Orthodontic Miniscrew Placement Research Articles

Should Cone-Beam Computed Tomography Be Performed Prior to Orthodontic Miniscrew Placement in the Infrazygomatic Crest Area?-A Systematic Review.

There is no unequivocal scientific consensus for the temporary anchorage device (TAD) positioning in the infrazygomatic crest area (IZC). The two principal aims of this systematic review were to assess bone availability in the IZC and to establish both the target site and the need for cone-beam computed tomography (CBCT) prior to miniscrew placement. The study was performed following PRISMA guidelines (PROSPERO: CRD42023411650). The inclusion criteria were: at least 10 patients, three-dimensional radiological examination, and IZC assessment for the TAD placement. ROBINS-I tool and Newcastle-Ottawa Scale were used for quality evaluation. No funding was obtained. The study was based on the information coming from: PubMed, Google Scholar, Web of Science Core Collection, MDPI, Wiley, and Cochrane Libraries. The last search was carried out on 1 August 2023. Fourteen studies were identified for analysis. A narrative synthesis was performed to synthesize the findings of the different studies. Unfortunately, it is not possible to establish the generally recommended target site for IZC TAD placement. The reasons for this are the following: heterogeneity of available studies, inconsistent results, and significant risk of bias. The high variability of bone measurements and the lack of reliable predictors of bone availability justify the use of CBCT for TAD trajectory planning. There is a need for more high-quality studies aiming three-dimensional bone analysis of the IZC.

Effects of an augmented reality aided system on the placement precision of orthodontic miniscrews: A pilot study

Background/purposeAugmented reality (AR) is gaining popularity in medical applications, which may aid clinicians in achieving improved clinical outcomes. The purpose of this study was to determine the positional and angle errors of orthodontic miniscrew placement by using a self-developed AR aided system. Materials and methodsCone beam computed tomography (CBCT) and patient printed models were used in in vitro experiments. The participants were divided into a control group and an AR group, in which traditional orthodontic methods and the AR-aided system were used respectively. After the information obtained from the CBCT images and navigation system was combined on the display device, the AR-aided system indicated the planned miniscrew position to guide the clinicians during the placement of miniscrews. Both methods were compared by a senior and a junior dentist, and the position and angle of miniscrew placement were statistically analyzed using Wilcoxon's signed-rank and Mann–Whitney U tests. ResultsWhen the AR-aided system was used, the accuracy of miniscrew placement in the mesiodistal position considerably increased (83%) when the procedure was performed by a senior clinician. In addition, the accuracy of miniscrew placement in the mesiodistal position and the angle of miniscrew placement considerably increased by approximately 67% and 72%, respectively, when the procedure was performed by a junior clinician. The position error of miniscrew placement was smaller for the junior clinician when the AR-aided system was used than for the senior clinician. ConclusionThe AR-aided system improved the accuracy of miniscrew placement regardless of the clinician's level of experience.

Finite Element Analysis of Maxillary Teeth Movement with Time during En Masse Retraction Using Orthodontic Mini-Screw

Introduction: The aim of this study was to determine the placement of an orthodontic mini-screw (OMS) and the length of an anterior retraction hook (ARH) with en masse retraction. Continuous maxillary tooth movement pattern was simulated by finite element analysis (FEA). Materials and methods: Extraction of the first premolar was hypothesized with a finite element model. The placement of OMS was analyzed for the following two groups: (1) a high OMS (HOMS) group with OMS placed horizontally at the mesial side of the second premolar and apically 10 mm above the arch wire, and (2) a low OMS (LOMS) group with OMS placed horizontally between the second premolar and the first molar and apically 8 mm above the arch wire. According to the height of ARH, each group was divided into three subgroups. Results: When the extraction space of the first premolar was closed, anterior teeth were intruded in the HOMS group but extruded in the LOMS group. In all cases, the first molar was intruded. According to the intrusion of the first molar and extrusion of anterior teeth, the occlusal plane rotated clockwise (CW) in the LOMS group. However, in the HOMS1 group, the occlusal plane rotated counterclockwise (CCW) due to more intrusion of anterior teeth than that of the first molar. Conclusion: By analyzing six cases of different OMS and ARH, changes of incisor and molar in en masse retraction with the extraction of the first premolar could be predicted. In addition, OMS placement and ARH length can be determined based on results of incisal showing. This study can also help esthetic orthodontic results.

