Miniscrew Insertion Research Articles

Safe sites in the mandibular buccal shelf for orthodontic mini-screws: Tomographic study in different facial types

Objectives: The objective of this study was to verify safe sites on the mandibular buccal shelf (MBS) for extra-alveolar mini-screw insertion according to facial type. Material and Methods: In this retrospective study, 84 cone-beam computed tomography scans were equally divided into three groups according to the patient’s facial type: Group 1, hyperdivergent; Group 2, neutral; and Group 3, hypodivergent. The total buccal alveolar bone thickness was measured in five zones between the mesial root of the first molar and the distal root of the second molar, 3, 6, and 9 mm apical to the cementoenamel junction (CEJ). Results: MBS areas with adequate thickness for temporary anchorage device (TAD) insertion were as follows: Group 1, second molar distal root 9 mm from the CEJ; Group 2, second molar distal root 6 and 9 mm from the CEJ; and Group 3, second molar mesial root 9 mm from the CEJ and second molar distal root 6 and 9 mm from the CEJ. Conclusion: The safe zones on the MBS for TAD insertion were located on the distal root of the second molar, 9 mm from the CEJ, for all facial types. For neutral and hypodivergent patients, the site located on the second molar distal root, 6 mm from CEJ, was included; for hypodivergent patients, the site located on the second molar mesial root, 9 mm from the CEJ, was included.

Evaluation Of Bone Thickness At Different Anatomical Sites In Infrazygomatic Crest For Miniscrew Insertion In Skeletal Class II Patients – A CBCT Study

AIM: To assess infrazygomatic crest bone thickness at different anatomical sites at a distance of 5mm, 7mm, 9mm and 11mm apical to cementoenamel junction, 70 degree to occlusal plane in skeletal class II patients using cone beam computed tomography (CBCT). Materials and Methods: The sample consists of cone beam computed tomography images of 23 class II subjects were evaluated. Infrazygomatic crest bone thickness was evaluated at the six horizontal regions (i) interdental area between maxillary second premolar (PM2) and first molar(M1) (ii) Mesiobuccal root of maxillary first molar (MB root of M1) (iii) Distobuccal root of maxillary first molar(DB root of M1) (iv) interdental area between maxillary first molar(M1) and second molar(M2) (v) Mesiobuccal root of maxillary second molar(MB root of M2) (vi) Distobuccal root of maxillary second molar (DB root of M2) at a vertical distance of 5mm,7mm,9mm and 11mm apical to cementoenamel junction, 70 degree to occlusal plane. Results: The buccal bone thickness increase from mesial surface of maxillary first molar to mesial surface of maxillary second molar from cement enamel junction at the level of 11mm, 70 degree to the occlusal plane. The bone thickness decreases at the second molar level. Conclusion: The safe site for insertion of miniscrews in the infrazygomatic crest were the interdental region between the maxillary first and second molars at the heights of 11 mm from cementoenamel junction and 70 degree to the occlusal plane

Comparative Evaluation Of Different Anatomical Sites In Buccal Shelf Region For Mini Screw Insertion In Skeletal Class II And Class III Patients-A CBCT Study

Background: To evaluate different anatomical sites in buccal shelf region at different levels (4mm, 6mm, 8mm, 10mm) from cemento-enamel junction for mini screw insertion in skeletal class II and class III patients using cone beam computed tomography (CBCT). Materials and Methods: The sample consists of cone beam computed tomography images of 48 subjects (24 skeletal class II and 24 skeletal class III) were evaluated. Mandibular buccal shelf area was evaluated at the regions (i) mesial to lower first molar (ML6) (ii) between the mesiodistal roots of the first molar (iii) distal to lower first molar (DL6) (iv) mesial to lower second molar (ML7) (v) between mesiodistal roots of the second molar (vi) distal to lower second molar (DL7) and cortical bone thickness was determined at 4, 6, 8, 10 mm level from cemento-enamel junction Results: Mandibular buccal shelf bone thickness increases from mesial surface of first molar to distal surface of second molar and from cemento-enamel junction to 8 mm level. Comparative evaluation between class II and class III shows significant differences (p<0.05) at the level of 8mm distal to second molar in the mandibular buccal shelf region. Conclusion: Skeletal class III subjects have more cortical bone thickness than class II subjects at the level of 8mm distal to second molar in the buccal shelf region.

