Miniscrew anchorage versus Class II elastics for maxillary arch distalization using clear aligners.

OBJECTIVES: To identify whether intramaxillary miniscrew anchorage could achieve a better maxillary arch distalization effect in clear aligner treatment compared to Class II elastics. MATERIALS AND METHODS: Thirty adult patients with Class II dentition who were treated with whole maxillary arch distalization using clear aligners were collected. Either intramaxillary miniscrew anchorage (miniscrew group, n = 17) or intermaxillary Class II elastics (Class II elastic group, n = 13) were used to support maxillary arch distalization. Three-dimensional predicted and achieved displacements, and angular changes of maxillary posterior teeth and anterior teeth, were measured and compared. RESULTS: The achieved distalization efficiency was 36.2%-43.9% in the posterior teeth and the retraction efficiency was 36.9%-49.4% in the anterior teeth. No statistically significant differences were found in maxillary arch distalization efficiency between the groups. The miniscrew group achieved less incisor extrusion and posterior tooth distal tipping than the Class II elastic group. Both groups achieved comparable arch expansion, posterior tooth buccal inclination, and anterior tooth lingual inclination. CONCLUSIONS: Intramaxillary miniscrew anchorage and intermaxillary Class II elastics achieved comparable efficiency in maxillary arch distalization. However, the miniscrew anchorage showed better vertical control in anterior teeth and mesiodistal tipping control in posterior teeth.

Evaluation of dentoalveolar changes following maxillary incisor intrusion with one vs two anterior miniscrews in subjects with gummy smile: a randomized clinical trial.

OBJECTIVES: To examine dentoalveolar changes following intrusion of maxillary incisors with one or two anterior miniscrews in subjects with gummy smile and deep bite. MATERIALS AND METHODS: Forty-three subjects were selected and divided into two groups: group I (22 subjects: 15 women, 7 men; mean age 30 ± 10 years) received one miniscrew between the upper central incisors, and group II (21 subjects: 16 women, 5 men; mean age 30 ± 10 years) received two miniscrews between the canines and lateral incisors. Dentoalveolar parameters, including amount of intrusion, root resorption, incisor inclination, alveolar bone thickness, and buccal alveolar crest height (cementoenamel junction to labial alveolar crest), were evaluated using cone-beam computed tomography scans obtained before and after intrusion. The intergroup comparison was analyzed using a paired t-test and unpaired t-test to determine significant changes within and between groups. RESULTS: The amount of intrusion was significantly greater in group II than in group I (P < .05). No statistically significant differences were found between groups I and II for changes in incisor inclination, labial bone thickness, and buccal alveolar crest height (P > .05). CONCLUSIONS: Maxillary central and lateral incisor intrusion was significantly greater in subjects treated with two miniscrews. Root resorption of the maxillary central incisors was notably greater in subjects with one miniscrew, while maxillary lateral incisor resorption was greater in subjects treated with two miniscrews.

Correction of a severe post-surgical iatrogenic class II anterior open bite with lingual appliances and mini-screws: a case report.

An iatrogenic open bite after orthognathic surgery is an uncommon malocclusion, with only one documented case reported in the literature. However, the open bite in this case report was not a true open bite, as it resulted from the interferences between the maxillary second molars and mandibular retromolar bones. This case report aims to present the management of a true iatrogenic open bite with posterior teeth in centric occlusion, occurring after mandibular setback surgery. The anterior open bite accompanied a severe class II malocclusion and increased lower anterior facial height. The patient was treated with fixed lingual appliances and mini-screws to distalize the entire maxillary arch and close the open bite. After treatment, a positive overbite and dental class I relationship was achieved. The treatment outcomes were stable at the 2-year follow-up. Lingual appliances combined with mini-screws may offer effective non-surgical management of iatrogenic open bite after orthognathic surgery. Clinical and Surgical Implications: Iatrogenic open bites can develop from various causes that include surgical options such as orthognathic surgery or in patients treated with occlusal splint therapy. These may be treated with the help of skeletal anchorage options such as orthodontic mini-screws.

Active vertical control with skeletal anchorage for optimizing facial profile in a severe Class II high-angle protrusion case.

