Comparative assessment of orthodontic clear aligner versus fixed appliance for anterior retraction: a finite element study.

BACKGROUND: The aim of this study is to conduct a comparative evaluation of different designs of clear aligners and examine the disparities between clear aligners and fixed appliances. METHODS: 3D digital models were created, consisting of a maxillary dentition without first premolars, maxilla, periodontal ligaments, attachments, micro-implant, 3D printed lingual retractor, brackets, archwire and clear aligner. The study involved the creation of five design models for clear aligner maxillary anterior internal retraction and one design model for fixed appliance maxillary anterior internal retraction, which were subsequently subjected to finite element analysis. These design models included: (1) Model C0 Control, (2) Model C1 Posterior Micro-implant, (3) Model C2 Anterior Micro-implant, (4) Model C3 Palatal Plate, (5) Model C4 Lingual Retractor, and (6) Model F0 Fixed Appliance. RESULTS: In the clear aligner models, a consistent pattern of tooth movement was observed. Notably, among all tested models, the modified clear aligner Model C3 exhibited the smallest differences in sagittal displacement of the crown-root of the central incisor, vertical displacement of the central incisor, sagittal displacement of the second premolar and second molar, as well as vertical displacement of posterior teeth. However, distinct variations in tooth movement trends were observed between the clear aligner models and the fixed appliance model. Furthermore, compared to the fixed appliance model, significant increases in tooth displacement were achieved with the use of clear aligner models. CONCLUSIONS: In the clear aligner models, the movement trend of the teeth remained consistent, but there were variations in the amount of tooth displacement. Overall, the Model C3 exhibited better torque control and provided greater protection for posterior anchorage teeth compared to the other four clear aligner models. On the other hand, the fixed appliance model provides superior anterior torque control and better protection of the posterior anchorage teeth compared to clear aligner models. The clear aligner approach and the fixed appliance approach still exhibit a disparity; nevertheless, this study offers a developmental direction and establishes a theoretical foundation for future non-invasive, aesthetically pleasing, comfortable, and efficient modalities of clear aligner treatment.

Assessment of the efficacy of various maxillary molar intrusion therapies: a systematic review.

AIMS: To systematically assess the efficacy of the various interventions used to intrude maxillary molars. Furthermore, to evaluate associated root resorption, stability of intrusion, subsequent vertical movement of mandibular molars, cost effectiveness, compliance, patient reported outcomes and adverse events. METHODS: A pre-registered and comprehensive literature search of published and unpublished trials until March 22nd 2023 with no language restriction applied in PubMed/Medline, Embase, Scopus, DOSS, CENTRAL, CINAHL Plus with Full Text, Web of Science, Global Index Medicus, Dissertation and Theses Global, ClinicalTrials.gov, and Trip (PROSPERO: CRD42022310562). Randomized controlled trials involving a comparative assessment of treatment modalities used to intrude maxillary molars were included. Pre-piloted data extraction forms were used. The Cochrane Risk of Bias tool was used for risk of bias assessment, and The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was used for certainty of evidence appraisal. RESULTS: A total of 3986 records were identified through the electronic data search, of which 24 reports were sought for retrieval. Of these, 7 trials were included. One trial was judged at high risk of bias, while the others had some concerns. Based on individual small sample studies, maxillary molar intrusion was achieved using temporary anchorage devices (TADs) and rapid molar intruder appliance (RMI). It was also observed to a lesser extent with the use of open bite bionator (OBB) and posterior bite blocks. The molar intruder appliance and the posterior bite blocks (spring-loaded or magnetic) also intruded the lower molars. Root resorption was reported in two studies involving TADs. None of the identified studies involved a comparison of conventional and TAD-based treatments for intrusion of molars. No studies reported outcomes concerning stability, cost-effectiveness, compliance and patient-reported outcomes. Insufficient homogeneity between the included trials precluded quantitative synthesis. The level of evidence was very low. CONCLUSIONS: Maxillary molar intrusion can be attained with different appliances (removable and fixed) and with the use of temporary anchorage devices. Posterior bite blocks (spring-loaded or magnetic) and the RMI offer the additional advantage of intruding the mandibular molars. However, stability of the achieved maxillary molar intrusion long term is unclear. Further high-quality randomized controlled trials are needed.

Tomographic assessment of infrazygomatic crest bone depth for extra-alveolar miniscrew insertion in subjects with different vertical and sagittal skeletal patterns.

