• Dr. Ashish Kumar Singh
• Dr. Sajal Saini
• Dr. Sridhar Kannan
• Dr. Nitin Arora
• Dr. Abhita Malhotra

Background: When forces are applied on a tooth with periodontal bone loss, stresses with different magnitude and pattern are produced in the periodontium when compared with a tooth with no loss of bone support. The present study was conducted to evaluate and compare the stresses developed on the maxillary anterior tooth region and mini-implant site during intrusion using single and two mini-implants with varying alveolar bone loss levels—a finite element study. Material and methods: CBCT scan of a normal adult human maxilla with normal occlusion is used for collecting data. For the present study, a Finite Element Model (FEM) was generated. This model was a replica of adult human maxilla. The model consisted of periodontal ligament, alveolar bone and all the teeth except third molars. The bracket system simulated will be an MBT bracket system from 3M UNITEK (0.22 slot) and the arch wire was of .019’’x.025’’ stainless steel. A 3- dimensional (3D) quantitative analysis requires a mathematical method, making use of a model accurate both in anatomy and physical characteristics and along with the use of a computer, which has become an indispensable aid as far as 3D analyses are concerned. It was divided into two groups i.e. FE-model Group-Includes single mid mini- implant placed at 12mm from arch wire between the upper central incisors at alveolar bone loss levels at 0mm , 2mm and 4mm. Software used for Finite element model is created using Hypermesh 13.0. FE-model Group-II includes two mini- implant placed at 12mm from the arch wire between the lateral and canine at alveolar bone loss levels at 0mm, 2mm and 4mm. Software used for Finite element model is created using Hypermesh 13.0 Results: The present study has showed that in intrusion orthodontic tooth movement, the stress in anterior teeth increases with increasing bone loss. Highest stresses are observed in central incisor teeth and lowest stresses in lateral incisors. In both, cortical bone and cancellous bone stresses lessen with increasing bone loss. Conclusion: The following conclusions were made from our study: 1).When the mini-implants were placed between the maxillary central incisors, stresses in anterior teeth increased with increase in the alveolar bone loss. proclination due to tipping was observed 2) In both the cortical bone and cancellous bone, the stresses reduced with increase in alveolar bone loss when the mini-implants were placed between the maxillary central incisors.3) At the mini-implant interface when mini-implants placed between the maxillary central incisors maximum stress of around 60Mpa was observed in the cortical bone at mini-implant site.4) When mini-implants placed between maxillary lateral incisor and maxillary canine, stresses in anterior teeth increased with increase in the alveolar bone loss. Proclination due to controlled tipping was observed which was less in magnitude as compared to mini-implants placed between maxillary central incisors 5) In both cortical bone and cancellous bone, the stresses reduced with increase in alveolar bone loss with mini-implants placed between maxillary lateral incisor and canine.6) Stresses of around 7Mpa was observed in the cortical bone at the mini-implant interface with mini-implant placed between maxillary lateral incisor and canine.7) Intrusion was observed more with mini-implant placed between maxillary lateral incisor and canine than when mini-implant placed between maxillary central incisors.8) Mini-implants placed between maxillary lateral incisor and maxillary canine are better in achieving intrusion than mini-implants placed between maxillary central incisors.

Finite element model, two mini- implant, MBT bracket system

"Comparison of Stresses Developed on the Maxillary Anterior Teeth and Mini-implant Site during Intrusion with varying Alveolar Bone Loss Levels using Mini-implants—A Finite Element Study", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 6, page no.80-96, June 2019, Available :http://www.jetir.org/papers/JETIR1906T12.pdf

"Comparison of Stresses Developed on the Maxillary Anterior Teeth and Mini-implant Site during Intrusion with varying Alveolar Bone Loss Levels using Mini-implants—A Finite Element Study", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 6, page no. pp80-96, June 2019, Available at : http://www.jetir.org/papers/JETIR1906T12.pdf