This case report describes the nonsurgical management of a patient with a Class II skeletal pattern, retrognathic mandible, steep mandibular angle, maxillary vertical excess, and lip incompetence. The treatment approach involved orthodontic mechanics supported with skeletal anchorage to achieve maximal intrusion and retraction of the dentition. A novel elastic hanging rack appliance, supported by midpalatal miniscrews, was used. A maximal anchorage setup for active vertical control on both arches was illustrated. Significant improvement in the facial profile was achieved with optimal occlusion. Cephalometric analysis revealed successful incisor retraction and intrusion, as well as a forward rotation of the mandible. The treatment outcome illustrates the impact of active vertical control on orthodontic camouflage treatment for severe protrusion.

Post-condylectomy orthodontic treatment for a severe asymmetrical open bite in a condylar hyperplasia patient.

A satisfactory treatment of an 18-year-old lady was reported with right combination-type condylar hyperplasia (CH) in active phase. The chin severely deviated to the left, with the right gonial angle locating at a lower level. Intraorally, the lower centre line shifted to the left, the scale of which reached the width of one lower incisor. The right molar relation was mesial. Right maxillary second molar over-erupted without contact to lower teeth. There had been 2.5-mm anterior open bite (AOB) before surgery (T1) due to the tongue-spitting habit. After judging the benefits and disadvantages of all treatment alternatives, the decision was made to perform a right condylectomy and post-surgery orthodontics. Before orthodontics (T2) when the chin was positioned centred, an asymmetrical open bite occurred, caused by pre-contact between the right maxillary and mandibular second molars. Meanwhile, the AOB at T2 became 11.5mm. Orthodontic-related treatment included four premolars extraction and intrusion of bilateral maxillary molars using four miniscrews. Finally, this treatment achieved a clinically centred chin with two gonial angles at the same level. Post-condylectomy, the large AOB was resolved, together with a bilateral neutral molar relationship and alignment of the incisor midlines. Besides, the resected right condyle was covered by a continuous cortex bone and returned to the glenoid fossa. In sum, a high-challenging combined-type CH case was accomplished with impressive improvement in facial and occlusal symmetry, thanks to condylectomy and post-surgery miniscrew-assisted orthodontics.

Control of anterior anchorage with miniscrews and sliding mechanics in an adolescent with missing second premolars: A clinical report with biomechanical validation.

Congenital missing second premolars in growing patients should be accurately evaluated in order to establish a suitable treatment plan. Concerning the decision of whether to close or maintain spaces in the dental arches, it shall also be based on biomechanical aspects and the aesthetic traits of individual patients. Accordingly, the option of closing tooth spaces requires an adequate application of biomechanical principles aimed at avoiding detrimental effects on dental arches and facial profile. An effective use of titanium miniscrews for immediate loading, associated with efficient sliding mechanics, can represent an elective way to successfully treat such cases. Herein, the objective is to describe the procedure and underscore the advantages of the mentioned approach by presenting a clinical case along with long-term follow-up.

Investigation of Different Miniscrew Head Designs by Finite Element Analysis.

Objective: To determine the optimum miniscrew head design in orthodontic treatments for primary stability and compare stress distribution on a representative bone structure. Methods: Miniscrews with cross heads, mushroom-shaped heads, button heads, bracket heads, and through-hole heads were compared using finite element analysis. Miniscrews, whose three-dimensional drawings were completed using the SolidWorks computer-aided software package, were inserted in the bone block. Orthodontic force was applied to the head, and stress distributions, strains, and total deformations were investigated. Results: The lowest von Mises stress of 5.67 MPa was obtained using the bracket head. On the other hand, the highest von Mises stress of 22.4 MPa was found with the button head. Through mesh convergence analysis, the most appropriate mesh size was determined to be 0.5 mm; approximately 230,000 elements were formed for each model. Conclusion: Because the need for low stress is substantial for the primary stability of the miniscrew, this study demonstrated that the bracket head miniscrew is the optimal head design. In addition, it is posited that the success rate of orthodontic anchorage treatments will increase when bracket head miniscrews are used.

Assessment of Bone Thickness at the Infra Zygomatic Crest Region for Various Orthodontic Miniscrew Implant (OMSI) Insertion Angles: A Cone-Beam Computed Tomographic Study.