An in vitro study of a combined patient-specific device for safe and accurate insertion of infrazygomatic crest miniscrews.

To develop and assess the efficacy of a novel combined patient-specific device (CPSD) for the accurate and safe insertion of infrazygomatic crest miniscrews in orthodontic procedures. Twenty-eight miniscrews were placed in the infrazygomatic crest region of 28 cadaver maxillae using the direct manual method (n = 14) or the CPSD (n = 14) based on preset trajectories. The CPSD, designed based on the integration model, included a positioning guide, an insertion guide, and a depth-limiting groove. Deviations in the insertion site, tip location, insertion angle, and biting depth between the preset and real insertion trajectories were calculated to evaluate the accuracy of miniscrew insertion. Classification frequencies of root proximity, sinus penetration depth, and biting depth of the miniscrew after insertion were also calculated to evaluate the safety of miniscrew insertion. Regarding evaluation of accuracy, significant differences were observed in the deviation values of the insertion site, tip location, insertion angle, and biting depth between the CPSD and freehand groups (P = .001, P < .001, P < .001, P = .039, respectively). Regarding evaluation of safety, a significant difference was observed in the classification frequencies of root proximity between the two groups (P = .016). Compared with manual insertion, CPSD could be a preferred method for safe and accurate insertion of infrazygomatic crest miniscrews for orthodontists.

3D printing: Changing the landscape of orthodontics

This paper aims to elucidate how three-dimensional (3D) printing technology has greatly impacted orthodontic practice, marking a significant advancement in planning treatment, fabricating appliances, and patient care. The integration of digital technologies, such as digital cephalogram, digital photography, intraoral and facial scanners, desktop scanners, cone-beam computed tomography (CBCT), and 3D printing, has significantly enhanced the efficiency, accuracy, consistency, and predictability of treatment outcomes. The advent of 3D printing in dental and orthodontic treatment has introduced a new era marked by precision, efficiency, and customised appliances, empowering practitioners to achieve superior results for their patients. Some of its applications in orthodontics include manufacturing clear aligner trays, surgical guides for miniscrew insertion and corticotomy, splints for orthognathic surgery, and retainers.

Three-dimensional assessment of low-level laser therapy on orthodontic miniscrew displacement using CBCT: a retrospective study

BackgroundThis study aimed to assess the effect of Low-Level Laser Therapy (LLLT) on sagittal, transverse and vertical Orthodontic miniscrew displacement.Materials and methodsThe study included CBCTs from the records of 12 adult patients who underwent upper first premolar extraction and canine retraction with orthodontic miniscrews for maximum anchorage. The miniscrews on one side received LLL, while the other side served as a control. The Low-Level Laser was applied to assess its effect on the displacement of the miniscrews. The used CBCTs have been taken at two-time points: immediately after miniscrew insertion (T0) and four months after the start of canine retraction (T1) with a total of 24 CBCTs. Miniscrew displacement was assessed by measuring head (HMS) and tail (TMS) displacement to the axial, coronal and mid-sagittal planes on the CBCT at the two time points. Miniscrews displacement (T1-T0) was compared between LLL side and control side. Comparisons were performed using paired samples t-test. The significance level was set at p-value < 0.05. The reproducibility of measurements was assessed by intraclass correlation coefficient (ICC).ResultsAfter four months of canine retraction, HMS and TMS from both laser and control sides showed significant three-dimensional displacement at p < 0.05. No significant difference in mean displacement in the vertical, sagittal, nor transverse planes between both sides was elicited.ConclusionLLL application in the used protocol does not affect the amount of miniscrew displacement in any of the three planes of space. Miniscrew displacement was significant in both groups.

Friction versus frictionless mechanics during maxillary en-masse retraction in adult patients with Class I bimaxillary dentoalveolar protrusion: a randomized clinical trial.

