Change in the Spatial Position of Mini-implants During Distal Movement of the Entire Maxillary Dentition: An Observational CBCT Study.

OBJECTIVE: To determine the change in the sagittal and vertical position of the mini-implant placed in the maxilla during distal movement of the entire maxillary dentition. MATERIALS AND METHODS: Twenty eight mini-implants, fourteen on each side were evaluated in young healthy patients in the age group of 15 years to 25 years. Distal movement of the entire maxillary arch was performed with 1.2 mm x 8 mm stainless steel mini-implants on 0.018" x 0.025" stainless steel wire. CBCT were taken at the start of (T1) and at the end of six months (T2) of distal movement of the maxillary teeth. The vertical and sagittal angulation of the mini-implant was measured at T1 and T2. The linear distance between the mini-implant and the alveolar crest, the maxillary sinus, the maxillary second premolar and the maxillary first permanent molar were measured. The change in angulation and the linear displacement of the mini-implant were evaluated in the vertical and sagittal plane. Wilcoxon signed rank test was performed to determine if there was a statistically significant change in the position of the mini-implant. RESULTS: Vertically, there was a significant change in the linear distance between the miniimplant and the alveolar crest on the right side (p≤.006) and the mini-implant and the maxillary sinus on the left side (p≤.003). Sagittally, there was a statistically significant rotation of the miniimplant occlusally (left side p≤.004 and right side p≤.002). The head and tip of the mini-implant were displaced towards the maxillary second premolar and away from the maxillary first permanent molar respectively. There was a significant relative displacement of the mini-implant anteriorly away from the maxillary first permanent molar (left side p≤.026 and right side p≤.041)and closer to the maxillary second premolar (left side: p≤..011 and right side: p≤.002). CONCLUSIONS: There was a statistically and clinically significant rotation of the mini-implant in the vertical and sagittal direction during distal movement of the entire maxillary teeth. The linear displacement of the mini-implant was more pronounced in the sagittal direction compared to the vertical direction.

Role of the Growth Hormone Receptor (GHR) Gene in Skeletal Class II Malocclusion and Its Significant Influence on the Skeletal Facial Profile in Both the Sagittal and Vertical Dimensions: A Systematic Review.

This systematic review aims to determine the role of the growth hormone receptor (GHR) gene in skeletal malocclusion and its significant influence on the growth of the maxilla and the mandible in both sagittal and vertical dimensions. A search of the electronic databases of PubMed, Google Scholar, and Cochrane up to and including the year 2023 was made. In addition to this, a hand search of orthodontic and dentofacial orthopaedic journals was carried out. This search included randomized control trials. The Mesh terms used were "skeletal class II malocclusion", "mandibular retrognathism", "sagittal malocclusion", "genetic expression", "genetic factors", "genetic study", "genetic polymorphism", and "single nucleotide polymorphism". The inclusion criteria included studies such as clinical trials and orthopaedic appliances in the presurgical phase. The exclusion criteria for the study were studies not in the English language, case reports, case series, and studies with irrelevant data. It has been cited in various literature that polymorphic variations of the GHR gene could cause variations in mandibular morphogenesis affecting both the mandibular body length and ramal height. However, its effects are quite variable and are based on different population groups. Polymorphism of the GHR gene can be considered a reliable indicator predicting variations in affecting the growth of the mandible with greater significance in affecting the vertical ramal height compared to the body length of the mandible. Its effects on the maxillary skeletal base are rather limited comparatively.

Influence of the maxillary third molars and the surrounding cortical plate during maxillary tooth movement with TADS- A CBCT Study.