Objective: To evaluate the infrazygomatic crest (IZC) bone and develop guidelines for the optimum placement of orthodontic miniscrew implants (OMSIs) along the distobuccal root of the permanent maxillary first molar. Methods: Bone thickness of the IZC region of 50 young adults (25 males and 25 females) aged 18-30 years were evaluated using cone-beam computed tomography images. The infrazygomatic bone thickness along the distobuccal root of the permanent maxillary first molar was assessed at various insertion angles (40° to 75° i.r.t the maxillary occlusal plane) with an increment of 5°. Student's t-test was used to compare the IZC bone thickness and height at the orthodontic miniscrew insertion site for males and females on the right and left sides. Results: The bone thickness of the IZC region above the distobuccal root of the permanent maxillary first molar was estimated between 4.39±0.25 mm and 9.03±0.45 mm for insertion angles from 40° to 75° to the maxillary occlusal plane. The corresponding OMSI insertion heights were 17.71±0.61 mm to 13.69±0.75 mm, respectively, above the maxillary occlusal plane. There were statistically significant gender and side-wise variations in bone thickness at the IZC area and insertion height. Conclusion: The safe position for OMSI placement at the IZC was 13.69-16 mm from the maxillary occlusal plane with an insertion angle between 55° and 75°. These parameters provide the optimum placement of OMSIs along the distobuccal root of the permanent maxillary first molar.

Effect of cortical bone thickness on shear stress and force in orthodontic miniscrew-bone interface - A finite element analysis.

Miniscrews are widely used in orthodontics as an anchorage device while aligning teeth. Shear stress in the miniscrew-bone interface is an important factor when the miniscrew makes contact with the bone. The objective of this study was to analyze the shear stress and force in the screw-bone interface for varying Cortical Bone Thickness (CBT) using Finite Element Analysis (FEA). Varying CBT of 1.09 mm (1.09CBT) and 2.66 mm (2.66CBT) with miniscrews of Ø1.2 mm, 10 mm length (T1), Ø1.2 mm, 6 mm length (T2) and Ø1.6 mm, 8 mm length (T3) were analyzed. Six Finite Element (FE) models were developed with cortical, cancellous bone, miniscrews and gingiva as a prism. A deflection of 0.1 mm was applied on the neck of the miniscrews at 0°, +30° and -30° angles. The shear stress and force in the screw-bone interface were assessed. The results showed that the CBT affects the shear stress and force in the screw-bone interface region in addition to the screw dimensions and deflection angulations. T1 screw generated lesser shear stress in 1.09CBTand 2.66CBTcompared to T2 and T3 screws. Higher CBT is preferred for better primary stability in shear aspect. Clinically applied forces of 200 gms to 300 gms to an anchorage device induces shear stress in the miniscrew-bone interface region might cause stress shielding. Thus, clinicians need to consider the effect of varying CBT and the size of the miniscrews for the stability, reduced stress shielding and better anchorage during orthodontic treatment.

Successful treatment for an adult with bilateral posterior teeth crossbite by miniscrew-assisted rapid palatal expansion: A case report.

Key Clinical Message: Successful treatment by miniscrew-assisted rapid expansion and clinical aligner therapy for an adult diagnosed with maxillary transverse deficiency (MTD) by clinical examinations and Yonsei transverse analysis. Abstract: Adult orthodontic diagnosis and treatment with maxillary transverse deficiency (MTD) is challenging. Miniscrew-assisted rapid palatal expansion (MARPE) is a fast and low-risk method to expand the width of maxillary basal bone. This case report describes a 23-year-old female with mandible deviation and bilateral posterior teeth crossbite. She was diagnosed as MTD by the clinical examinations and Yonsei transverse analysis, and treated by the MARPE and clinical aligner therapy. After 26 months' treatment, cone-beam computed tomography (CBCT) images showed that the width of maxillary basal bone increased by 3.8 mm, that of zygomatic arch and nasal bone increased by 1.0 and 1.9 mm, respectively, and the bilateral posterior teeth crossbite was corrected. Furthermore, the dental midline of lower arch was consistent with that of upper arch and face, the molars arrived Angle Class II and canines was Class I relationships, the profile was maintained, the facial asymmetry was improved. The results of seventeen-month follow-up showed that the effect of orthodontic treatment is very stable. This case report demonstrates that MARPE is the effective approach for patients with MTD and facial asymmetry, which provide the alternative for the treatment of similar cases.

Tricortical versus bicortical anchorage in a double-screw tandem skeletal expander and a single-screw maxillary anchorage rapid palatal expander: A finite element analysis.