Extraction space closure is a challenging phase during orthodontic treatment that affects not only the total treatment duration but also the whole treatment outcome. To compare the efficiency of friction and frictionless mechanics during en-masse retraction of maxillary anterior teeth in adult patients with bimaxillary dentoalveolar protrusion. Two-arm parallel group, single-center randomized clinical trial. Thirty-two adult patients with bimaxillary protrusion were recruited and randomly allocated to two different retraction mechanics. A friction group, using NiTi coil springs and a frictionless group using closing T-loops for en-masse retraction. Randomization in a 1:1 ratio was generated by Microsoft Excel. The randomization numbers were secured in opaque sealed envelopes for allocation concealment. Retraction started in all patients following first premolars extraction using miniscrews as a source of indirect anchorage. Activation was done on a monthly basis until complete retraction of anterior segment. The rate of retraction, amount of anchorage loss, the dental, and soft tissue changes were analyzed on digital models and lateral cephalograms taken before retraction and after space closure. The outcome assessor was blinded through data concealment during assessment. Two patients were lost to follow up, so 30 patients completed the trial. The rate of anterior segment retraction was 0.88 ± 0.66mm/month in the frictionless group compared to 0.72 ± 0.36mm/month in the friction group which was statistically significant. Anchorage loss of 1.18 ± 0.72mm in the friction group compared to 1.29 ± 0.55 mm in the frictionless group with no significant difference. Comparable dental and soft tissue changes following en-masse retraction were reported in both groups, with no statistically significant difference. one patient complained of soft tissue swelling following miniscrew insertion, but the swelling disappeared after one week of using mouth wash. The study focused only on the maxillary arch. Both mechanics have successfully achieved the required treatment objectives in patients with bimaxillary dentoalveolar protrusion. Frictionless group showed a faster rate of retraction than the friction group, which was statistically but not clinically significant. Clinicaltrials.gov with the identifier NCT03261024.

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

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. 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. 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. 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.

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.

This invitro 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. 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. 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). Motor-driven OM insertion results in superior BMC and reduction in the number of CM, which may lead to better miniscrew stability.

Homemade CAD-CAM surgical guide for palatal mini-screw insertion for maxillary molar distalization providing anchorage. A two times original protocol

Temporary Anchorage Devices have revolutionized our approach to anchorage management. However, their placement may carry risks, such as root perforation, damage to the periodontal ligament, buccal-nasal communication, etc. The aim of this article is to describe an original protocol in two times for the placement of a palatal mini-screw through guided surgery using a guide created by Computer-Aided Design and Manufacturing (CAD/CAM) followed by the transfer of placement information to the laboratory for the fabrication of a Custom Medical Device (CMD) for distalization. A two-stage protocol is described and illustrated step by step. Phase 1 comprises 7 steps (including superimposition of maxillary cast and profile teleradiography, surgical tray design), followed by phase 2, which involves 3 final steps (including production of impression for laboratory, production of laboratory model with transfer of mini-screw position). Although the position of the mini screws remains precise, a discrepancy between the planning and the intraoral situation exists. The addition of a second step therefore enables the distalization appliance to be fitted precisely and without pitfalls. Finally, this protocol ensures safe placement, making work easier for the practitioner and, ultimately, for the patient. In a two-stage process, the placement of palatal mini screws through guided surgery using a guide created by CAD/CAM followed by the transfer of this information to the laboratory for the fabrication of a CMD for distalization proves to be a relevant approach.

Morphological evaluation of the nasopalatine canal using cone beam computed tomography and its clinical implications for orthodontic miniscrew insertion.

The morphology of the nasopalatine canal is crucial in the planning of prosthetic restorations in the anterior region of the maxilla, as well as in the placement of orthodontic mini-implants. The aim of this study was to assess the morphology of the nasopalatine canal using cone beam computed tomography (CBCT) scans of patients from the University Dental Clinic in Krakow, Poland, to define the position of the canal in relation to common sites of palatal median microimplant placement, and to investigate potential correlations between the anatomy of the canal and age and gender of the patients. A total of 120 CBCT images were used to assess the anatomy of the nasopalatine canal in 3 planes of space. The bone thickness anterior to the nasopalatine canal and the distance between the distal margin of Stenson's foramen and the predicted midpalatal microimplant position were also measured. The most frequently observed canal type in the coronal plane was the Y-shaped canal, which was present in 60.8% of patients. The nasopalatine canal was classified as cone-shaped in 31.7% of the scans, cylindrical in 28.3%, hourglass-shaped in 27.5%, and banana-shaped in 12.5%. The mean length of the nasopalatine canal was 11.58 mm. The mean width of the canal was 2.89 mm at the nasal fossa level, 1.94 mm in the middle, and 5.09 mm at the palatal level. The mean bone thickness anterior to the nasopalatine canal was 9.07 mm at the level of the nasal opening, 6.84 mm at the level of the oral opening, and 7.32 mm in the middle. The mean distance between the distal margin of Stenson's foramen and the predicted midpalatal microimplant position varied from 0 to 11.94 mm, with a mean of 2.49 mm. Given the variety of nasopalatine canal forms and dimensions, detailed analysis of CBCT scans is essential prior to the placement of implants and microimplants.