OBJECTIVE: To evaluate bone availability at the infrazygomatic crest for extra-alveolar bone miniscrew insertion in subjects with different vertical and sagittal skeletal patterns. SETTING AND SAMPLE POPULATION: Measurements of the infrazygomatic crest were performed on multislice computed tomography scans from 58 adults with different skeletal patterns. MATERIALS AND METHODS: Infrazygomatic crest bone depth was measured at 4, 5 and 6 mm from the cementoenamel junction (CEJ) of the maxillary first molar at three different angles (60°, 70° and 80°) in the first molar occlusal plane. The sagittal and vertical skeletal patterns were determined. Analysis of variance followed by Tukey's post hoc test was used (P ≤ .05). RESULTS: Bone depth was greater near the CEJ (8.7 ± 3.1 mm) and lower in the apical area (5.8 ± 2.7 mm). In Class II subjects, considering 6 mm from the CEJ, there was a significantly lower depth at the 80° angle (5.4 ± 2.5 mm) than at 60° (8.6 ± 3.5 mm; P = .007). In mesofacial subjects, considering 5 and 6 mm from the CEJ, bone depth was lower at 80° (5.7 ± 3.2 mm and 5.3 ± 2.5 mm) than at 60° considering 4 mm from the CEJ (P ≤ .019). CONCLUSION: Bone availability was lower at the apical level, especially in Class II and mesofacial subjects. Therefore, when the planned insertion site is located in the apical direction, it is recommended to choose shorter miniscrews (2.0 x 12mm) and a smaller insertion angle (60°) and/or to plan a miniscrew bone insertion deep enough to allow bicortical fixation.

Ortho-Perio Risk Assessment and timing flowchart for lingual orthodontics in an interdisciplinary adult ortho-perio patient: A case report of "Perio-Guided" Orthodontic treatment.

INTRODUCTION: The treatment of ortho-perio patients is a challenge for the interdisciplinary team. Not only are adult patients with overt perio pathology involved, but any ortho patient, even young ones, can be a perio patient and vice versa. Diagnosis and risk assessment of every ortho-perio patient is essential to establish a correct treatment plan, schedule and prognosis. Orthodontics becomes a "Perio-Guided" Orthodontic Treatment and Periodontics a "Ortho-Guided Periodontal Treatment". MATERIAL AND METHODS: This case report presents a man with a very compromised dentition asking for a complete interdisciplinary rehabilitation treated with a combined ortho-perio treatment in lingual mechanics. The periodontal evaluation confirmed the possibility of performing orthodontic treatment after active periodontal treatment. Treatment objectives were the resolution of the crowding, the correction of the levels of the gingival margin, the bone levelling, the preparation for restorative spaces; the objectives of the latter prior to implant placement were: redistribution of space, optimization of the position of adjacent teeth and their parallelism, exploitation of edentulous sites to correct dental class II and placement of the least number of implants possible. After integrating the conventional perio risk assessment with a new Ortho-Perio Risk Assessment (OPRA), a lingual fixed appliance was applied with the help of miniscrews to correct class II division 2 by substituting the upper right first premolar into a canine and retracting the entire upper arch, while correcting the deep bite and optimising the occlusion. RESULTS: At the end of the treatment, the patient had molar relationships of class II on the right and class I on the left with a class I canine and the 14 in the position of 13. Incisal relationships were corrected, the position of the incisors was optimized, the spaces in the upper arch were fully resolved by orthodontics. During the treatment, orthodontics corrected the uneven gingival margin of the anterior teeth and levelled the bone. CONCLUSIONS: Correct ortho-perio risk assessment (OPRA) is necessary to plan the risk of expression of the periodontal phenotype in ortho-patient. OPRA and the lingual mechanics allowed an orthodontic resolution of the malocclusion and an enhancement of the perio-implant-restorative contributions. OPRA followed by periodontal therapy and lingual mechanics resolved the malocclusion by improving the restorative peri-implant conditions. Orthodontists and periodontists should be aware of the characteristics of the individual expression of the periodontal phenotype at the beginning of treatment and involve patients in the outcome, sequencing of combined treatments, ortho-perio retention and stability.

Three-dimensional assessment of two different canine retraction techniques: a randomized split-mouth clinical trial.

