Risk of root damage after using lateral cephalogram and intraoral scan for guided insertion of palatal miniscrews.

BACKGROUND: Guided insertion of palatal miniscrews using a lateral cephalogram instead of cone beam computed tomography (CBCT) significantly reduces the radiation level for the patient. Till now no data are available on the risk of hitting the incisors in this regard, which is one of the worst clinical complications when inserting a paramedian miniscrew. Hence, this study aims to investigate the distance between the mini-implant and the roots of the central and lateral incisors. METHODS: Lateral cephalogram, an intraoral scan, and CBCT of 20 patients were superimposed. After a miniscrew (1.7 × 8 mm) placement based on intraoral scan and lateral cephalogram, the CBCT was used as control for the distance between the miniscrews and the roots of the incisors. RESULTS: The mean value of the shortest distance between the miniscrew and roots of the incisors in the lateral cephalogram was 4.74 ± 1.67 mm. The distance between both miniscrews and the central incisors measured in the CBCT was 5.03 ± 2.22 mm and 5.26 ± 2.21 mm and between the two miniscrews and the lateral incisors was 4.93 ± 1.91 mm and 5.21 ± 2.64 mm. No significant differences between the distances in the CBCT and the lateral cephalogram could be observed. In one case, the CBCT control revealed the penetration of two palatally displaced canines after insertion based on intraoral scan and lateral cephalogram. CONCLUSIONS: The use of an intraoral scan and a lateral cephalogram for guided paramedian insertion of palatal miniscrews can prevent incisor root damage. This may reduce the radiation since no CBCT seems necessary. The current investigation focuses on the anterior paramedian area of the palate. Outside that region and in complex cases with displaced teeth in the palatal area, a CBCT might be indicated.

The Effects of Additional Filtration on Image Quality and Radiation Dose in Cone Beam CT: An In Vivo Preliminary Investigation.

Purpose: The aim of this study was to investigate the effect of reduced radiation doses on the image quality of cone-beam computed tomography scans and the suitability of such imaging for orthodontics, oral surgery, dental implantology, periodontology, and endodontology. Materials and Methods: Cone-beam computed tomography scans of a live patient were performed using seven attenuation filters with increased thickness to decrease the effective radiation dose from 22.4 to 1.8 µSv, and the effects of different radiation doses on image quality were further analysed. Quantitative image quality was calculated using dedicated measures, such as signal and contrast-to-noise ratio and sharpness. A panel of five certified raters assessed the cone-beam computed tomography scans qualitatively. Nine anatomical structures relevant to dentistry were identified, and the overall acceptance was assessed. Results: Linear reduction of the effective radiation dose had a nonlinear effect on image quality. A 5-fold reduction in the effective dose led to acceptable quantitative and qualitative image quality measures, and the identification rate of dental anatomical structures was 80% or greater. The use of less than 40% of the reference dose was unacceptable for all dental specialties. Conclusions: The ideal radiation dose for specific diagnostic requirements remains a patient-related and specialty-related decision that must be made on an individual basis. Based on the results of this study, it is possible to reduce exposure in selected patients, and at the same time obtain sufficient quality of images for clinical purposes.

Bone remodelling patterns around orthodontic mini-implants migrating in bone: an experimental study in rat vertebrae.

BACKGROUND: Orthodontic implant migration has been clinically observed in presence of continuous loading forces. Recent studies indicate that osteocytes play a crucial role in this phenomenon. OBJECTIVES: Aim of this study was to investigate local osteocytic gene expression, protein expression, and bone micro-structure in peri-implant regions of pressure and tension. MATERIAL AND METHODS: The present work reports a complementary analysis to a previous micro-computed tomography study. Two customized mini-implants were placed in one caudal rat vertebra and connected by a nickel-titanium contraction spring generating different forces (i.e. 0, 0.5, 1.0, and 1.5 N). Either at 2 or 8 weeks, the vertebrae were harvested and utilized for 1. osteocytic gene expression using laser capture micro-dissection on frozen sections coupled with qPCR, 2. haematoxylin-eosin staining for qualitative and quantitative analyses, 3. immunofluorescence staining and analysis, and 4. bone-to-implant contact on undecalcified samples. RESULTS: At the two time points for all the performed analyses no significant differences were observed with respect to the applied force magnitudes and cell harvesting localization. However, descriptive histological analysis revealed remarkable bone remodelling at 2 weeks of loading. At 8 weeks the implants were osseointegrated and, especially in 1.0 and 1.5 N groups, newly formed bone presented a characteristic load bearing architecture with trabecula oriented in the direction of the loading. CONCLUSIONS: The present study confirmed that stress-induced bone remodelling is the biological mechanism of orthodontic implant migration. Bone apposition was found at 'tension' and 'pressure' sites thus limiting implant migration over time.