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

ObjectivesThe 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). MethodsTwenty-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. ResultsThe 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. ConclusionsPalatal 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 significanceAlthough 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.

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.

Anatomical Bone Characteristics of the Buccal Step Insertion Site for Mini-Screw Placement in Orthodontic Treatment: A CBCT Study

Background: To analyze the anatomical characteristics of a posterior area in the mandible localized distally to the second molars and extending in the vestibular direction toward the bony step, which we define as “buccal step”, in a patient with different skeletal patterns for mini-screw insertion. Methods: The sample included 85 CBCT (cone beam computed tomography) records selected from the digital archive. Analysis focused on the buccal step area. Sections were obtained in axial view using reference lines, and measurements of cortical and total bone were taken at specific points M0 (starting point, 6 mm apical from CEJc—cementoenamel junction crest), M2 (located 2 mm posterior to M0 in the apical direction), and M4 (positioned 4 mm posterior to M0 in the apical direction) in both directions. Six measurements were recorded for each scan root plane, assessing cortical and total bone depth. Results: The thickness of the bone increases toward the inside of the mouth at all tested sites (M0, M2, M4), which is good for placing mini-screws. Cortical bone thickness decreases toward the inside of the mouth, with no significant differences among the sites except for M0 vs. M4. People with a particular jaw shape (hypo-divergent) have a thicker cortical bone, indicating that facial structure affects bone thickness. Conclusions: The posterior buccal step insertion site has biomechanical advantages and reduces the risk of damaging roots during mini-screw insertions.

Midpalatal miniscrew insertion: The accuracy of digital planning and surgical placement

The objective of this study was to investigate the accuracy of palatal miniscrew insertion, evaluating the effect of guide fabrication and surgical placement. Guided insertion of bilateral paramedian palatal miniscrews was undertaken using Appliance Designer software (3Shape, Copenhagen, Denmark). A resin surgical guide (PPro Surgical Guide; Straumann AG, Basel, Switzerland) was used. Superimposition of the miniscrew position relative to the digital design was undertaken using bespoke software (Inspect 3D module, OnyxCeph; Image Instruments GmbH, Chemnitz, Germany) to assess surgical inaccuracy. Miniscrew position relative to the surgical guide was also assessed to isolate the effect of planning inaccuracies. Both horizontal and vertical discrepancies were evaluated at both implant locations. Twenty-seven patients having bilateral palatal insertions were examined. Mean discrepancies were<0.5 mm, both in the horizontal and vertical planes. The mean overall horizontal and vertical discrepancy between the digital design and final miniscrew position on the left side was 0.32 ± 0.15 mm and 0.34 ± 0.17 mm, respectively. The maximum horizontal discrepancy observed was 0.72 mm. No significant differences were observed in relation to the accuracy of mini-implant positioning on the basis of sidedness, either for horizontal (P= 0.29) or vertical (P= 0.86) discrepancy. High levels of accuracy associated with guided insertion of paramedian palatal implants were recorded with mean discrepancies of less than 0.5 mm both in the horizontal and vertical planes. No difference in accuracy was noted between the left and right sides. Very minor levels of inaccuracy associated both with surgical techniques and surgical guide fabrication were recorded.