INTRODUCTION: The aim of this split-mouth trial was to compare power-arm sliding (PAS) and direct sliding (DS) canine retraction mechanics in terms of speed, rotation, angulation, and anchorage loss. METHODS: Thirty-six class II division 1 patients (20 females, 16 males; mean age, 16.94 ± 3.23) requiring upper first premolar extraction were included in the study. Miniscrews were used as anchorage units, and a retraction force of 150 gr was applied from the power arm on one side and from the bracket on the opposite side by using elastomeric chains. Randomization was achieved by block randomization with a 1:1 allocation ratio either to the right or the left with allocations concealed in opaque, sealed envelopes. Digital models were acquired using an intraoral scanner at the beginning of the retraction (T0), the first month (T1), the second month (T2), and the third month (T3). Before the scans, the archwire was removed, and custom metal jigs were inserted into the vertical slot of the canine brackets to evaluate the canine angulation. The digital models of each patient were separately superimposed with the local best-fit algorithm, and the retraction rate, angulation, rotation, and anchorage loss were measured. The digital measurements were performed using the Geomagic Control X software. RESULTS: The DS technique's total retraction rate was higher than that of the PAS technique (2.09 and 1.57, respectively, p = .002). There was, however, no significant difference between the two techniques in terms of angulation, rotation, and anchorage loss. A negative correlation was observed between the retraction rate and age, but it was not statistically significant. No significant difference was observed between the retraction rates of female and male participants in either retraction technique. CONCLUSIONS: For both orthodontists and patients, the DS technique is simpler and more convenient; thus, it is the preferred method for canine retraction. TRIAL REGISTRATION: The trial was not registered. PROTOCOL: The protocol was not published before the trial commencement.

Bone depth and thickness of different infrazygomatic crest miniscrew insertion paths between the first and second maxillary molars for distal tooth movement: A 3-dimensional assessment.

INTRODUCTION: This research aimed to measure the bone depth and thickness of different insertion paths for safe placement of infrazygomatic crest miniscrews between the first (U6) and second maxillary molars (U7) by 3-dimensional (3D) reconstruction and to explore their clinical significance. METHODS: Cone-beam computed tomography data from 36 adult orthodontic patients were obtained to generate 3D models (n = 72) of the infrazygomatic crest region. For each model, the bone depth and thickness of 27 different insertion paths were measured in the region between U6 and U7. The relationship between bone depth and thickness was statistically analyzed. The clinical risk for each insertion path was assessed according to the impacts of bone depth and thickness on insertion failure. RESULTS: Maximum bone depth (median, 7.41 mm; mean, 8.42 mm) was present at 13 mm insertion sites with a gingival tipping angle of 50° and a distal tipping angle of 30°. Maximum bone thickness (median, 3.73 mm; mean, 4.00 mm) was present at 17 mm insertion site with a gingival tipping angle of 70° and a distal tipping angle of 30°. There was a significant negative correlation between bone depth and bone thickness (rs = -0.569, P <0.001). Failure rates were significantly different among different insertion paths (P <0.001). CONCLUSIONS: Because the bone depth and thickness may affect the safe insertion of infrazygomatic crest miniscrews in the region between U6 and U7 and they are negatively related, a safe insertion protocol design for distal tooth movement should take both into consideration.

Computed tomography assessment of maxillary bone density for orthodontic mini-implant placement with respect to vertical growth patterns.

OBJECTIVE: To quantitatively measure and report bone density of maxilla in the interradicular (alveolar and basal bone) and infrazygomatic crest (IZC) region in various growth patterns among Dravidian individuals. DESIGN: This was a retrospective spiral computed tomography (CT) study. SETTING: The study was conducted at the Department of Orthodontics, Saveetha Dental College and Hospital, Tamil Nadu, India. METHODS: Sixty CT scans (24 men, 36 women; mean age = 25.3 years and 23.8 years, respectively) divided equally into three groups based on vertical facial proportions were included. Bone density measurements in Hounsfield units (HU) were performed using Philips and RadiAnt DICOM viewers. Buccal cortical, palatal cortical and cancellous bone regions were analysed in a Philips DICOM viewer and IZC region was analysed in a RadiAnt DICOM viewer. Statistical analysis with one-way ANOVA and post-hoc Tukey HSD test was done. RESULTS: The hypodivergent group had a significantly higher bone density at the buccal cortex in posterior region (P < 0.05) when compared to the normodivergent and hyperdivergent groups. Buccal basal bone was denser than buccal alveolar bone (P < 0.05) in all three groups. In the IZC region, hypodivergent groups had significantly higher density values when compared to the normodivergent and hyperdivergent groups (P < 0.05). CONCLUSION: The present study concluded that cancellous bone density in the interradicular regions was greatest in the anterior sites and was not influenced by growth pattern. Hypodivergent groups tend to have higher density in the posterior regions (buccal and palatal cortical bone) and at the IZC region compared to normodivergent and hyperdivergent groups.