Objective: This study aims to employ finite element method (FEM) analysis to compare the differences between bicortical and tricortical anchorage of the posterior miniscrews in a single-screw miniscrew-assisted rapid palatal expansion (MARPE) and a double-screw tandem skeletal expander (TSE) under open and closed suture conditions. Methods: A cone beam computed tomography of the human skull of a 21.5-year-old female was utilized as a model for creating a FEM analysis. Simulations involved the insertion of four palatal miniscrews: two anterior ones with bicortical anchorage and two posterior ones (one with bicortical and another with tricortical anchorage), under open and closed suture conditions in a single-screw MARPE and double-screw TSE, resulting in a total of eight different simulation configurations. Evaluation parameters include total deformation (mm), Von Mises stress (MPa), and strain for each miniscrew body. Results: Tricortical anchorage of the posterior miniscrews provides greater anchorage, higher stress, and deformation on the anterior miniscrews in single-screw MARPE. Tricortical anchorage combined with a double-screw TSE promotes a more even distribution of force and stress on miniscrews under open suture conditions, leading to a parallel midpalatal suture opening along its entire length and height. Conclusions: FEM analysis revealed favorable midpalatal suture opening with equal force distribution and less stress when posterior tricortical anchorage in conjunction with double-screw TSE is applied.

Is motor-driven insertion of orthodontic miniscrews more advantageous than manual insertion? A micro-CT evaluation of bone miniscrew contact surface area and cortical microcracks in rabbits.

AIM: This in vitro study aimed to evaluate and compare the bone-miniscrew contact surface area (BMC) and the cortical bone microcracks (CM) resulting from manual (hand-driven) and automated (motor-driven) orthodontic miniscrew (OM) insertion methods. METHODS: Thirty-three OM were inserted in the femurs of nine New Zealand rabbits using manual (n = 16) and automated (n = 17) insertions. After euthanizing the rabbits, bone blocks, each including one OM, were sawed. Micro-CT scanning was performed, and data analysis included reconstruction, binarization and quantification of morphometric parameters of BMC and the number and length of CM. Means and standard deviations for complete BMC, complete BMC proportion, cortical BMC, cortical BMC proportion, and length and number of CM were calculated. Mixed model analysis was used to adjust for more than one sample/CM per animal. A paired t-test was used to compare the number of CM between the two groups. RESULTS: Compared to the automated insertion, manually inserted miniscrews had significantly lower complete BMC (7.54 ± 1.80 mm2 vs. 11.99 ± 3.64 mm2), cortical BMC (5.91 ± 1.48 mm2 vs. 8.48 ± 1.90 mm2) and cortical BMC proportion (79.44 ± 5.84% vs. 87.94 ± 3.66%). However, it was not statistically significant in complete BMC proportion (p = .052). The automated insertion also resulted in a significantly lower mean number of CM than the manual method (p = .012). However, the length of the cracks was shorter in the manual group but with no significant difference (p = 0.256). CONCLUSION: Motor-driven OM insertion results in superior BMC and reduction in the number of CM, which may lead to better miniscrew stability.

The Fabrication of a Customized Surgical Template for a Miniscrew Placement Using a Fully Digitized Process.

This report presents a clinical case involving the application of a computer-aided design and manufacturing (CAD-CAM) guide to insert miniscrew anchorage at the zygomatic alveolar ridge. A 24-year-old male adult came in with overcrowded teeth and a protruding facial profile, particularly severe overcrowding in the upper teeth and moderate overcrowding in the lower teeth. The orthodontic treatment plan involved extracting four first premolars and adding a mini-implant in the upper jaw to enhance anchorage. A miniscrew was placed in the patient's left zygomatic alveolar ridge using a guide and in the right zygomatic alveolar ridge based on experience. The use of a mini-implant guide improves the accuracy of mini-implant positioning and angulation in the infrazygomatic crest zone, reduces the risk of tooth root damage, and enhances mini-implant stability.

Image fusion-based low-dose CBCT enhancement method for visualizing miniscrew insertion in the infrazygomatic crest.

Digital dental technology covers oral cone-beam computed tomography (CBCT) image processing and low-dose CBCT dental applications. A low-dose CBCT image enhancement method based on image fusion is proposed to address the need for subzygomatic small screw insertion. Specifically, firstly, a sharpening correction module is proposed, where the CBCT image is sharpened to compensate for the loss of details in the underexposed/over-exposed region. Secondly, a visibility restoration module based on type II fuzzy sets is designed, and a contrast enhancement module using curve transformation is designed. In addition to this, we propose a perceptual fusion module that fuses visibility and contrast of oral CBCT images. As a result, the problems of overexposure/underexposure, low visibility, and low contrast that occur in oral CBCT images can be effectively addressed with consistent interpretability. The proposed algorithm was analyzed in comparison experiments with a variety of algorithms, as well as ablation experiments. After analysis, compared with advanced enhancement algorithms, this algorithm achieved excellent results in low-dose CBCT enhancement and effective observation of subzygomatic small screw implantation. Compared with the best performing method, the evaluation metric is 0.07-2 higher on both datasets. The project can be found at: https://github.com/sunpeipei2024/low-dose-CBCT .