OBJECTIVE: To determine the influence of the presence/absence of third molars and intact/loss of cortical plate of the maxillary tuberosity on the amount of distal movement of the maxillary first permanent molar during distal movement of the maxillary dentition with mini-implants. MATERIALS AND METHODS: Thirty six maxillary tuberosity sites were evaluated in eighteen young adult patients. The distal movement of the entire maxillary dentition was performed with mini-implants with 200 g of distalising force applied from the mini-implant placed in the maxillary posterior buccal region to attachments placed on the arch wire between the maxillary lateral incisor and canine bilaterally. The distal movement of the maxillary first permanent molars was measured on lateral cephalograms. The maxillary tuberosity sites with intact cortical plate due to congenitally missing third molars or atraumatic extraction of third molars (G1), partial loss of cortical plate due to surgical removal of third molars (G2), fully erupted third molars (G4), third molars located at (G3), and below the cementoenamel junction (G5) were evaluated with cone beam computed tomography. One way Anova and Fisher LSD test was done. RESULTS: The order of greater to lesser amount of distal movement of the maxillary first permanent molar depending on the integrity of maxillary of tuberosity was partial loss of cortical plate, third molars at the cementoenamel junction, third molars below the cementoenamel junction, intact cortical plate and fully erupted third molars. CONCLUSION: The integrity of the cortical plate and the relative position of the maxillary third molar to the second molar influence the amount of distal movement of the maxillary first permanent molar during distal movement of the maxillary teeth with TADS. CLINICAL RELEVANCE: The amount of distal movement of the maxillary dentition appears to depend on the presence or absence of the third molars and the condition of the cortical plate in the region of the maxillary tuberosity and thereby greatly influence the outcome of treatment.

Patients' perception of orthodontic mini implants at different sites: anterior vs posterior maxilla.

The aim of this study was to compare patients' overall perception of treatment with orthodontic mini implants placed in the maxillary anterior or posterior region. Twenty young adult patients were divided into 2 groups (n = 10). In group 1 (G1), mini implants were placed in the maxillary anterior midline just below the labial frenum. In group 2 (G2), mini implants were placed bilaterally in the maxillary posterior region, between the maxillary second premolar and first molar at the mucogingival junction. Questionnaires were used to record patient experiences with the mini implants at 3 time points: immediately after placement, 1 week after placement, and immediately after removal. Patients were offered 3 choices representing different levels of intensity. The patients were also asked to record their responses on a scale of 0 to 10 for each parameter evaluated. Each unit was subdivided into units of 10. A score of 0 indicated the best response and 10 indicated the worst response. Statistical analyses included the Student t and chi-square tests. Patients in G2 reported greater discomfort during mini implant placement than did patients in G1 (P = 0.036). During the following week, some patients experienced a bad taste at the site, rated significantly worse in G2 than in G1 (P = 0.043). There was also a statistically significant difference between the 2 groups (P = 0.032) in response to a question about the overall experience of the procedure, with G2 rating it better than G1; in the anterior region, the patients had a mean score of 2.00 (SD, 1.29; 95% CI, 0.22 to 3.78); and in the posterior region, they had a mean score of 0.00 (SD, 0.00; 95% CI, 0.81 to 3.19). There were no statistically significant differences in the distributions of responses for any measured outcome between G1 and G2. At mini implant removal, a greater number of patients in G2 than in G1 found the entire procedure to be somewhat different (unfamiliar) compared with other routine orthodontic procedures (P = 0.004). Despite the scores for the question on overall experience, the responses to questions about individual aspects of treatment indicated that patients with mini implants placed in the anterior region had a better experience than did patients with mini implants placed in the posterior region.

Minimum volume of infiltrative anesthetic required for pain-free placement of mini-implants: a split-mouth clinical trial.