Assessment of Insertion Torque of Mini-implant and Its Correlation with Primary Stability and Pain Levels in Orthodontic Patients.

AIM: The aim of this study was to assess the insertion torque of the mini-implant used in orthodontic patients and to assess the correlation between the insertion torque, primary stability, and perception of pain in patients undergoing orthodontic therapy with mini-implant-augmented anchorage. MATERIAL AND METHODS: Among the patients undergoing orthodontic therapy, 31 samples who required mini-implant for anchorage purpose were selected. A total of 59 mini-implants were placed in these patients. This included interradicular mini-implants and extra-alveolar mini-screws. Immediately after placement, the insertion torque in all these was measured using a digital torque meter and primary stability was assessed by identifying any mobility of the implant placed. Primary stability was noted at two time intervals immediate post-placement and 1 week after that. All the mini-implants that were considered in this study were immediately loaded. Patients were asked to record any pain experienced on the visual analog scale (VAS) score sheet at 24 hours and 1 week post-placement. RESULTS: Among the mini-implants placed, those with 2 mm diameter needed higher placement torque, i.e., infrazygomatic crest mini-implants and buccal shelf mini-implants were placed with average placement torque of 10.08 and 10.25 N cm, respectively. Extra-alveolar screws caused more pain, especially higher in the mandible than the maxilla. Decrease in pain scores was noted from T0 to T1 in almost all the cases. CONCLUSION: Thicker mini-implant needed more insertion torque and highest insertion torque was recorded with extra-alveolar screws. No direct correlation could be obtained with the pain levels experienced by the patients and with the primary stability of the mini-implants. CLINICAL SIGNIFICANCE: Mini-implants placed with an insertion torque above the recommended range tend to fail and break more often. Patients placed with extra-alveolar bone screws reported more pain than that of the smaller-dimension mini-implant.

Anatomical assessment by cone beam computed tomography with the use of lateral cephalograms to analyse the vertical bone height of the anterior palate for orthodontic mini-implants.

OBJECTIVE: Lateral cephalograms (LC) should be usable to evaluate the vertical bone height of the anterior maxilla for planning the placement of orthodontic mini-implants (OMI). The purpose of this study is to determine the usability of LC for examining the real vertical dimension of the anterior palate. SETTING AND SAMPLE POPULATION: Lateral cephalograms and corresponding cone beam computed tomography (CBCT) scans were employed for examining 30 fresh cadaver heads. MATERIALS & METHODS: The minimum (distance A) and maximum (distance B) vertical palatal bone heights on LCs at the level of first premolars were measured, whereas the corresponding measurements were taken via CBCTs on the median, and 2-, 4- and 6-mm paramedian planes. Additionally, the overall minimum vertical palatal height on CBCT was recorded. RESULTS: Distance A and B on LC were about 8.3 ± 2.5 mm and 9.9 ± 2.5 mm, respectively. The median palatal height on CBCT was significantly higher than both measurements on LC (P < .01). Furthermore, the bone supply on the paramedian planes was similar or higher on CBCT compared to Distance A and similar or less compared to Distance B. The strongest correlation at the level of the premolars was found in the comparison of the maximum vertical palatal height via LC with the vertical palatal height on the median plane via CBCT (r = .84, 95% CI: 0.69-0.92, P < .001). CONCLUSIONS: In order to make the best possible use of the vertical bone supply of the anterior palate and to avoid injuries to the nasal floor, Distance A should be taken into account for planning paramedian OMI placements and distance B for median OMI insertion.

Assessment of the mandibular buccal shelf for orthodontic anchorage: Influence of side, gender and skeletal patterns.