Microstructural volumetric analysis of vertical alveolar ridge augmentation using autogenous tooth roots.

BACKGROUND: To volumetrically assess the bone microstructure following vertical alveolar ridge augmentation using differently conditioned autogenous tooth roots (TR) and second-stage implant placement. MATERIALS AND METHODS: The upper premolars were bilaterally extracted in n = 4 beagle dogs and randomly assigned to either autoclavation (TR-A) or no additional treatment (TR-C). Subsequently, TR were used as block grafts for vertical alveolar ridge augmentation in both lower quadrants. At 12 weeks, titanium implants were inserted and left to heal 3 weeks. Microcomputed tomography was used to quantify bone volume per tissue volume (BV/TV), trabecular thickness (Tb.Th), and trabecular spacing (Tb.Sp) at vestibular (v) and oral (o) aspects along the implant and in the augmented upper half of the implant, respectively. RESULTS: Median BV/TV [TR-C: 51.33% (v) and 70.42% (o) vs TR-A: 44.05% (v) and 64.46% (o)], Tb.th [TR-C: 0.22 mm (v) and 0.27 mm (o) vs TR-A: 0.23 mm (v) and 0.29 mm (o)] and Tb.Sp [TR-C: 0.26 mm (v) and 0.13 mm (o) vs TR-A: 0.29 µm (v) and 0.15 mm (o)] values were comparable in both groups. CONCLUSION: Both TR-C and TR-A grafts were associated with a comparable bone microstructure within the grafted area.

RFA measurements of survival midpalatal orthodontic mini-implants in comparison to initial healing period.

BACKGROUND: In dental implantology, the development of stability over time is a well-investigated topic. In case of orthodontic mini-implants, quantitative data for long-term stability is not available yet. This study aims to clinically investigate the long-term stability of mini-implants inserted in the midsagittal suture of the anterior palate. Moreover, the influence of the length of implants was elucidated. The stability of 2 × 9 and 2 × 11 mm mini-implants after orthodontic treatment (9 mm, 2.84 years ± 1.25 years; 11 mm, 3.17 years ± 0.96 years) was assessed by resonance frequency analysis (RFA). The obtained long-term pieces of data were compared with each other (9 mm vs 11 mm), as well as with the data from the matched early stability groups, to assess the initial and early secondary stability after the insertion from previous clinical trials. RESULTS: For both lengths, the long-term stability (2 × 9 mm, 25.12 ± 7.11, n = 21; 2 × 11 mm, 24.39 ± 5.82, n = 18) was significantly lower than primary stability (2 × 9 mm, 36.14 ± 6.08, n = 19; 2 × 11 mm, 33.35 ± 3.53, n = 20). The differences within the groups disappeared over the initial healing period: after 4 weeks for the 2 × 9 mm implants and after 2 weeks for the 2 × 11 mm implants. Also, the 2 × 9 mm and 2 × 11 mm implants showed comparable long-term stability values. CONCLUSION: The stability of midpalatal mini-implants does not change in the long term after the initial healing period. Moreover, 2 × 9 mm mini-implants seem to be appropriate for orthodontic anchorage, as the stability of 2 × 11 mm implants is not higher. Therefore, owing to lower invasiveness, 2 × 9 mm implants should be preferred.

Long-term stability behavior of paramedian palatal mini-implants: A repeated cross-sectional study.

INTRODUCTION: The initial stability of orthodontic mini-implants is well investigated over a period of 6 weeks. There is no clinical data available dealing with the long-term stability. The aim of this study was the assessment of long-term stability of paramedian palatal mini-implants in humans. METHODS: Stability of 20 implants was measured after removal of the orthodontic appliance (sliding mechanics for sagittal molar movement 200 cN each side) before explantation (T4) using resonance frequency analysis (RFA). Data were compared with a matched group of 21 mini-implants assessing the stability immediately after insertion, and after 2, 4, and 6 weeks (T0-T3). The mini-implants used in this study were machined self-drilling titanium implants (2.0 × 9.0 mm). Gingival thickness at the insertion site was 1-2 mm. RESULTS: The implant stability quotient (ISQ) values before removal of the implant at T4 were 25.2 ± 2.9 after 1.7 ± 0.2 years and did not show a statistically significant change over time compared with the initial healing group (T0-T3). CONCLUSIONS: Comparing the stability of mini-implants just after completion of the healing period and at the end of their respective usage period revealed no significant difference. An increase of secondary stability could not be detected. The level of stability seemed to be appropriate for orthodontic anchorage.

