Retrospective comparison of two different miniscrew-supported molar distalization methods applied in the buccal and palatal regions.

BACKGROUND: To compare dentofacial effects of distalization with miniscrew-supported pendulum and infrazygomatic crest miniscrews. METHODS: The study included 36 patients whose lateral cephalometric radiographs were obtained before (T0) and after (T1) distalization. Patients were divided into two groups according to the treatment methods: 1) distalization with miniscrew-supported pendulum (MSP) (n = 19; 14 girls and 5 boys; mean age 16.9 ± 1.46 years) and 2) distalization with infrazygomatic crest (IZC) miniscrews (n = 17; 8 girls and 9 boys; mean age 17.0 ± 1.68 years). Dental, skeletal and soft tissue measurements were performed on lateral cephalograms taken from individuals. RESULTS: A significant molar distalization was achieved both in the MSP group (3.52 ± 0.76 mm at 8.71 ± 2.02 months) and the IZC group (3.5 ± 0.74 mm at 9.7 ± 2.5 months) (P < 0.001 for both). Premolar distalization was significantly lower in the MSP group (1.73 ± 1.09 mm) than in the IZC group (2.81 ± 0.79 mm) (P < 0.01). Significant molar tipping was observed in both groups (P < 0.001), while no significant difference was found between the groups (P > 0.05). Retrusion of maxillary incisors were significantly higher in the IZC group (2.75 mm) than in the MSP group (0.98 mm) (P < 0.01). A significant difference was found between the two groups with regard to the changes in overjet and overbite (P < 0.05). CONCLUSIONS: Both distalization methods were found to be effective in achieving a Class I molar relationship in patients with Class II malocclusion.

Comparison of treatment effects during en-masse retraction of upper anterior teeth placed using mini-implants placed at infrazygomatic crest and interradicular sites: A randomized controlled trial.

INTRODUCTION: The objective of this prospective study was to examine the efficacy of posterior interradicular and infrazygomatic crest mini-implants for en-masse anterior retraction. METHODS: The 22 patients were divided into two groups. In group 1 (IZC n = 11), mini-implants were placed in the infrazygomatic crests and in group 2 (IR, n = 11), mini-implants were placed in the molar-premolar interradicular sites. Soft tissue, skeletal, and dental treatment effects between two groups were compared using lateral cephalometric measurements. RESULTS: The average angle between the cranial base and A point was 1.01 degrees (P = .004), and the linear distance between the upper incisor and A point was 2.67 to 5.2 millimetres (P = .00). In IZC group the maxillary incisor to the palatal plane moved upward by a mean of -5.20 mm (P = .059), whereas in IR group the incisor movement changed by -2.67 mm (P = .068). There was no significant difference between groups IZC and IR while comparing overall treatment changes on upper incisor position change, angle, and overjet. CONCLUSIONS: Mini-implants placed in between the molar and premolar as well as the infrazygomatic crest can withstand the deepening of the bite during retraction. Mini-implants in IZC are capable of causing intrusion of the anterior teeth and preventing intrusion of the molars, thereby providing absolute anchoring in all planes. Placement of the mini-implants in the infrazygomatic crest resulted in more linear retraction.

Skeletal Anchorage Augmentation in Extraction/Nonextraction Orthodontic Treatment: A Randomized Clinical Study.