OBJECTIVES: To evaluate bone height and thickness in the mandibular buccal shelf region and to compare differences between anatomical sites according to gender, side and vertical and sagittal skeletal patterns. SETTINGS AND SAMPLE POPULATION: Multislice computed tomography (MSCT) images of 94 subjects (51 females and 43 males) were previously obtained as part of preoperative planning for orthognathic surgery. METHODS: Measurements were performed in three different regions of the mandibular buccal shelf: mesially, towards the central groove and distally to the second molars. Bone thickness measurements were obtained perpendicularly 3, 5 and 7 mm below the bone crest towards the mandible outer cortex. Bone height was measured 3 mm away from the bone crest perpendicularly to the outer cortex of the base of mandible. RESULTS: There was an increase in bone thickness in the posterior and basal directions. The increase in bone thickness ranged from 1.8 to 7.1 mm. Greater bone height was found in the anterior direction. The increase in bone height ranged from 17.5 to 22.5 mm. Hypodivergent and Class III subjects showed significantly greater bone thickness (P < .05). Significantly greater bone height was found mesially to the second molar in Class III subjects compared with Class I subjects (P < .05) and in hyperdivergent males compared with hypodivergent males (P < .05). CONCLUSIONS: The region distal to the second molar is the most appropriate for the insertion of extra-alveolar mini-screws in terms of bone thickness. Hypodivergent and Class III subjects showed greater bone thickness in the mandibular buccal shelf region.

Assessment of available sites for palatal orthodontic mini-implants through cone-beam computed tomography.

OBJECTIVE: To measure the palatal thickness of both hard and soft tissues and to determine safe regions for the placement of mini-implants. The influences of sex and age on palatal thickness were also examined. MATERIALS AND METHODS: Cone-beam computed tomography images of 30 patients (12 males, 18 females), including 15 adults and 15 adolescents, were used in this study. The thicknesses of palatal hard tissue, soft tissue, and hard+soft tissues were measured at the coronal planes of first premolars, second premolars, first molars, and second molars (P1, P2, M1, and M2 planes, respectively). RESULTS: The hard tissue was thickest at the P1 plane, followed by at the P2, M1, and M2 planes, while the thickness of soft tissue was similar among the four planes. The trends in the changes of palatal thickness from midline to the lateral sides (V-pattern) were similar for the four planes. Palatal thickness was influenced by sex, age, and their interaction. Mapping of recommended and optimal sites for palatal mini-implants was accomplished. CONCLUSIONS: Sex and age factors could influence palatal thickness. Therefore, the findings might be helpful for clinicians in guiding them to choose the optimal sites for palatal mini-implants.

Assessment of stiffness and load deflection of orthodontic miniscrews used for palatal anchorage: An in vitro biomechanical study.

OBJECTIVE: The purpose of this study was to evaluate the biomechanical properties of miniscrews of 5 different lengths, 2 different diameters, and different combinations of insertion used for palatal skeletal anchorage. MATERIALS AND METHODS: Twenty-four different combinations of a total of 120 miniscrews of two different diameters (2.0mm and 2.3mm) and five different lengths (9mm, 11mm, 13mm and 15mm) were tested at different angles of insertion (90° and 45°) and distances from a synthetic bone block (3mm, 5mm, 7mm). Samples were fixed in an Instron Universal Testing Machine and a load was applied in single cantilever mode to the neck of each miniscrew. The stiffness and maximum load before permanent deformation were recorded. Model-based recursive partitioning testing (CART) was used to evaluate differences between groups. RESULTS: Significantly higher forces were necessary to deform miniscrews of diameter 2.3mm than those of 2.0mm, those inserted at an angle of 45° with respect to 90°, and at smaller distances between the miniscrew neck and block; in addition, the maximum load and stiffness increased with increasing screw length. CONCLUSION: This in vitro experimental study showed strong correlations between deformation load and miniscrew geometry, insertion angle and distance from the synthetic block, results that should be considered when planning miniscrew insertion in order to reduce the risk of unwanted fracture.

Assessment of the cortical bone thickness by CT-scan and its association with orthodontic implant position in a young adult Eastern Mediterranean population: A cross sectional study.

OBJECTIVE: This study was conducted to assess cortical bone thickness in the alveolar process of maxilla and mandible and to investigate its association with different orthodontic implant positions in Eastern Mediterranean young adults. MATERIALS AND METHODS: Computed tomography images of 50 patients aged between 18-35 years were included. Buccal, palatal and lingual cortical bone thicknesses were measured at 2, 4, 6, and 8mm from cemento-enamel junction starting from the mesial side of the second molar to the contralateral side. Pearson correlation was used to assess the association between cortical bone thickness and proposed orthodontic implant positions at all inter-radicular sites (p<0.05). RESULTS: The highest value of buccal cortical bone thickness was found mesial to the second molar in the maxilla and mandible for both genders. The value of palatal cortical bone thickness was found to be at the highest rate mesial to canine and first premolar in males and females respectively. On the other hand, the highest value of lingual cortical bone thickness was recorded to be mesial to the first molar in both genders. In addition to that, the buccal cortical bone thickness was significantly higher than palatal at the area mesial to the second molar at all four levels from the cemento-enamel junction. A significant correlation was found between cortical bone thickness and 2, 4, 6, and 8mm orthodontic implant levels in all inter-radicular sites. The values of correlation coefficients ranged from 0.280 to 0.674 in the maxillary arch and from 0.266 to 0.605 in the mandibular arch. CONCLUSIONS: From this study, we can conclude that as the position of the orthodontic implant moved more posteriorly and apically more cortical bone thickness was expected to be found in both jaws. A significant correlation was found between cortical bone thickness and the site of the orthodontic implant. Cortical bone thickness and its relationship with implant position should be taken into consideration when attempts are made to insert the orthodontic implant.