Accuracy of the infrazygomatic orthodontic bone screws digital planning and surgical guided positioning: A observational study

Objectives: The objective of the study was to evaluate the accuracy of surgical guidance for the insertion of infrazygomatic (IFZ) miniscrews by means of a cone beam computed tomography (CBCT) evaluation. Material and Methods: Nine patients (five men and four women, from 14.8 to 41.4 years of age) were recruited for the study. Rhinoceros software was used to digitally plan the infrazygomatic miniscrew insertion with the INFRABSTEER method (INFRA-zygomatic and Buccal Shelf method), superimposing intraoral scans and a CBCT obtained at T0. No orthodontic movement was performed, and six months later a second CBCT was done (T1). Rhinoceros software was used to superimpose T0 and T1 files. Mesio-distal, bucco-palatal, and vertical linear discrepancy in cap and tip and an angular discrepancy between the mini-screws was measured. To check the repeatability of the measurements, the intraclass coefficient (ICC) was calculated. The significance level considered is P &lt; 0.05. The ICCs are all &gt;0.85 and significantly different from 0 (P &lt; 0.05), indicating excellent repeatability of measurements. Results: The lowest mean linear distance was found to be the mesio-distal distance at the tip with 0.23 ± 0.241 mm. All linear distances produced an average distance of less than 0.5 mm, except for the bucco-palatal distance measured at the tip. The smallest angular measurement was obtained from the intersection of the axes of the miniscrews in the mesio-distal plane (1.58° ± 1.458°). Conclusion: The combination of a digitally planned and a template-guided surgical positioning procedure allows excellent control of infrazygomatic miniscrews insertion.

Reliability and safety of miniscrew insertion planning with the use of lateral cephalograms assessed on corresponding cone-beam computer tomography images.

Recently, lateral cephalograms have been proposed for guided miniscrew insertion planning. Therefore, the aim was to assess the reliability and safety of such planning on corresponding cone-beam computer tomography (CBCT) images. Intraoral scans, lateral cephalograms, and CBCT images of 52 subjects (even sexes distribution), aged 15.1 ± 2.5 years, were included. Miniscrew (n = 104) insertion planning was performed using lateral cephalograms superimposed on the maxillary intraoral scans, while the assessment of their bicortical placement, length in bone, contact with adjacent teeth, incisive canal, and nasal floor perforation was done on corresponding superimposed CBCT images. Moreover, maxillary incisor inclination, crowding, and the maxillary intercanine width were measured. The overall miniscrew length in bone was 7.2 ± 1.3mm. Bicortical placement was seen in 58.7% of the sample (38.5% of subjects). Incisive canal and nasal floor perforation was seen in 25% and 21.2% of subjects, respectively. No contact of the miniscrew with adjacent teeth was recorded. A negative significant interaction was seen between the miniscrew length in bone, the percentage of total miniscrew length and maxillary anterior teeth crowding (β, -0.10, P = .047 and β, -0.90, P = .006, respectively). Moreover, a positive significant interaction was seen between the incisive canal perforation and maxillary anterior teeth crowding (OR = 1.32, P = .021). Exclusion of subjects with impacted teeth. Miniscrew insertion planning using lateral cephalograms, despite being safe in preventing contact with adjacent teeth, is limited in achieving bicortical placement and insufficient in completely avoiding incisive canal and nasal floor perforation.

An evaluation of bone depth at different three-dimensional paths in infrazygomatic crest region for miniscrew insertion: A cone beam computed tomography study

ObjectiveTo investigate the difference and distribution of bone depth at different three-dimensional simulated paths to help optimize the insertion path for miniscrew placement in the infrazygomatic crest. MethodsCone beam computed tomography scans of 80 adults (38 males and 42 females; mean age, 27.0 years) were assessed. For each subject, bone depth of 81 simulated insertion paths at different insertion points and three-dimensional angulations was measured in 160 infrazygomatic crests; the differences were evaluated using the adjusted Friedman test. The bone deficiency ratio for each path was calculated. Distributions of measurements were analyzed and reported as specially designed colormaps. ResultsBone depth increased, and bone deficiency ratio reduced mesially to distally (P < 0.001), apically to coronally (P < 0.01), and at a greater gingival and distal inclination (P < 0.05). The maximum bone depth (10.72 mm) was observed 13 mm above the maxillary occlusal plane in the mesiobuccal root of the maxillary second molar. The minimum bone depth (3.4 mm) was observed 17 mm above the maxillary occlusal plane in the distobuccal root of the maxillary first molar. No bone deficiency was detected at the paths of 13 mm above the maxillary occlusal plane at a gingival inclination of 70° and distal inclination of 30° in the mesiobuccal root of the maxillary second molar. The highest bone deficiency ratio is present 17 mm above the maxillary occlusal plane at a gingival inclination of 60° and a distal inclination of 0° in the distobuccal root of the maxillary first molar (89/160). ConclusionInsertion paths located at 13 mm above the maxillary occlusal plane in the mesiobuccal root of the maxillary second molar were optimal. A gingival inclination of 70° and a distal inclination of 30° could be beneficial. The distobuccal root of the maxillary first molar region or above the 17 mm insertion plane may not be recommended.