AIM: To evaluate and compare skeletal, dental, and soft tissue parameters by therapeutic extraction of first premolar and nonextraction distalization of maxillary and mandibular arches in bimaxillary proclination using the skeletal anchorage system. MATERIALS AND METHODS: About 40 orthodontic patients undergoing extraction or nonextraction treatment are enrolled in a randomized clinical trial. Participants are randomly assigned to either the extraction or nonextraction group and receive treatment augmented with skeletal anchorage. Mini implants were placed in the extraction group for retraction and infra-zygomatic crest (IZC) and buccal shelf screws were placed in the nonextraction group for distalization. OBSERVATIONS AND RESULTS: Comparison between the ages of the patients among both Groups showed no significant difference. A significant difference is observed in dental and soft tissue parameters before and after the treatment in group A, whereas skeletal parameters also showed significant changes along with dental and soft tissue parameters in group B. CONCLUSION: There is a significant change in the position of incisors by retraction and facial profile improves gradually in group A while for group B, a marked change in lower facial height was even seen. On comparing both the groups, a highly significant difference can be seen with respect to the amount of incisor retraction and change in molar inclination. The time taken for retraction of incisors is less in comparison to distalization. CLINICAL SIGNIFICANCE: With this, we can easily avoid premolar extraction, and in cases of impacted third molars distalization as when indicated can be helpful as a part of the nonextraction treatment plan.

Complications of Poly-l-Lactic Acid and Polyglycolic Acid (PLLA/PGA) Osteosynthesis Systems for Maxillofacial Surgery: A Retrospective Clinical Investigation.

Two second-generation PLLA/PGA bioresorbable osteosynthetic plate systems for oral and maxillofacial surgery are available in Japan. The two systems have different PLLA-PGA component ratios (RapidSorb®, 85:15; Lactosorb®, 82:18) and plate and screw shapes. We conducted a retrospective study to compare our clinical evaluation and examine the incidence of postoperative complications between the two plate systems. A retrospective survey was conducted in 148 patients (midfacial fracture/trauma (68.2%) and dentofacial deformity patients (31.8%); males (54.7%); median age, 37.5 years) treated using maxillofacial osteosynthetic plate systems. The complications included plate exposure (7.4%), infection, (2.7%), and plate breakage (0.7%). Multivariate logistic regression analysis showed a significant correlation between sex (female), plate system (Lactosorb®), number of plates, and pyriform aperture and periorbital sites of plate placement (p < 0.05). Additionally, the propensity score-adjusted model showed a significant correlation between Lactosorb® and postoperative complications (odds ratio 1.007 (95% confidence interval, 1.001-1.055), p < 0.01). However, the two plate systems showed a low incidence rate of complications, and the plate integration and survivability were similar using 2.0-mm or 1.5-mm resorbable plate regardless of the plate system. Our findings suggest that female sex and a greater number of plates are risk factors for postoperative complications, whereas pyriform aperture and periorbital plate placements reduce the risk.

Stress distribution patterns in mini-implant and bone in the infra-zygomatic crest region at different angulations: A finite element study.

PURPOSE: To evaluate, using the finite element method (FEM), von Mises stress patterns produced both in a mini-implant (MI) and the infra-zygomatic crest region (IZC) at different placement angles and force magnitudes. MATERIAL AND METHODS: FEM modeling of an infra-zygomatic crest MI, of dimensions 2 mm × 12 mm, was designed and placed in the IZC bone. The MI was inserted at 50°, 60°, 70°, 80°, and 90° angulations to the IZC surface. Simulated orthodontic forces of magnitudes 8, 9, 10, 11, and 12 oz were applied to the MI head. Von Mises stress and magnitude both in the MI and surrounding bone were measured. RESULTS: Von Mises stress in the MI and bone was maximum at 90°. Least stresses were observed at 50° and 60° angulations. As force magnitude increased, von Mises stress increased linearly. Maximum stresses in the MI and bone were observed when loads were 12 oz and minimum stresses were observed at 8 oz. CONCLUSION: To achieve optimum primary stability, angles of insertion between 50° and 60° are recommended in the IZC region. Highest von Mises stress values were detected in the MI, followed by cortical and cancellous bone. Also, loading force between 8 and 12 oz exerted stresses below the tolerable threshold of bone and MI. Hence, proper placement of MI in IZC using these findings might provide better biomechanical stability during retraction and may help in preserving the bone-implant interface.

Orthodontic bone screws: A quick update and its promising future.