Assessment of the changes in the oral health related quality of life 24 hours following insertion of fixed orthodontic appliance components - An observational cross-sectional study conducted at Bahria University Medical and Dental College Karachi.

OBJECTIVE: To evaluate the changes in Oral Health Related Quality of Life 24 hours following insertion of fixed orthodontic appliance components, and to compare the results between different age groups and genders. METHODS: The observational cross-sectional study was conducted from July to December 2017 at Bahria University Medical and Dental College, Karachi, and comprised patients from the Orthodontics outpatient department enrolled via convenience sampling. Oral Health Impact Profile questionnaire was used to assess the Oral Health Related Quality of Life after placement of separators, bands and brackets. Patients were assessed before the appliances were placed and 24 hours after the insertions. Changes were evaluated and age and gender groups were compared using SPSS 17. RESULTS: Of the 70 patients, 20(28%) were males and 50(72%) were females. The overall mean age of the sample was 18.3}3.8 years. Oral Health Impact Profile scores showed significant deterioration of oral health quality 24 hours after the placement of brackets (p<0.05). However, there was no significant deterioration of lack of self-confidence (p=0.19), avoid smiling (p=0.11) and embarrassment (p=0.62) after the placement of separators and bands. There was no significant difference across genders (p>0.05), but young adults had significantly higher mean difference compared to adolescents after placement of bands (p<0.05). CONCLUSIONS: The Oral Health Related Quality of Life significantly deteriorated 24hours following the insertion of separators, bands and brackets.

Three-dimensional quantitative assessment of palatal bone height for insertion of orthodontic implants - a retrospective CBCT study.

BACKGROUND: Orthodontic implants have found widespread use as means of maximum skeletal anchorage in fixed orthodontic treatment, their optimal insertion location in the hard palate, however, is still controversial. The aim of this study was therefore to assess mean bone height across the hard palate and possible age- and sex related differences to identify the most favourable location according to maximum bone height, optimizing primary stability and survival of inserted orthodontic implants. METHODS: In this retrospective cross-sectional study, maxillary pretreatment CBCT scans of 180 healthy orthodontic patients (95♀, 85♂, age 8-40 years) were analysed with regard to vertical palatal bone height in the midpalatal area at 88 validated points distanced 2 mm from each other forming a grid of 0-14 mm posterior to the incisive foramen and 10 mm lateral of the midpalatal suture. Differences in bone height regarding sex and topographical location were assessed by three-way ANOVA. RESULTS: In general, the midpalatal suture as well as the anterior-lateral palatal region showed distinctly higher mean palatal bone height with its maximum 4 mm posterior of the incisive foramen, whereas bone height was limited at the posterior region of the midpalatal suture. Women generally had significantly decreased palatal bone height compared to men at all measurement points. Higher age was associated with a decrease of bone height in the anterior and posterior lateral palatal region and the median palatal raphe with significant age differences. CONCLUSIONS: The midpalatal suture as well as the anterior lateral palate seem to be most suitable for the insertion of orthodontic implants. Palatal bone height, however, was found to be sex- and age-specific, thus sex- and age-related differences should be taken into account, particularly regarding implant length. The ideal insertion site in the palate with sufficient bone height for orthodontic implants is 0-8 mm (men) or 0-6 mm (women) posterior to the incisive foramen and 10 mm lateral to the midpalatal suture. TRIAL REGISTRAION: This study has been registered and approved by the Ethics Committee of the University of Witten/Herdecke, Germany (12/2016).

Anchorage loss assessment of the indirect anchor tooth during adjunctive orthodontic treatment.