Evaluation of palatal bone depth, cortical bone, and mucosa thickness for optimal orthodontic miniscrew placement performed according to the third palatal ruga clinical reference.

This retrospective CBCT study aimed to evaluate the palatal anatomical characteristics using the third palatal ruga as a reliable clinical reference for miniscrew placement. Thirty-six subjects (mean age17.1 y.o. ± 4.1) were randomly selected and their records (CBCT volume and maxillary digital models) were included.BlueSkyPlan CBCT software viewer (BluSkyBio, V4.7) was used to measure the following outcomes at the level of third palatal ruga, 2 mm anteriorly and 2 mm posteriorly: total bone depth, cortical bone thickness, and mucosa thickness. The outcomes were evaluated on lines perpendicular to the palatal mucosa laying on different sagittal planes: the mid-palatal plane, 2 and 4 mm paramedian planes. The maximum mean amount of bone depth was registered 2 mm posteriorly to the third ruga and 4 mm paramedian (9.7 mm). No significant difference was observed between the third ruga insertion site and its corresponding 2 mm posterior site. Cortical bone of palatal vault did not change significantly in anteroposterior direction for all the considered sites. Significant differences were found comparing cortical bone at the suture level with cortical bone 2-mm and 4-mm paramedian at all anteroposterior levels. Palatal mucosa increases its thickness in paramedian insertion sites, and it decreases in posterior insertion sites. Both third palatal ruga and 2 mm posteriorly to third ruga (4 mm paramedian) could be the optimal insertion site for palatal miniscrew placement, depending on individual anatomic conditions. The thickness of the cortical palatal bone showed, at 4 mm paramedian, optimal characteristics for miniscrew primary stability. Palatal mucosa thickness values suggest miniscrew neck extension of 2.0-2.5 mm for optimal mucosa adaptation.

Bacteremia after Orthodontic Miniscrew Insertion.

Objectives: Use of miniscrews has become very common in orthodontic treatment of patients. Following tissue manipulation during miniscrew placement, bacteremia may occur, which is important in patients susceptible to infective endocarditis. This study aimed to investigate the possibility of bacteremia following orthodontic miniscrew placement. Materials and Methods: The present quasi-experimental study was conducted on 30 orthodontic patients, including 11 males (36.7%) and 19 females (63.3%) with a mean age of 23.67±4.87 years, who required miniscrew placement in their treatment plan. Two blood samples were taken from the patients for aerobic and anaerobic cultures right before and 30-60 seconds after miniscrew placement. To investigate the presence of bacteremia, the blood samples were incubated in an automated blood culture machine for five days. The standard biological methods were used for the positive sample(s) to identify the type of bacteria. Data analysis was performed using the McNemar test. Results: The blood samples of 29 patients were negative for the bacteria before and after miniscrew placement. Blood sample of one patient was positive for aerobic and anaerobic bacteria after miniscrew placement. However, bacteremia was negative in the initial (preplacement) blood samples for both aerobes and anaerobes. Conclusion: Miniscrew placement in orthodontic patients was not associated with bacteremia.

Comparison between Topical and Injection Anesthetics on Pain Related to Orthodontic Miniscrew Placement: A Split-mouth Study