OBJECTIVE: To determine the minimum volume of infiltrative anesthetic required for pain-free mini-implant placement in the maxillary buccal region by comparing the efficacy of 1.0 mL with 0.5 mL of 2% lignocaine with 1:200,000 epinephrine during mini-implant placement. METHOD AND MATERIALS: This split-mouth study involved 19 healthy patients without systemic disease, recent history of allergy, or medications within the age group of 17 to 28 years belonging to both sexes requiring bilateral buccal mini-implants in the posterior maxilla. Lignocaine 2% with 1:200,000 epinephrine (0.5 mL and 1.0 mL) was randomly injected between the right and left side 30 minutes apart for each consecutive patient. Mini-implants were placed 5 minutes after the administration of the infiltrative anesthetic. The pain response was evaluated during mini-implant placement (T1), and 5 minutes (T2) and 10 minutes (T3) after mini-implant placement on both sides using a pain-rating scale. Descriptive statistics and a factorial repeated-measure analysis of variance were calculated for pain response, sex, and side of the jaw. RESULTS: At T1, T2, and T3, 1.0 mL of anesthetic had a lesser pain score by 1.00, 1.00, and 0.58, respectively, compared to 0.5 mL, with 95% confidence intervals of 0.43 to 1.57 (P = .001), 0.49 to 1.51 (P = .000), and 0.08 to 1.08 (P = .024), respectively. CONCLUSIONS: 1.0 mL of 2% lignocaine with 1:200,000 epinephrine administered submucosally appears to provide better anesthesia than 0.5 mL during and after insertion of mini-implants. This study will help the operator administer the correct volume of infiltrative anesthetic thereby improving pain response, alleviating patient anxiety, and providing a better patient experience during and immediately after mini-implant placement.

Sulfate-Reducing Bacteria in Patients Undergoing Fixed Orthodontic Treatment.

OBJECTIVES: The oral microbiological environment may be implicated in the corrosion of orthodontic metals. This study aimed to examine the prevalence of sulfate-reducing bacteria (SRB) in orthodontic patients undergoing fixed appliance treatment. METHODS: Sixty-nine orthodontic and 69 healthy non-orthodontic participants were enrolled in the study. Supragingival and subgingivaloral biofilm were collected and tested for the presence of SRB. The DNA extraction, polymerase chain reaction (PCR), and 16sRNA Sanger sequencing method was performed from the SRB-positive samples. The sequenced PCR products were analysed and compared with databases to identify the bacterial genus. RESULTS: Amongst 69 orthodontic patients, characteristic black precipitates developed in 14, indicating the presence of iron sulfides which demonstrates the likelihood of SRB. Alternatively, 2 out of 69 showed the presence of SRB in healthy non-orthodontic participants (controls). Desulfovibrio spp was confirmed by analyses of 16sRNA sequencing, which revealed that the SRB prevalence was 20% in the examined participants with orthodontic appliances. CONCLUSIONS: The prevalence of SRB was found to be significantly higher amongst orthodontic patients compared to non-orthodontic participants. Presence of stainless steel in the oral environment may have facilitated the colonisation of SRB.

In-Vitro Assessment of the Corrosion Potential of an Oral Strain of Sulfate-Reducing Bacteria on Metallic Orthodontic Materials.

AIM: Orthodontic literature is scant when it comes to microbial corrosion. The oral prevalence of many bacteria which are capable of causing microbial corrosion is reported in the dental literature. The aim of this study is to experimentally determine the corrosive potential of an oral strain of Sulfate-reducing bacteria. MATERIALS AND METHODS: Stainless steel (SS) bracket, stainless steel archwire, NiTi archwire, Titanium molybdenum (TMA) archwire, and titanium miniscrew were immersed in five media which included Artificial saliva (group I), Sulfate rich artificial saliva (group II), API agar medium specific for SRB (group III), AS + API medium+ bacterial strain (group IV), SRAS+ API medium+ bacterial strain (group V). The materials were then subjected to Scanning electron microscopy and energy-dispersive X-ray analysis (EDX). RESULTS: Materials in groups I, II, and III did not show any surface changes whereas materials in groups IV and V which contained the bacteria showed surface changes which were erosive patches suggestive of corrosion. EDX analyses were in line with similar findings. CONCLUSION: This in vitro study suggested that the oral strain of Sulfate-reducing bacteria was able to induce corrosive changes in the experimental setup.