INTRODUCTION: This study quantitatively assessed movement of anchor teeth connected to a miniscrew (indirect anchor tooth) and investigated factors affecting movement during adjunctive orthodontic treatment. METHODS: Dental plaster models of 28 patients whose treatment included an indirect anchor tooth on one side were collected before and after treatment. The casts were digitally scanned, and 2 groups were constituted: the indirect anchor teeth (experimental group; n = 52) and the untreated teeth (control group; the first and second premolars opposing the indirect anchor tooth to which no orthodontic force was applied; n = 55). Pretreatment and posttreatment models were superimposed and the amount and direction of indirect anchor tooth movement were evaluated with the use of a univariate linear mixed model. Possible factors affecting movement of the indirect anchor tooth and its significance were also evaluated with the use of a multiple linear mixed model. RESULTS: The indirect anchor tooth moved 0.91 ± 0.50 mm and did not exhibit significant differences in the transverse, vertical, or sagittal directions. The location of the indirect anchor tooth affected movement and the tooth moved significantly more in the mandible than in the maxilla. CONCLUSIONS: The indirect anchor tooth can move during adjunctive orthodontic treatment and thus requires careful monitoring for occlusal changes.

A cost-effectiveness analysis of anchorage reinforcement with miniscrews and molar blocks in adolescents: a randomized controlled trial.

OBJECTIVE: To analyse cost-effectiveness of anchorage reinforcement with buccal miniscrews and with molar blocks. We hypothesized that anchorage with miniscrews is more cost-effective than anchorage with molar blocks. TRIAL DESIGN: A single-centre, two-arm parallel-group randomized controlled trial. METHODS: Adolescents (age 11-19 years) in need of treatment with fixed appliance, premolar extractions, and en masse retraction were recruited from one Public Dental Health specialist centre. The intervention arm received anchorage reinforcement with buccal miniscrews during space closure. The active comparator received anchorage reinforcement with molar blocks during levelling/alignment and space closure. The primary outcome measure was societal costs defined as the sum of direct and indirect costs. Randomization was conducted as simple randomization stratified on gender. The patients, caregivers, and outcome assessors were not blinded. RESULTS: Eighty patients were randomized into two groups. The trial is completed. All patients were included in the intention-to-treat analysis. The median societal costs for the miniscrew group were €4681 and for the molar block group were €3609. The median of the difference was €825 (95% confidence interval (CI) 431-1267). This difference was mainly caused by significantly higher direct costs consisting of material and chair time costs. Differences in chair time costs were related to longer treatment duration. No serious harms were detected, one screw fractured during insertion and three screws were lost during treatment. GENERALIZABILITY AND LIMITATIONS: The monetary variables are calculated based on a number of local factors and assumptions and cannot necessarily be transferred to other countries. Variables such as chair time, number of appointments, and treatment duration are generalizable. Owing to the study protocol, the benefit of miniscrews as a stable anchorage has not been fully utilized. CONCLUSIONS: When only moderate anchorage reinforcement is needed, miniscrews are less cost-effective than molar blocks. The initial hypothesis was rejected. Miniscrews provide better anchorage reinforcement at a higher price. They should be used in cases where anchorage loss cannot be accepted. TRIAL REGISTRATION: NCT02644811.

Three-dimensional assessment of external apical root resorption after maxillary posterior teeth intrusion with miniscrews in anterior open bite patients

ABSTRACT Objective: The objective of this study was to assess the external apical root resorption (EARR) of the maxillary posterior teeth after intrusion with miniscrews. Methods: Fifteen patients (13 females and 2 males) with age ranging from 14.5 to 22 years (mean 18.1 ±2.03 years) were selected to participate in this study. All patients presented with anterior open bite of 3 mm or more. An intrusion force of 300 g was applied on each side to intrude the maxillary posterior teeth. Cone beam computed tomography (CBCT) scans were taken pretreatment and post-intrusion and were analyzed to evaluate the EARR. Results: The maxillary posterior teeth were intruded in average 2.79 ± 0.46 mm (p< 0.001) in 5.1 ± 1.3 months, and all examined roots showed statistically significant EARR (p< 0.05) with an average of 0.55 mm, except the distobuccal root of the left first permanent molars and both the palatal and buccal roots of left first premolars, which showed no statistically significant changes. Conclusions: The evaluated teeth presented statistically significant EARR, but clinically, due to the small magnitude, it was not considered significant. Moreover, the CBCT provided a good visualization of all roots in all three planes, and it was effective in detecting minimal degrees of EARR.