Quantitative Measurement of Buccal Cortical Bone Thickness in Infrazygomatic Crest Area at Different Alveolar Bone Heights and Insertion Angles of Infrazygomatic Crest Screws: A CBCT Study

Introduction Skeletal anchorage devices for the efficient orthodontic treatment mechanics can be placed at various interradicular and extraradicular sites intra orally. However, their placement in the infrazygomatic crest area can broaden the horizon of orthodontic treatment. The bone thickness in the infrazygomatic crest (IZC) area can vary at different heights and insertion angles during the placement of IZC screws between maxillary second premolar and second molar region. Aims and objectives The purpose of our study was to evaluate the variation in bone thickness in the IZC area at different insertion angles along the mesiobuccal root of maxillary first molar and at different heights from the crest of the alveolar bone in the apical direction between maxillary second premolar and second molar region using cone beam computed tomography, so as to determine the best possible site where the bone thickness will be maximum that will suit to a particular size of IZC screw. Materials and Methods CBCT images of 50 subjects were analyzed by a single observer, the bone thickness in the IZC area was measured and interpreted at different heights from the alveolar crest in the apical direction, that is, 5 mm, 7 mm, 9 mm, 11 mm at six regions between maxillary second premolar and second molar. Bone thickness was also measured at different insertion angles ranging from 55º to 75º to occlusal plane of permanent maxillary first molar along its mesiobuccal root. Results The bone thickness in the IZC area was 4.5 mm–3.5 mm, when it was measured at different angles ranging from 55º to 75º to the occlusal plane of maxillary first molar along its mesiobuccal root with maximum bone thickness at 75° with a mean ± SD of 4.56 ± 1.4. Statistically significant differences in bone thickness were found between maxillary first and second molar on both right and left sides at different heights with maximum bone thickness at 11 mm apical from the alveolar crest with a mean ± SD of 2.03 ± 0.76 and 1.91 ± 0.88, respectively, and along the mesial root of maxillary second molar on right and left sides at 11 mm apical from the alveolar crest with a mean ± SD of 2.12 ± 0.80 and 1.95 ± 0.75, respectively. Conclusions The best site and safe zone for miniscrew insertion in IZC area is at 7 mm to 9 mm distance from the alveolar crest apically along the mesial root of maxillary second molar and at an angle of 55°–75º to the occlusal plane of maxillary first molar, so as to ensure the adequate stability of the miniscrew and without causing any damage to the adjacent anatomical structures.

Stability of miniscrews depending on the anatomical and topographic zone of localization during orthodontic treatment

During orthodontic treatment, miniscrews are used as additional hardware to create skeletal support for more efficient movement of teeth on braces and aligners. The most common areas for placing miniscrews are the alveolar ridge of the upper jaw, the retromolar region, the interradicular space, and the subzygomatic ridge. Purpose of the study: to evaluate the influence of the anatomical and topographic localization of steel and titanium miniscrews on their stability in bone tissue during orthodontic treatment using fixed orthodontic appliances Materials and methods. An examination, photo proto-col, and analysis of cone beam computed tomography (CBCT) were performed in 60 patients who had a history of having a miniscrew placed in the interradicular and retromolar areas, and the subzygomatic ridge. An analysis of the stability of miniscrews was carried out immediately after the operation of installing a miniscrew, performed under local anesthesia, and during the entire period of orthodontic treatment with fixed appliances. Results.The most common primary and secondary rejection of titanium miniscrews was observed in the retromolar re-gion (6.2 and 18.7%, respectively), steel ones — in the subzygomatic ridge (50 and 37.5%, respectively). Con­clusion: The maximum stability of miniscrews when treating patients with a fixed technique using a ske-letal support is observed in the interroot region. It is necessary to carefully plan the site of miniscrew insertion based on CBCT data, taking into account the individual characteristics of the bone tissue structure to reduce the risk of loss of skeletal support