The aims of this study were to compare the anesthetic effect of a lidocaine/prilocaine (L/P) topical anesthetic with placebo on pain from needle sticks and to compare the anesthetic effect of the L/P topical anesthetic with an infiltrative anesthetic on pain from orthodontic miniscrew placement. Pain elimination was analyzed from two interventions: (a) needle stick and (b) miniscrew insertion. When assessing pain from needle stick, one side of the mandible received 2.5% lidocaine/2.5% prilocaine topical anesthetic, and the other side received placebo. When evaluating pain from miniscrew placement, one side of the mandible received L/P topical anesthetic and the other side received infiltrative anesthetic. The findings were recorded on a Visual Analogue Scale after needle stick and after miniscrew placement. Subjective assessment was analyzed by a questionnaire. The L/P topical anesthetic significantly eliminated the pain from needle stick (Mann-Whitney test of medians, 29.0 vs 0.0, respectively, p<0.001). However, the injection anesthetic eliminated the pain from the miniscrew placement better than the L/P topical anesthetic (Mann-Whitney test of medians, 0.0 vs 5.5, respectively, p<0.001). Eighty percent of the subjects felt more comfortable with L/P topical anesthetic than injection anesthetic. Pain from needle stick pain was reported to be the most uncomfortable part of the study. The L/P topical anesthetic efficiently eliminated pain from needle stick. The L/P topical anesthetic did not completely eliminate pain from miniscrew placement as the injection anesthesia, but it did reduce pain to tolerable levels. L/P topical anesthetics can significantly eliminate pain from needle stick injections, and L/P topical anesthetics can reduce pain from orthodontic miniscrew placement to tolerable levels.

Improving Oral Surgery: A Workflow Proposal to Create Custom 3D Templates for Surgical Procedures

Background: Computer-guided technologies are adopted in various fields of surgery to limit invasiveness and obtain patient benefits in terms of surgery duration and post-operative course. Surgical templates realized through CAD/CAM technologies are widely diffused in implant dentistry. The aim of this work is to propose, beyond implantology, the feasibility of application of 3D printed surgical templates in oral surgery procedures requiring osteotomies (like maxillary cyst enucleation and tooth disimpaction) in order to obtain accurate surgeries, avoid anatomical damage of surrounding structures and decrease patient’s morbidity, using a simple, low-cost protocol of fabrication. Objective: To provide a reliable CAD-CAM workflow for the realization of surgical templates in oral surgery. Methods: Three clinical scenarios are described: A maxillary canine disimpaction, a mandibular cyst removal, and an orthodontic miniscrew placement. Each one was managed using custom surgical templates realized using the proposed workflow. A Stereolithography (STL) file of maxillary structures was obtained by the use of a 3D medical image processing software (Materialise Mimics 20.0) a segmentation toolbox acquiring RX volumes by Cone-Beam Computed Tomography (CBCT). Digital models of the teeth, acquired as STL files directly, are imported in the same 3D medical image processing freeware (Materialise Mimics 20.0) to merge STL files of maxillary structures and teeth. Data are transported into Blue Sky Plan 4.0 (Blue Sky Bio, LLC), a software for 3D implant guides fabrication, together with the DICOM images package of maxillary volumes to carry out the pre-surgical treatment planning. Anatomical structures at risk are identified; a contour of ideal incision shape and bone osteotomy extent is drawn. Finally, the resulting three-dimensional guide is digitally generated and the surgical guide printed. The resulting 3D template shows the following major features: teeth support, flap management and bone osteotomy design. Results: The proposed work-flow aided the surgeon in both pre-operative and intra-operative work phases through accurate virtual planning and the fabrication of precise surgical guides to be used in oral surgery practice. In each clinical scenario, the use of custom 3D templates allowed better control of the osteotomy planes and flap management. No adverse events occurred during both surgical and healing phases. Conclusion: The proposed digital workflow represents a reliable and straightforward way to produce a surgical guide for oral surgery procedures. These templates represent a versatile tool in maxillary cyst enucleations, tooth disimpaction, and other surgical procedures, increasing accuracy, minimizing surgical complications, and decreasing patient’s morbidity.

Safe zones of the maxillary alveolar bone in Down syndrome for orthodontic miniscrew placement assessed with cone-beam computed tomography