RESUMO Objetivo: o objetivo desse estudo foi verificar a existência de reabsorção radicular apical externa (RRAE) em dentes posterossuperiores após intrusão ancorada em mini-implantes. Métodos: quinze pacientes (13 mulheres e 2 homens) com a idade variando entre 14,5 e 22 anos (média de 18,1 ± 2,03 anos) foram selecionados para participar desse estudo. Todos os pacientes possuíam mordida aberta anterior de 3mm ou mais. Uma força de 300 gramas foi aplicada em cada lado para intruir os dentes posterossuperiores. Tomografias computadorizadas de feixe cônico (TCFC), adquiridas antes do tratamento e após a intrusão, foram comparadas para se avaliar a RRAE. Resultados: os dentes posterossuperiores foram intruídos em média 2,70 ± 0,46 mm (p< 0,001) em 5,1 ± 1,3 meses, e todas as raízes examinadas mostraram RRAE estatisticamente significativa (p< 0,05), com média de 0,55 mm, exceto pela raiz distovestibular dos primeiros molares permanentes esquerdos, e pelas raízes palatina e vestibular dos primeiros pré-molares esquerdos, que não apresentaram mudanças estatisticamente significativas. Conclusões: os dentes avaliados apresentaram RRAE estatisticamente significativa, a qual, porém, não foi considerada clinicamente significativa, devido à sua reduzida magnitude. Além disso, a TCFC possibilitou uma boa visualização de todas as raízes nos três planos espaciais, e foi eficaz para detecção de níveis mínimos de RRAE.

Anatomic assessment of the mandibular buccal shelf for miniscrew insertion in white patients.

INTRODUCTION: Cortical bone thickness, bone width, insertion depth, and proximity to nerves are important factors when planning and placing orthodontic miniscrews. The objective of this study was to anatomically assess the mandibular buccal shelf in a white patient population as the insertion site for orthodontic miniscrews by investigating these 4 variables. METHODS: Measurements were made on cone-beam computed tomography scans of 30 white patients (18 girls, 12 boys; mean age, 14.5 ± 2 years). All measurements were taken adjacent to the distobuccal cusp of the first molar, and the mesiobuccal and distobuccal cusps of the second molar. Additionally, bone depth was measured at 2 height levels, 4 and 8 mm from the cementoenamel junction. Stereolithographic models of patients were superimposed on the cone-beam computed tomography volumes to virtually create an outline of the soft tissue on the cone-beam computed tomography image to allow identification of the purchase point height (mucogingival junction). The inferior alveolar nerve was digitally traced. Miniscrews (1.6 × 10 mm) were virtually placed at the buccal shelf, and their insertion depths and relationships to the nerve were assessed. Analysis of variance with post hoc analysis was used for data analysis. RESULTS: Insertion sites and measurement levels had significant impacts on both cortical bone thickness and bone width. Cortical bone thickness was typically greatest at the distobuccal cusp of the second molar. Bone width was also greatest at the distobuccal cusp of the second molar 8 mm from the cementoenamel junction. The greatest insertion depth was found again at the distobuccal cusp to the second molar, whereas the miniscrews had the greatest proximity to the nerve at this site also. CONCLUSIONS: The distobuccal cusp level of the mandibular second molar is the most appropriate site for miniscrew insertion at the buccal shelf in white patients.

Assessment of changes in the nasal airway after nonsurgical miniscrew-assisted rapid maxillary expansion in young adults.

OBJECTIVES: To evaluate changes in the volume and cross-sectional area of the nasal airway before and 1 year after nonsurgical miniscrew-assisted rapid maxillary expansion (MARME) in young adults. MATERIALS AND METHODS: Fourteen patients (mean age, 22.7 years; 10 women, four men) with a transverse discrepancy who underwent cone beam computed tomography before (T0), immediately after (T1), and 1 year after (T2) expansion were retrospectively included in this study. The volume of the nasal cavity and nasopharynx and the cross-sectional area of the anterior, middle, and posterior segments of the nasal airway were measured and compared among the three timepoints using paired t-tests. RESULTS: The volume of the nasal cavity showed a significant increase at T1 and T2 ( P < .05), while that of the nasopharynx increased only at T2 ( P < .05). The anterior and middle cross-sectional areas significantly increased at T1 and T2 ( P < .05), while the posterior cross-sectional area showed no significant change throughout the observation period ( P > .05). CONCLUSIONS: The results demonstrate that the volume and cross-sectional area of the nasal cavity increased after MARME and were maintained at 1 year after expansion. Therefore, MARME may be helpful in expanding the nasal airway.