Effect of Fluoridated Mouthwashes on Corrosion Property of Orthodontic Appliances: A Narrative Review.

OBJECTIVE: To analyze the effects of various fluoride agents on metallic orthodontic materials. DESIGN: PubMed, Google Scholar, and Embase were searched using keyword combinations such as fluoride mouthwash and orthodontic appliance and corrosion, fluoride and fixed appliance, and metal degradation. RESULTS: Of 315 articles, 20 were selected for inclusion in the review. All types of fluoride agents, especially the acidulated form of fluoride, seemed to influence the corrosion of orthodontic metallic appliances. CONCLUSION: Since most of the studies reported suggest that fluoride ions are capable of causing corrosion of metallic orthodontic appliances, attention should be paid while prescribing fluoride agents for orthodontic patients. The degree of corrosion seems to be directly correlated with the acidity of the medium and the concentration of fluoride ions. Co-Cr brackets are resistant to corrosion by fluoride while stainless steel and Ti brackets are susceptible. CLINICAL SIGNIFICANCE: It allows making the right choice while choosing the orthodontic brackets in relation to their susceptibility to corrosion by fluoride ions.

Comparison of two treatment protocols for intrusion and retraction of maxillary anterior teeth using mini-implants : A prospective clinical trial.

OBJECTIVE: The primary objective of this study was to compare the magnitude of incisor intrusion and retraction between two different treatment protocols and the secondary objective was to evaluate overall treatment effects. MATERIALS AND METHODS: Thirty-four patients with proclined upper anterior teeth, increased overbite, and incisal show were randomly assigned to two treatment groups (G1 and G2). Upper first premolar extractions were performed in all cases. In G1, space closure was performed with conventional straight-wire friction mechanics with NiTi (nickel titanium) coil springs placed on 0.019â€³â€¯× 0.025″ stainless steel wires in a 0.022 slot system with an additional intrusive force via a midline mini-implant. In G2, NiTi coil springs were placed from buccal mini-implants placed onto 0.016â€³â€¯× 0.022″ SS wires in a 0.022 slot system bilaterally. Lateral cephalograms and study models taken at the beginning and at the end of 6 months of treatment were assessed. RESULTS: Both groups showed a statistically significant mild maxillary incisor intrusion, reduction in overjet, overbite, incisal show and a reduction in lower anterior facial height. There was a mild intrusion of the maxillary first permanent molar in G2 (not significant). Mesial movement of the maxillary first permanent molar was noted in G1 but distal movement occurred in G2. Constriction of the entire maxillary arch was noted in G1, whereas constriction was seen in the molar region only in G2. Root resorption was noticed in both groups. CONCLUSION: Both groups produced comparable results. Except for molar control, all the results obtained were comparable between the two mechanics. Application of an intrusive force in the midline may be beneficial in patients treated with conventional straight-wire mechanics to treat increased overbite when anchorage requirement is not high.

Intrusion of the maxillary posterior teeth with a single buccal mini-implant positioned bilaterally in young adults with a tendency towards hyperdivergence: A clinical study.