The aim of this study was to quantify the available maxillary alveolar bone in a group of individuals with Down syndrome (DS) to determine the best areas for orthodontic miniscrew placement. The study group consisted of 40 patients with DS aged 12–30 years. We also selected an age and sex-matched control group. All measurements were performed on cross-sectional images obtained with cone-beam computed tomography. The selected areas of interest were the 4 interradicular spaces between the distal wall of the canine and the mesial wall of the second molar, in both maxillary quadrants. We measured the vestibular-palatine (VP) and mesiodistal (MD) dimensions to depths of 3, 6 and 9 mm from the alveolar ridge. We also measured the bone density in the same interradicular spaces of interest to 6 mm of depth from the alveolar crest. VP measurements were longer in the more posterior sectors and as the distance from the alveolar ridge increased. MD measurements also increased progressively as the distance from the alveolar ridge increased. In general, both the VP and MD measurements in the DS group were similar among the male and female participants. As age increased, the MD distance increased, while the VP distance decreased. The VP distance was ≥6 mm in at least 75% of the DS group in practically all assessed interdental spaces. The MD distance was ≥2 mm in at least 75% of the DS group only between the first and second molar, to 9 mm of depth from the alveolar ridge. The safe area for inserting orthodontic miniscrews in DS patients is restricted to the most posterior and deepest area of the maxillary alveolar bone.

Endodontic and Surgical Management of Iatrogenic Root Injury Caused by Orthodontic Miniscrew Placement: A Case Report.

One of the potential serious complications, associated with the inter-radicular placement of an orthodontic miniscrew, is root injury. This article reports the endodontic and surgical treatments of an iatrogenic root perforation in a mandibular first molar caused by the placement of an orthodontic miniscrew anchorage. The 24-month follow-up showed a successful treatment outcome.

Buccal cortical bone thickness in different sagittal skeletal relationship

PurposeTo assess buccal cortical bone thickness of the alveolar process in the maxilla and mandible in subjects with different skeletal relationship as an aid in orthodontic miniscrew placement. Materials and methodsThe study was carried out using cone-beam computed tomography (CBCT) images of 94 adult subjects with skeletal Class I, II or III sagittal relationship and normal mandibular plane angle. Buccal cortical bone thickness was obtained at the alveolar processes from canine to second molar at 2 different vertical levels (6, and 8mm) from the cementoenamel junction (CEJ). Analysis of variance (ANOVA) was used to analyse differences in cortical bone thickness. ResultsThe difference in mean values of buccal Cortical thickness was significant between the three skeletal classes in both arches and all sites except for the site between first and second mandibular molars (P<0.05). In the mandible, buccal cortical plate was thickest between first and second molar in all skeletal classes. In the maxilla, the highest cortical bone thickness for Class I subjects was between first and second molar, for Class II subjects was between canine and first premolar, and for Class III subjects was between first and second premolar. Mandibular measurements increase apically and posteriorly in all skeletal classes. ConclusionsBuccal cortical bone thickness could be influenced by skeletal relationship. The mandible shows a similar pattern for all skeletal classes. In the maxilla each skeletal relationship shows a different pattern. Skeletal relationship need to be considered in site choice for miniscrew placement.

Insertion torque and Periotest values are important factors predicting outcome after orthodontic miniscrew placement.

Approximately 14% of orthodontic anchor screws (miniscrews) become dislodged regardless of the accuracy of placement. It is therefore important to investigate the factors causing dislodgement. We evaluated the stability of miniscrews after placement to identify factors influencing outcome in orthodontic treatment using miniscrews. We investigated 120 miniscrews (Dual-top Auto Screw III; Jeil Medical, Seoul, Korea) (diameter, 1.4mm; length, 6mm) placed on the buccal or lingual side between the maxillary second premolar and the first molar in women. Patient age and rate and time of screw dislodgement were examined. Insertion torque values and Periotest (Tokyo Dental Industrial, Tokyo, Japan) measurements indicating horizontal and vertical mobility of the inserted screws were compared between groups with and without dislodgement (failure and success groups, respectively). Mean insertion torque values were 10.7±1.9N·cm and 8.5±2.1N·cm in the failure and success groups, respectively. Cortical bone thickness measurements (success group, 1.34±0.35mm; failure group, 0.99±0.09mm) were significantly higher, whereas Periotest values at placement (success group, horizontal, 4.9±1.4; vertical, 4.7±1.3; failure group, horizontal, 7.0±0.8; vertical, 7.1±0.9) were significantly lower in the success group than in the failure group. The Periotest value, together with insertion torque and cortical bone thickness, could serve as an index of initial stability for predicting the outcome of miniscrew placement.