Biomechanical Multipurpose Miniscrew Strategy for Simultaneous Distalization in Class II Patients-The BiGa System.

An efficient treatment plan using a temporary anchorage device should be built following the principle of reducing the number of tads to obtain a multiple biomechanical advantage. The following case report concerns the Biga system, a strategy that supports orthodontists during class II corrections and vertical control through treatment. A 12-year-old girl with a high angle of skeletal class II was selected. A novel biomechanical strategy was effectively applied using two tads on the upper arch to obtain sequential distalization of the upper teeth and to correct the lower arch spee curve using third-class elastics. Eventually, on the same tads, a double cantilever was applied to control the overbite and intrusion during incisors' retraction. The Biga system is an easy biomechanical strategy that ensures the three-dimensional control of treatment mechanics in class II patients.

How palatal vault morphology and screw length influence the accuracy of dynamic computer-guided orthodontic miniscrew insertion. A prospective clinical study.

OBJECTIVES: The aim of this study was to evaluate the influence of palatal vault morphology and screw length on the accuracy of miniscrew insertion in dynamic computer-assisted surgery (d-CAS). METHODS: Twenty-four subjects were allocated into three groups, according to their palatal vault morphology (Group A: medium; Group B: steep/high; Group C: low/flat) and the length of miniscrew used. For each subject, two miniscrews were inserted using a dynamic navigation system. To assess the accuracy of insertion, a postoperative CBCT was performed, and the pre- and post-operative scans were superimposed. Five variables were evaluated: Entry-3D, Entry-2D, Apex-3D, Apex-vertical and angular deviation. Descriptive statistics, Shapiro-wilk, Kruskal-Wallis and Dunn's tests were used for the statistical analysis. The level of significance was P ≤ 0.05. RESULTS: The mean angular deviation values revealed strong discrepancies amongst the groups (Group A:7.11°±5.70°; Group B:13.30°±7.76°; Group C:4.92°±3.15°) and significant differences were found regarding the Apex-3D (P = 0.036) and angular deviations (P = 0.008). A Dunn's test revealed differences in angular deviation between the medium and high/steep palate group (P = 0.004), and between low/flat and high/steep palate group (P = 0.01) but did not confirm any significant difference in the Apex-3D parameter (Group A-B P = 0.10; Group B-C, P = 0.053; Group A-C, P = 1.00). No significant differences were found regarding the length of the miniscrews. CONCLUSIONS: Palatal vault morphology is a factor that influences the accuracy of miniscrew insertion in d-CAS. In subjects with steep and high palatal vaults, insertion accuracy is lower when considering the angular deviation value. Miniscrew length does not influence accuracy. CLINICAL SIGNIFICANCE: Although computer-guided surgery assists the clinician in preventing damage to nearby anatomical structures, individual anatomical variability is a crucial variable. In subjects with a high/steep palate, greater attention should be paid during the planning phase in order to allow for a wide margin from adjacent anatomical structures to achieve better outcomes.

Global scholarly output on orthodontic temporary anchorage devices (TADs): A silver jublee scientometric analysis.

OBJECTIVES: This study aimed to analyze the global scholarly production of articles related to temporary anchorage devices (TADs) from 1998-2023 in peer-reviewed dental journals indexed in the Web of Science. MATERIALS AND METHODS: A database of TADs-related articles was created via a Web of Sciences structured search. The bibliometric characteristics of the studies, including the number of citations, publication year, journal title, journal impact factor (IF), authorship, contributing institutions and countries, thematic field, and study design, were extracted. Keyword co-occurrence network analyses and the correlation between the number of citations and the article age, journal IF, and journal quartile of each article were performed. RESULTS: The top 50 cited articles were published from 1999-2016, and the total number of citations ranged from 82-602, with 160.36 citations/paper on average. Most of the articles originated from Japan (n = 12), with the most remarkable contributions from Nihon and Okayama Universities, Japan (n = 5, each). The American Journal of Orthodontics and Dentofacial Orthopedics had the most cited articles, with 196.57 citations/paper on average. A significant positive correlation occurred between the number of citations and publication age (rho = 0.392, P = 0.005). CONCLUSION: Our scientometric analysis reported the characteristics of TADs-related articles published over 25 years. Most highly-cited articles were published between 2005 and 2008. The positive correlation between articles' publication date and the number of citations might impact the top 50 within the next 5-10 years.