BACKGROUND: Skeletal anchorage systems have been used for intrusion of the posterior teeth with satisfactory results. To achieve this, mini-implants are placed at anatomically challenging sites such as the palate or require several mini-implants to produce the desired effect. OBJECTIVE: To determine the magnitude of intrusion of the maxillary posterior teeth achieved on a continuous arch wire using a single buccal mini-implant placed bilaterally in young patients with a tendency towards hyperdivergence and to evaluate its influence on the skeletal, dental and soft-tissue structures. METHODS: A total of 17 patients with proclination of the anterior teeth, tendency towards hyperdivergence and clockwise rotation of the mandible were selected. First premolars were extracted as part of treatment protocol. A 0.022-MBT bracket prescription was used. Mini-implants were placed bilaterally on the buccal aspect at the mucogingival junction or slightly gingival to it between the maxillary second premolar and first permanent molar. A total of 200 g of intrusive force was placed from a continuous 0.019 × 0.025 inch stainless-steel arch wire to the mini-implant by means of an elastomeric thread on both sides. Lateral cephalograms and study models were taken before the start of intrusion and six months later. Parametric and non-parametric tests were done to assess treatment results. RESULTS: Significant intrusion was observed in the maxillary molar and premolar region with tendency towards intrusion in the anterior region. There was significant decrease in lower anterior facial height (LAFH) with anti-clockwise mandibular rotation, decrease in facial proportion index and total facial height. No changes were observed in the transverse plane. CONCLUSION: Intrusion of the permanent maxillary molar can be achieved on a continuous arch wire with a single buccal mini-implant placed bilaterally with improvement in facial aesthetics, especially in the vertical plane. This method may be beneficial in patients with borderline vertical discrepancy treated with conventional friction mechanics during space closure after first premolar extractions.

Assessing the Potential Association Between Microbes and Corrosion of Intra-Oral Metallic Alloy-Based Dental Appliances Through a Systematic Review of the Literature.

Objective: Systematic review assessing the association between oral microorganisms and corrosion of intra-oral metallic alloy-based dental appliances. Design: PubMed, Scopus, and Web of Science were searched using keyword combinations such as microbes and oral and corrosion; microbes and dental and corrosion; microorganisms and oral and corrosion; microorganisms and dental and corrosion. Results: Out of 141 articles, only 25 satisfied the selection criteria. Lactobacillus reuteri, Streptococcus mutans, Streptococcus sanguis, Streptococcus mitis, Streptococcus sobrinus, Streptococcus salivarius, sulfate-reducing bacteria, sulfate oxidizing bacteria, Veilonella, Actinomyces, Candida albicans were found to have a potential association with corrosion of intraoral metallic alloys such as stainless steel, titanium, nickel, cobalt-chromium, neodymium-iron-boron magnets, zirconia, amalgam, copper aluminum, and precious metal alloys. Conclusion: The included studies inferred an association between oral microorganisms and intra-oral metallic alloys-based dental appliances, although, it is vital to acknowledge that most studies in the review employed an in-vitro simulation of the intra-oral condition.

Systematic review on the genetic factors associated with skeletal Class II malocclusion.

AIM: The aim of this study is to review studies evaluating the role of genetics in skeletal class II malocclusion. OBJECTIVE: To assess the scientific evidence associating the role of genes in skeletal class II malocclusion. Materials and Methods: A complete search across the electronic database through PubMed, Cochrane, LILACS, BMC and manual hand search of orthodontic journals were done till May 2019. The keywords for the search included: "Genetics", "class II malocclusion", "maxillary prognathism", "mandibular retrognathism". DATA COLLECTION AND ANALYSIS: Studies were selected based on PRISMA guidelines. RESULTS: Articles were selected based on the inclusion and exclusion criteria. A total of 11 cross-sectional studies satisfied the inclusion criteria and were analyzed for the role of genes in skeletal class II malocclusion. Almost all the studies except for one revealed a positive correlation of genes with skeletal class II malocclusion. CONCLUSIONS: Out of the 11 studies included, a positive correlation of the genes with the skeletal II malocclusion was found in 10 studies. Genes FGFR2, MSX1, MATN1, MYOH1, ACTN3, GHR, KAT6B, HDAC4, AJUBA were found to be positively linked to skeletal class II malocclusion.