Buccal Cortical Bone Thickness in Iraqi Arab Adults by Cone Beam Computed Tomography for Orthodontic Mini-Implants

Background: Cortical bone thickness is important for the stability of mini implants. Placing mini implants in sites of favorable cortical bone thickness would guarantee better initial stability and long-term success. The aim of this study was to investigate gender, side and jaw differences of the buccal cortical bone thickness as a guide for orthodontic mini screw placement. Materials and Methods: The sample was selected from the patients attending the Specialized Health Center in Al-Sadr City / 3D department. Thirty patients (15 males and 15 females) were selected and cone beam computerized tomographic images were done. Then the buccal cortical bone thickness was measured at thirteen inter radicular sites in the maxilla and mandible from the mesial side of the second molar to the mesial side of the second molar on the other side. The resulting data were statistically analyzed using independent t-test on SPSS program. Results: The buccal cortical bone thickness of the males was more than the females for both jaws. The mandibular buccal cortical bone thickness was thicker than in the maxillary and in the anterior region was thinner than in the posterior region for each jaw. The thickness of the buccal cortical bone was generally greater on the left side

Determination of soft tissue thickness at orthodontic miniscrew placement sites using ultrasonography for customizing screw selection.

A wide variety of factors affect the success of orthodontic miniscrews in clinical situations, including thickness of the soft tissues. Our objectives were to assess area-related and sex-related differences in the soft tissue thicknesses of the buccal attached gingiva of the maxilla and the mandible, and the palatal masticatory mucosa at common orthodontic miniscrew placement sites, and to prescribe a guideline for miniscrew selection for a predictable clinical outcome. The sample consisted of 32 randomly selected adults in the age group of 20 to 25years. Soft-tissue thickness of the concerned areas was measured intraorally using an A-mode ultrasound transducer probe (Biomedix Optotechnik & Devices, Bangalore, India). Independent t tests, paired t tests, and 1-way analysis of variance with Duncan post hoc tests were used for statistical analysis. The palatal masticatory mucosa was 2 to 3 times thicker than the corresponding buccal attached gingiva in both sexes. The thickness of the palatal masticatory mucosa in the midpalatal region was consistently less than 1mm (range, 0.7-1mm). The buccal attached gingiva was comparatively thicker in the maxilla than in the mandible, except for the mandibular molar regions. It also was found that the buccal attached gingiva was thicker in women in the maxillary anterior regions, whereas, the thickness was greater in the maxillary posterior regions in the men. Evaluating the soft tissue thicknesses before selecting an orthodontic miniscrew can help in providing a definite guide for orthodontists to select an appropriate screw in everyday clinical practice, further enhancing the predictability of miniscrew-assisted orthodontics.

Effects of orthodontic miniscrew placement angle and structure on the stress distribution at the bone miniscrew interface – A 3D finite element analysis

The study was conducted to evaluate the effects of orthodontic miniscrew placement angle and structure in terms of length and diameter on stress distribution at the bone miniscrew interface. 10 FE models were created representing miniscrews inserted in the buccal alveolar bone between the maxillary first molar and second premolar to simulate varying angulations of miniscrew placement (90°, 60°, 45°, 30°) to the long axis of the maxillary first molar, varying length (6mm, 8mm, 10mm, 12mm) and varying diameter (1.2mm, 1.3mm, 1.4mm, 1.5mm). In order to simulate retraction forces an identical force of 200 g was applied perpendicular to the long axis of the miniscrew in all the models. Finite Element Modeling Analysis was used to analyze the stress distribution at the bone miniscrew interface. Minimum and maximum stress in the miniscrew was generated at placement angles of 30° and 90° respectively. In the bone minimum and maximum stress was found at placement angles of 90° and 30° respectively. On increasing the miniscrew diameter stress in both the miniscrew and the bone decreased. There was no difference found in the stress distribution patterns with varying miniscrew length. Based on stress patterns, biomechanical stability of the miniscrew is enhanced by a placement angle of 90° to the long axis of the first maxillary molar and a diameter of 1.5 mm for the site selected in this study while miniscrew length has no implication on its stability.