Mini-Screw-Assisted Orthodontic Retraction of Class I Malocclusion in a Bimaxillary Protrusion Patient Using Sliding Mechanics: A Case Report.

A condition known as bimaxillary protrusion occurs when the front teeth protrude due to the forward positioning of the lower and upper jaws. Temporary anchorage devices (TADs) are utilized to provide anchorage and facilitate the controlled retraction of maxillary and mandibular protruding teeth, helping to correct the patient's bite and facial aesthetics. A 27-year-old female with bimaxillary protrusion reported to the Department of Orthodontics. On examination, the facial profile of the patient was convex. The clinical FMA was high. With a deep mentolabial sulcus and an acute nasolabial angle, lips were potentially competent. An intraoral examination revealed proclined incisors with spacing in the maxillary arch and proclined anterior teeth in the mandibular arch. Space closure was done using sliding mechanics with direct anchorage from a mini-screw after the extraction of all four first premolars. There was a significant improvement in the patient's profile posttreatment.

Effectiveness of Miniscrew-Supported Molar Intrusion: A Clinical Study.

Mini-screws, also known as temporary anchorage devices (TADs), offer enhanced control and versatility in orthodontic treatment by providing stable anchorage points. This clinical study aims to evaluate the effectiveness of mini-screw-supported molar intrusion in orthodontic practice. For this clinical study, a cohort of 40 orthodontic patients with various malocclusions requiring molar intrusion as part of their treatment plan was recruited. The age range of the participants spanned from 14 to 35 years, representing a diverse patient population. The intervention involved the implementation of mini-screw-supported molar intrusion on one side of the maxillary arch in each patient. To achieve this, temporary mini-screws were strategically placed, and a combination of orthodontic forces and mini-screw anchorage was employed to intrude the molars. The primary outcome measure for this study was the amount of molar intrusion achieved, which was quantified in millimeters from the initial evaluation to the final visit. Additionally, the duration of treatment required to achieve the desired molar intrusion was recorded in months. The results of this clinical study demonstrated that mini-screw-supported molar intrusion was an effective and safe orthodontic technique. On average, a significant mean molar intrusion amount of 4.8 mm (standard deviation [SD] ± 0.6) was achieved with the mini-screw-supported approach. Furthermore, the treatment duration required to attain the desired molar intrusion was relatively short, with a mean of 6.2 months (SD ± 1.1). In conclusion, this clinical study provides evidence that mini-screw-supported molar intrusion is an effective and safe approach in orthodontic practice. It offers orthodontists the advantage of enhanced control and predictability in molar intrusion procedures.

Risk factors and treatments for impacted permanent second molars.

Background/purpose: Impaction of permanent second molar (PM2) is found occasionally. This study tried to explore the risk factors associated with the impacted PM2 teeth and show how to use different treatment modalities to correct the impaction of PM2 teeth. Materials and methods: This study used three cases of PM2 impaction to show how to identify the risk factors of PM2 impaction and how to remove these risk factors to facilitate the eruption of impacted PM2 teeth to the correct occlusal positions. Results: The first and second cases both showed delayed eruptions of two maxillary PM2 teeth. After resection of the dense fibrotic gingival tissues on the tooth eruption pathway, these two impacted maxillary PM2 teeth finally erupted to the normal occlusal positions by their inherent tooth eruption potential. The second case also had mesioangular impaction of two mandibular PM2 teeth. After odontectomy of teeth 38 and 48, the two impacted mandibular PM2 teeth also erupted to the normal occlusal positions by their inherent tooth eruption potential. The third case had impaction of teeth 17, 27 and 47. After extraction of four third molars and four selected premolars, orthodontic mesialization of four permanent first molars, and orthodontic traction using a mini-screw, the three impacted teeth finally erupted to the normal occlusal positions. Conclusion: We conclude that after removing the obstacles on the tooth eruption pathway, the impacted PM2 teeth usually can erupt to their normal occlusal positions by their inherent tooth eruption potential with or without the assistance of orthodontic traction.