acid is a simple, safe and effective topical antiseptic that can be used in the elimination of P. aeruginosa from chronic infected wounds.