Distalization of the entire maxillary arch with mini-implants in the posterior palatal alveolus- A case report / Distalização de todo o arco maxilar com mini-implantes na região alveolar posterior palatina - Relato de caso

A 22 year old male patient reported to the hospital with a chief complaint of forwardly placed teeth. On examination patient had Angle's Class I malocclusion and proclination of the anterior teeth. There were signs of frictional keratosis on the buccal mucosa. Treatment plan was to extract the third molars alone and distalize the entire maxillary arch with palatal mini-implants. 0.022 MBT brackets were bonded on the buccal aspect. 0.019" x 0.025" stainless steel wire was placed sequentially. Mini-implants were placed on the posterior alveolus on the palatal surface of maxilla. Retractive force was applied from an attachment bonded on the palatal aspect of the maxillary canine. Patient was reviewed periodically. Comparison of pre-treatment and post-treatment results revealed that the entire maxillary arch intruded and translated distally with a counter-clockwise rotation of the mandible with reduction in LAFH. There was a mild reduction in inter-canine with marginal expansion in the premolar and molar region. An improvement in facial profile was noted with no sign of root resorption. Thus, the posterior alveolus may be considered as a new and appropriate site for placement of mini-implant to bring about distal movement of the entire maxillary dentition (AU)

Um Paciente do sexo masculino, 22 anos, foi encaminhado ao hospital com queixa principal de dentes posicionados para a frente. Ao exame clínico o paciente apresentava má oclusão de Classe I de Angle e inclinação vestibular dos dentes anteriores. Havia sinais de queratose friccional na mucosa bucal. O plano de tratamento foi extrair os terceiros molares e distalizar todo o arco maxilar com mini-implantes por palatino. Bráquetes MBT 0,022 foram colados por vestibular. Fio de aço inoxidável 0,019 "x 0,025" foi colocado seqüencialmente. Mini-implantes foram instalados na região alveolar posterior da superfície palatina da maxila. A força de retração foi aplicada a partir de acessórios colados nas faces palatinas dos caninos superiores. O paciente foi reavaliado periodicamente. Os resultados da comparação pré-tratamento e pós-tratamento revelaram que todo o arco maxilar intruiu e transladou distalmente com rotação da mandíbula no sentido anti-horário com redução da AFAI. Houve uma ligeira redução na distância intercanina com expansão marginal nas regiões de pré-molar e molar. Foi percebida melhora no perfil facial sem sinal de reabsorção radicular. Assim, a região alveolar posterior pode ser considerada como um novo e apropriado local para instalação de mini-implante para promover movimento distal de toda a dentição maxilar. (AU)

Orthodontic extrusion of Ellis Class VIII fracture of maxillary lateral incisor - The sling shot method.

The aim of this paper is to evaluate the efficacy of forced extrusion using the sling shot elastic. A 21 year adult patient reported with an Ellis Class VIII fracture of the maxillary right lateral incisor. Root canal treatment followed by a fiber reinforced composite post was placed and core build up was done. A metal button was bonded to the tooth. Begg brackets were placed from the second premolar on one side to the second premolar on the opposite side. 0.016″ × 0.025″ stainless steel was placed in ribbon mode. The ligature wire was placed as a sling shot from the button on the fractured tooth to the two adjacent teeth. 4 mm of extrusion was achieved and there was no evidence of root resorption. Forced extrusion was achieved in four months. The sling shot method is a very effective method of ligation. Light forces are delivered over a long duration with definitive results as compared to the inconsistent force delivery with conventional extrusion mechanics.

Quantification of intrusive/retraction force and moment generated during en-masse retraction of maxillary anterior teeth using mini-implants: A conceptual approach.

OBJECTIVE: The aim of the present study was to clarify the biomechanics of en-masse retraction of the upper anterior teeth and attempt to quantify the different forces and moments generated using mini-implants and to calculate the amount of applied force optimal for en-masse intrusion and retraction using mini-implants. METHODS: The optimum force required for en-masse intrusion and retraction can be calculated by using simple mathematical formulae. Depending on the position of the mini-implant and the relationship of the attachment to the center of resistance of the anterior segment, different clinical outcomes are encountered. Using certain mathematical formulae, accurate measurements of the magnitude of force and moment generated on the teeth can be calculated for each clinical outcome. RESULTS: Optimum force for en-masse intrusion and retraction of maxillary anterior teeth is 212 grams per side. Force applied at an angle of 5o to 16o from the occlusal plane produce intrusive and retraction force components that are within the physiologic limit. CONCLUSION: Different clinical outcomes are encountered depending on the position of the mini-implant and the length of the attachment. It is possible to calculate the forces and moments generated for any given magnitude of applied force. The orthodontist can apply the basic biomechanical principles mentioned in this study to calculate the forces and moments for different hypothetical clinical scenarios.