Endodontic and Surgical Treatment of Root Damage Caused by Orthodontic Miniscrew Placement

IntroductionMiniscrews are being increasingly used for anchorage control in orthodontics. Despite the concern over root damage caused by miniscrews, there are few reports of precise clinical evaluations and appropriate management of that damage. In the case presented herein, the root damage caused by the placement of miniscrews was repaired by root canal treatment and surgical intervention. MethodsA 44-year-old man received orthodontic treatment for intrusion of the left maxillary first molar with a miniscrew anchorage system. During that treatment, the miniscrews had fallen out and had to be reinserted more than 6 times in the same area. Two years later, the patient complained of a spontaneous pain in the maxillary left molar region. Although the patient received root canal treatment, intraoral sinus tracts could still be detected, and the patient's discomfort persisted. Periradicular surgery revealed that the persistent infection was related to root surface damage caused by orthodontic miniscrew placement. Healing was achieved by a combination of root canal treatment and surgical intervention. ResultsScanning electron microscopy of the damaged distobuccal root apex revealed a mature biofilm consisting of a network of matrix that contained mostly rod-like and spherical bacteria. At a 12-month recall checkup, the patient was free of pain. A repeat periapical radiograph revealed reduction of the pretreatment radiolucent lesion. ConclusionsMore careful planning of miniscrew placement is necessary to lessen the danger of root damage. Furthermore, a precise evaluation of both root and pulpal damage and careful consideration of the choice of optimal treatment modality are needed.

Measurement of cortical bone thickness in adults by cone-beam computerized tomography for orthodontic miniscrews placement

The purpose of this study was to investigate the cortical bone thickness of the inter-dental area of both jaws for orthodontic miniscrew placement. The cone-beam computerized tomography images of 32 non-orthodontic adults with normal occlusion were taken to measure the cortical bone thickness in both jaws. One-way analysis of variance (ANOVA) was used to analyze the differences in cortical bone thickness. Buccal cortical bone in the mandible was thicker than that in the maxilla. In the maxilla, cortical bone thickness was thicker in the buccal side than in the palatal side. Buccal cortical bone thickness in the mandible was thickest at the site distal to the first molar, and in the maxilla it was thickest at the site mesial to the first molar, while in the palatal side of maxilla it was thickest at the site mesial to the second premolar. The changing pattern of cortical bone thickness varies at different sites. In the buccal side of maxilla, the thinnest cortical bone thickness was found to be at 4 mm level from the alveolar crest, while the thickest was at 10 mm level (except for the site mesial to the first premolar). The buccal cortical bone thickness at the sites mesial or distal to the first molar in the mandible and palatal cortical bone thickness of maxilla tended to increase with increasing distance from the alveolar bone.

Comparison of success rates of orthodontic mini-screws by the insertion method.

ObjectiveThe aim of this study was to compare the success rates of the manual and motor-driven mini-screw insertion methods according to age, gender, length of mini-screws, and insertion sites.MethodsWe retrospectively reviewed 429 orthodontic mini-screw placements in 286 patients (102 in men and 327 in women) between 2005 and 2010 at private practice. Age, gender, mini-screw length, and insertion site were cross-tabulated against the insertion methods. The Cochran-Mantel-Haenszel test was performed to compare the success rates of the 2 insertion methods.ResultsThe motor-driven method was used for 228 mini-screws and the manual method for the remaining 201 mini-screws. The success rates were similar in both men and women irrespective of the insertion method used. With respect to mini-screw length, no difference in success rates was found between motor and hand drivers for the 6-mm-long mini-screws (68.1% and 69.5% with the engine driver and hand driver, respectively). However, the 8-mm-long mini-screws exhibited significantly higher success rates (90.4%, p < 0.01) than did the 6-mm-long mini-screws when placed with the engine driver. The overall success rate was also significantly higher in the maxilla (p < 0.05) when the engine driver was used. Success rates were similar among all age groups regardless of the insertion method used.ConclusionsTaken together, the motor-driven insertion method can be helpful to get a higher success rate of orthodontic mini-screw placement.

