Frequency of Bonded Bracket Failure in Patients, Undergoing Fixed Orthodontic Treatment

OBJECTIVE: The objective of our study is to determine frequency of bracket bond failure in relation to age, gender, most commonly involved tooth and quadrant. METHODOLOGY: In this descriptive cross-sectional study, a total of 100 patients with ages ranging from 10 to 30 years needing corrective orthodontic treatment were selected for the study. This survey was conducted at Altamash Institute of Dental Medicine, Karachi. The survey was initiated on 30th November 2019 and was concluded on 30th May 2020. A questionnaire was used to evaluate the frequency of bonded bracket failure in patients undergoing orthodontic treatment. The bonded metallic brackets were light cured for 40 seconds, and initial alignment arch wires were inserted. Bonded bracket failure was recorded over a period of six months. RESULTS: The initial debonding results of the present study demonstrated a high number of debonded brackets in mandibular dentition as compared to the maxillary dentition. Whereas, when the teeth were debonded for the second time, a greater number of maxillary teeth were found to be affected by the debonding of the brackets. Both genders demonstrated a greater rate of bracket debonding in the second premolar area and lowest in the molar area. In our study, age and gender had no significant relationship with bracket bond failure and teeth involved in debonding. CONCLUSIONS: The frequency of bonded bracket detachment during orthodontic treatment is very common. Our study concluded that females were more affected by the bracket bond failure as compared to the males along with the second premolar being the most commonly associated tooth during an active orthodontic treatment. KEYWORDS: Bonded brackets, Bracket failure, Frequency, Orthodontic treatment, Orthodontics

Registration-free workflow for electromagnetic and optical navigation in orbital and craniofacial surgery

The accuracy of intra-operative navigation is largely dependent on the intra-operative registration procedure. Next to accuracy, important factors to consider for the registration procedure are invasiveness, time consumption, logistical demands, user-dependency, compatibility and radiation exposure. In this study, a workflow is presented that eliminates the need for a registration procedure altogether: registration-free navigation. In the workflow, the maxillary dental model is fused to the pre-operative imaging data using commercially available virtual planning software. A virtual Dynamic Reference Frame on a splint is designed on the patient’s fused maxillary dentition: during surgery, the splint containing the reference frame is positioned on the patient’s dentition. This alleviates the need for any registration procedure, since the position of the reference frame is known from the design. The accuracy of the workflow was evaluated in a cadaver set-up, and compared to bone-anchored fiducial, virtual splint and surface-based registration. The results showed that accuracy of the workflow was greatly dependent on tracking technique used: the workflow was the most accurate with electromagnetic tracking, but the least accurate with optical tracking. Although this method offers a time-efficient, non-invasive, radiation-free automatic alternative for registration, clinical implementation is hampered by the unexplained differences in accuracy between tracking techniques.

Effectiveness of an anterior mini-screw in achieving incisor intrusion and palatal root torque for anterior retraction with clear aligners:

ABSTRACT Objectives To analyze the biomechanical system of anterior retraction with clear aligner therapy (CAT) with and without an anterior mini-screw and elastics. Materials and Methods Models including a maxillary dentition (without first premolars), maxilla, periodontal ligaments (PDLs), attachments, and aligners were constructed and imported to finite element software. Three model groups were created: (1) control (CAT alone), (2) labial elastics (CAT with elastics between the anterior mini-screw and buttons on central incisors), and (3) linguoincisal elastics (CAT with elastics between the anterior mini-screw and precision cuts on the lingual sides of the aligner). Elastic forces (0–300 g, in 50 g increments) were applied. Results CAT alone caused lingual tipping and extrusion of the incisors. Labial elastics caused palatal root torquing and intrusion and mesial tipping of the central incisors, while linguoincisal elastics produced palatal root torquing and intrusion of both central and lateral incisors. Second premolars were intruded in all three groups, with less intrusion in the linguoincisal elastics group. For the control group, stress was concentrated on both labial and lingual root surfaces, alveolar ridge, and cervical and apical PDLs. Stress was more concentrated in the labial elastics group and less concentrated in the linguoincisal elastics group. Conclusions CAT produced lingual tipping and extrusion of incisors during anterior retraction. Anterior mini-screws and elastics can achieve incisor intrusion and palatal root torquing. Linguoincisal elastics are superior to labial elastics with a lower likelihood of buccal open bite. Root resorption and alveolar defects may occur in CAT, more likely for labial elastics and less likely for linguoincisal elastics.

Biomechanical Effects of Torquing on Upper Central Incisor with Thermoplastic Aligner: A Comparative Three-Dimensional Finite Element Study with and Without Auxillaries

Background and Objectives: This study was conducted to determine the effective method to torque the incisor with thermoplastic aligner using a three-dimensional (3D) finite element method. Materials and Methods: Three finite element models of maxilla and maxillary dentition were developed. In the first model, thermoplastic aligner without any auxiliaries was used. In the second and third models, thermoplastic aligner with horizontal ellipsoid composite attachment and power ridge were used, respectively. The software used for the study was ANSYS 14.5 FE. A force of 100 g was applied to torque the upper right central incisor. The resultant force transfer, stress distribution, and tooth displacement were evaluated. Results: The overall tooth displacement and stress distribution appeared high in the model with power ridge, whereas the root movement was more in the horizontal ellipsoid composite attachment model. The model without any auxillaries produced least root movement and stress distribution. Conclusion: Horizontal ellipsoid composite attachment achieved better torque of central incisor than the model with power ridge and model without any auxillaries.