Orthodontic management of a dilacerated central incisor and partially impacted canine with unilateral extraction - A case report.

AIM: To align a dilacerated maxillary central incisor and partially impacted canine with unilateral extraction in a young patient with skeletal deep bite. MATERIALS AND METHODS: A 14 year old male patient reported to the hospital with skeletal deep bite (basal plane angle-17°), severe horizontal pattern of growth (Go-Gn to Sn -22°), upright maxillary incisors (U1 to NA -26°) and retroclined lower incisors (L1 to NB -11°). The maxillary left central incisor was dilacerated, and the maxillary left canine was partially impacted. Unilateral extraction of the left maxillary premolar and left mandibular central incisor was done. A canine disimpaction spring was used to align the impacted canine. An anterior bite plane was given to open the bite. RESULTS: Superimposition of lateral cephalogram (T1, T2) revealed bite opening, normal overjet and overbite. There was backward rotation of the mandible and increase in lower anterior facial height. There was no evidence of root resorption or loss of vitality in the dilacerated tooth. Clinically the canine was well aligned in the arch. CONCLUSION: Orthodontic management of a dilacerated incisor can be done without root resorption or loss of vitality. The partially impacted canine was well aligned in the arch. Unilateral extraction can produce good treatment results.

Quantification of intrusive/retraction force and moment generated during en-masse retraction of maxillary anterior teeth using mini-implants: A conceptual approach

ABSTRACT Objective: The aim of the present study was to clarify the biomechanics of en-masse retraction of the upper anterior teeth and attempt to quantify the different forces and moments generated using mini-implants and to calculate the amount of applied force optimal for en-masse intrusion and retraction using mini-implants. Methods: The optimum force required for en-masse intrusion and retraction can be calculated by using simple mathematical formulae. Depending on the position of the mini-implant and the relationship of the attachment to the center of resistance of the anterior segment, different clinical outcomes are encountered. Using certain mathematical formulae, accurate measurements of the magnitude of force and moment generated on the teeth can be calculated for each clinical outcome. Results: Optimum force for en-masse intrusion and retraction of maxillary anterior teeth is 212 grams per side. Force applied at an angle of 5o to 16o from the occlusal plane produce intrusive and retraction force components that are within the physiologic limit. Conclusion: Different clinical outcomes are encountered depending on the position of the mini-implant and the length of the attachment. It is possible to calculate the forces and moments generated for any given magnitude of applied force. The orthodontist can apply the basic biomechanical principles mentioned in this study to calculate the forces and moments for different hypothetical clinical scenarios.

RESUMO Objetivo: o objetivo do presente estudo foi explicar o funcionamento da biomecânica de retração em massa dos dentes anterossuperiores e tentar quantificar as diferentes forças e momentos gerados ao se usar mini-implantes, além de calcular a quantidade ideal de força a ser aplicada para se obter a intrusão/retração em massa ancorada em mini-implantes. Métodos: a força ideal necessária para se realizar a intrusão/retração em massa pode ser calculada por meio de fórmulas matemáticas simples. Dependendo da posição do mini-implante e da posição do acessório, a ele conectado, com relação ao centro de resistência do segmento anterior, obtêm-se desfechos clínicos diferentes. Aplicando certas fórmulas matemáticas, pode-se calcular com precisão a magnitude da força e do momento gerado nos dentes, para cada desfecho clínico. Resultados: a força ideal para se obter a intrusão/retração em massa dos dentes anterossuperiores é de 212 gramas por lado. A força aplicada em um ângulo de 5° a 16° em relação ao plano oclusal produz componentes de força de intrusão/retração que se encontram dentro dos limites fisiológicos. Conclusão: podem ser encontrados diferentes desfechos clínicos dependendo da posição do mini-implante e do comprimento do acessório. É possível calcular as forças e os momentos gerados para qualquer magnitude de força aplicada. Assim, o ortodontista clínico pode aplicar os princípios biomecânicos básicos apresentados nesse estudo para calcular as forças e os momentos em diferentes cenários clínicos hipotéticos.