Orthodontic bone screws (OBSs) provide intraoral anchorage by penetrating oral mucosa and seating firmly in basilar bone (BB). Retromolar (prosthetic-type) implants introduced the extra-alveolar (E-A) concept for BB anchorage to move teeth throughout the alveolar process, but the clinical procedures were complex and expensive. Titanium alloy (Ti) miniscrews placed in inter-radicular (I-R) alveolar bone are more convenient and provide some tooth movement potential, but multiple screws are usually required and the devices often interfere with the path of tooth movement. The advantages of BB anchorage and the convenience of miniscrew are combined into the E-A OBS system. These miniscrews are relatively large in diameter (2 mm), and strong (stainless steel), which are placed intraorally in the BB of the infra-zygomatic crest (IZC) and mandibular buccal shelf (MBS). E-A OBSs provide osseous anchorage to retract the dentition and/or rotate either arch. Recovery of impactions is effectively managed with lever arm springs anchored with IZC or MBS bone screws. An emerging frontier is BB anchorage for correcting severe malocclusions with clear aligners. Since the osseous-anchored mechanics are complementary, fixed appliances and clear aligners can be used individually or in tandem to resolve a broad variety of malocclusions. This report summarizes current concepts for conservatively managing complex malocclusions such as severe crowding, skeletal discrepancies, asymmetries and impactions with the OBS system.

Tratamento da Classe II-1 subdivisão, utilizando miniparafuso extra-alveolar no izc e aparelhos autoligáveis passivos ­ relato de caso / Class II-1 subdivision treatment using extra-alveolar mini screw in izc and passive self-ligating brackets ­ case report

As más oclusões de Classe II de Angle, de natureza dento-alveolar ou esquelética moderada, podem ser tratadas com ou sem exodontias de pré-molares, utilizando diversos recursos para ancoragem. O advento dos miniparafusos possibilitou uma ancoragem esquelética na distalização de molares, anulando os efeitos colaterais indesejados, por meio de um procedimento minimamente invasivo. Os parafusos extra-alveolares eliminaram ainda o inconveniente do posicionamento do corpo dos parafusos entre as raízes, permitindo maiores movimentos sagitais, sem a necessidade de reposicionamento dos miniparafusos ou utilização de cursores. Esse fato aumentou a eficiência do tratamento nas correções sagitais e simplificou a mecânica ortodôntica. A associação desse recurso de ancoragem com os aparelhos autoligáveis passivos com prescrições variáveis reduzem a quantidade de consultas, os níveis de força aplicada, necessidade de dobras no arco e a dependência de colaboração do paciente. Objetivo: Relatar um caso clínico no qual foi utilizado parafuso extra-alveolar na crista-infrazigomática como recurso de ancoragem, associado a aparelhos autoligáveis passivos na correção da Classe II-1 subdivisão direita. Conclusão: A associação dos parafusos extra-alveolares com o sistema de aparelhos autoligáveis passivos com prescrições variadas se mostraram eficientes na correção da má oclusão de Classe II subdivisão (AU)

Abstract Introduction: Angle Class II dentoalveolar or moderate skeletal malocclusions can be treated with or without premolar extraction using a variety of anchoring features. The advent of mini-screws allowed skeletal anchorage in molar distalization, nullifying unwanted side effects through a minimally invasive procedure. The extra-alveolar screws also eliminated the inconvenience of positioning the body of the screws between the roots, enabling greater sagittal movements, dispensing replacement of the mini-screws or cursors use. This fact increased treatment efficiency of sagittal corrections and simplified orthodontic mechanics. The association of this anchorage feature with passive self-ligating brackets reduces the number of consultations, the levels of applied force, the need for arch bending, and dependence of patient's collaboration. Objective: To report a clinical case in which the extra-alveolar screw was used in the IZC as an anchorage resource, associated with passive self-ligating brackets for the correction of Class II-1 subdivision. Conclusion: The association of extra-alveolar screws with passive self-ligating brackets system proved to be efficient in Class II subdivision malocclusion correction. (AU)