Root canal treatment of a periradicular lesion caused by unintentional root damage after orthodontic miniscrew placement: a case report

To present the successful endodontic management of a maxillary lateral incisor tooth with a periradicular lesion caused by unintentional root damage after orthodontic miniscrew placement. A 22-year-old female was diagnosed with a skeletal Class II, Division 2 malocclusion with Class II molar and canine relationships on both sides. The treatment plan included distalization of the maxillary first molars bilaterally followed by full fixed appliance therapy. For the maxillary molar distalization, an appliance in conjunction with a miniscrew anchorage system was designed. Two months later, the patient came to the clinic with complaints of pain in the maxillary right lateral incisor region. On intraoral examination, intraoral sinus tracts were detected in the maxillary right buccal sulcus and palate. A large radiolucent lesion with a well-defined margin around the root of the maxillary right lateral incisor was seen. Root canal treatment was performed on the maxillary right lateral incisor tooth. The root canal was filled with gutta-percha and AH Plus sealer, using a lateral compaction technique. The final restoration of the tooth was completed using composite, and the tooth was reviewed after 10 months. The tooth was asymptomatic and radiographically showed repair of the lesion. Healing was achieved without any need for further endodontic or surgical intervention. Key learning points • This case illustrates the need to take care with miniscrews when performing orthodontic treatment, especially when the miniscrews are in close proximity to root apices. • The periradicular lesion as a result of miniscrew damage was successfully treated with root canal treatment.

Computed tomographic analysis of tooth-bearing alveolar bone for orthodontic miniscrew placement

When monocortical orthodontic miniscrews are placed in interdental alveolar bone, the safe position of the miniscrew tip should be ensured. This study was designed to quantify the periradicular space in the tooth-bearing area to provide practical guidelines for miniscrew placement. Computerized tomographs of 30 maxillae and mandibles were taken from nonorthodontic adults with normal occlusion. Both mesiodistal interradicular distance and bone thickness over the narrowest interradicular space (safety depth) were measured at 2, 4, 6, and 8 mm from the cementoenamel junction. Mesiodistal space greater than 3 mm was available at the 8-mm level in the maxillary anterior region, between the premolars, and between the second premolar and the first molar at 4 mm. In the mandible, sufficient mesiodistal space was found between the premolars, between the molars, and between the second premolar and the first molar at the 4-mm level. Safety depth greater than 4 mm was found in the maxillary and mandibular intermolar regions, and between the second premolar and the first molar in both arches. Subapical placement is advocated in the anterior segment. Premolar areas appear reliable in both arches. Angulated placement in the intermolar area is suggested to use the sufficient safety depth in this area.

Quantitative cone-beam computed tomography evaluation of palatal bone thickness for orthodontic miniscrew placement

The purpose of this study was to evaluate the 3-dimensional thickness of the palate to determine the best location to place miniscrews. We selected digital volumetric tomographs from 162 healthy subjects, aged 10 to 44 years (80 male, 82 female). The sample was divided into 3 groups. Group A included 52 subjects (ages, 10-15 years; 28 boys, 24 girls); group B included 38 subjects (ages, 15-20 years; 18 males, 20 females), and group C had 72 subjects (age, 20-44 years; 34 men, 38 women). Ninety-degree paracoronal views of the palatal region at 4, 8, 16, and 24 mm posterior to the incisive foramen were reconstructed, and bone height was measured laterally from the midline in each reconstruction at 0-, 3-, and 6-mm increments to describe the topography of the palate. Measurements of palatal height in 27 of the 162 patients were made by 2 different investigators. Method error was calculated according to the Dahlberg formula (S(2) = Sigmad(2)/2n), and systematic error was evaluated with the dependent Student t test, with P <0.05 considered significant. The thickest bone (4-8 mm) was found in the anterior part of the palate, at the suture and in the paramedian areas, but the posterior region, despite its reduced thickness, is also suitable for miniscrews. The Kruskal-Wallis test showed no significant differences between the groups in the various palatal sections (median suture, 3 and 6 mm to the right and left of the suture) except between groups A and C in the 16-mm paracoronal section at 6 mm to the right and left of the suture. There were no statistically significant differences due to sex or between the right and left sides of the palate. The anterior region is the thickest part of the palate, but the bone thickness in the posterior region is also suitable for screws of appropriate diameter and length.