The orthodontic extraction of permanent molars: a literature review.

The most common cause of dental crowding is the presence of an arch-length--tooth-size discrepancy. Conventional methods of gaining space in orthodontics involve the extraction of teeth, often premolars. However, there are a number of clinical situations in which the extraction of permanent molars might be considered. This paper highlights the indications, advantages, disadvantages and timing of the extraction of the first, second and third permanent molars in the treatment of a crowded malocclusion.

A simple three-dimensional stent for proper placement of mini-implant.

BACKGROUND: This paper deals with the fabrication of a three-dimensional stent which is simple in design but provides an accurate placement of a mini-implant in three planes of space, namely, sagittal (root proximity), vertical (attached gingiva/alveolar mucosa) and transverse (angulation). FINDINGS: The stent is made of 0.018×0.025 in. stainless steel archwire which consists of a 'u loop' angulated at 20°, a vertical limb, a horizontal limb and a stop. The angulation of the 'u' helps in the placement of the mini-implant at 70° to the long axis of the tooth. The vertical height is determined such that the mini-implant is placed at the mucogingival junction. The mini-implant is placed with the aid of the stent, and its angulation and proximity to the adjacent roots are checked with a cone beam computed tomography image. The cone beam computed tomography image showed the mini-implant at an angle of 70° to the long axis of the tooth. There is no contact between mini-implant and the roots of the adjacent teeth. CONCLUSION: This stent is simple, easy to fabricate, cost-effective, and provides ease of insertion/removal, and three-dimensional orientation of the mini-implant.

Determination of craniofacial relation among the subethnic Indian population: a modified approach (vertical evaluation).

AIM: To measure the vertical linear cephalometric dimensions of the anterior and posterior segments of the craniofacial complex and establish ratios between vertical linear dimensions in subjects with normal occlusion, pleasing profile, and facial harmony. SETTING AND SAMPLE POPULATION: Department of Orthodontics, Saveetha University. Lateral cephalograms of 120 subjects of both sexes in the age group of 17-28 years with normal occlusion belonging to Chennai, India. MATERIALS AND METHODS: The vertical segments measured are anterior maxilla, posterior maxilla, and ramus-cranial floor vertical. The facial heights were measured in the anterior and posterior region of the craniofacial complex. Establish ratios and proportions between the vertical segments and different facial heights. RESULTS: In both the sexes, the ratio between anterior maxilla, posterior maxilla, and ramus-cranial floor vertical is 1:1:1, PTFH:ATFH is 1:1, AUFH:ATFH is 2:5, ALFH:ATFH is 3:5, PUFH:PTFH is 1:2, PLFH:PTFH is 1:2, AUDH:ALDH is 2:3, and facial depth is 2:1. PUDH:PLDH is 7:9 in females and 3:4 in males. There was a statistically significant difference in posterior total facial height:anterior total facial height ratio between the two sexes with a "P" value of 95%. CONCLUSION: Thus, the anterior maxilla, posterior maxilla, and cranial floor-ramus vertical composite are in dimensional balance in subjects with normal occlusion and facial harmony. This analysis helps to identify skeletal deviations in size and position in the vertical dimension and allows the clinician to outline an appropriate treatment.