Early Class III treatment with Hybrid-Hyrax - Facemask in comparison to Hybrid-Hyrax-Mentoplate - skeletal and dental outcomes.

BACKGROUND: Protraction of maxilla is usually the preferred and more commonly used treatment approach for skeletal Class III with a retrognathic maxilla. The aim of this study was the comparison of the skeletal and dental effects of two skeletally borne appliances for maxillary protraction: a) Hybrid-Hyrax in combination with facemask (FM), b) Hybrid-Hyrax in combination with Mentoplate (ME). METHODS: Thirty four Patients (17 facemask, 17 Mentoplate) were investigated by means of pre- and posttreatment cephalograms. The two groups matched with regard to treatment time, age gender and type of dentoskeletal deformity before treatment. RESULTS: Both groups showed a significant forward movement of A-point (FM GROUP: SNA + 2.23° ± 1.30°- p 0.000*; ME: 2.23° ± 1.43°- p 0.000*). B-Point showed a larger sagittal change in the FM Group (SNB 1.51° ± 1.1°- p 0.000*) compared to the ME group (SNB: - 0.30° ± 0.9°- p 0.070). The FM group showed a significant increase of the ML-NL + 1.86° ± 1.65° (p 0.000*) and NSL-ML + 1.17° ± 1.48 (p 0.006*). Upper Incisor inclination did not change significantly during treatment in both groups as well as the distance of the first upper Molar in relation to A-point. CONCLUSION: Both treatments achieve comparable rates of maxillary protraction, without dentoalveolar side effects. Skeletal anchorage with symphysial plates in the mandible provides greater vertical control and might be the treatment of choice in high angle patients.

Therapeutic accuracy of the completely customized lingual appliance WIN : A retrospective cohort study.

OBJECTIVE: The aim of this retrospective cohort study was to assess the accuracy of the completely customized lingual appliance WIN (DW Lingual Systems, Bad Essen, Germany) employing a three-dimensional (3D) comparison between the setup and the final result. MATERIALS AND METHODS: The setup and final models of 20 consecutively debonded patients (40 jaws; 7 males, 13 females; mean age 15.76 ± 4.45 years) with various malocclusions of a private practice specialized in orthodontics were digitalized using a 3D scanner. The 3D models of the setup and the final model of each jaw were then digitally matched using the best fit algorithm and segmented into single teeth. After placing individual coordinate systems, the homologous teeth of the setup and the final model were matched to be able to calculate the exact deviations of all rotational and translational components. The t test for unpaired samples, Kruskal-Wallis tests, U tests, and ANOVA with Duncan post hoc test were applied statistically. RESULTS: Regarding the incisors, the angle discrepancies between the setup and the final result appeared to be less than 3° (torque 2.96°; tip 2.04°; rotation 2.00°). The translations showed mean values less than 0.3 mm (mesiodistal 0.16 mm; buccolingual 0.15 mm; vertical 0.29 mm). Slightly higher values could be measured in the lateral segments regarding rotations (torque 5.18°; tip 3.10°; rotation 3.70°) as well as regarding translations (mesiodistal 0.26 mm; buccolingual 0.64 mm; vertical 0.36 mm). CONCLUSIONS: Using the completely customized lingual appliance WIN, it is possible to achieve the final result predicted by the setup with a high accuracy.

The efficacy of Hybrid Hyrax-Mentoplate combination in early Class III treatment: a novel approach and pilot study.

INTRODUCTION: The aim of the present study was to assess the skeletal, dental and soft tissue effects of a specific treatment protocol in consecutively treated patients who presented with a Class III malocclusion. Treatment involved the use of a Hybrid Hyrax (HH) in the maxilla, a Mentoplate in the mandible and the application of continuous intra-oral Class III elastics. METHOD: The treated group was comprised of seven males and seven females (mean pretreatment age 10.4 ± 1.7 yr, range 7.8-12.9 yr). Treatment changes were analysed on lateral cephalograms taken 6-12 months prior to commencing treatment (T1) and at the finish of the orthopaedic phase (T2). Where a normality assumption was met, a parametric paired-sample t-test was used to assess the change differences at T1 and T2. For non-normal data, a non-parametric Wilcoxon sign rank test for related samples was used to assess T1 and T2 differences. The level of statistical significance was set at p < 0.05 (2-tailed). RESULTS: The average sagittal changes showed an improved SNA angle of 2.1 ± 2° (p = 0.002), an ANB angle of 1.9 ± 1.8° (p = 0.002), a Wits improvement of 3.4 ± 2.7 mm (p < 0.001) and an overjet reduction of 2.0 ± 2.2 mm (p = 0.005). There were no statistically significant correlations found between the age at T1, age at treatment start and age at T2 and the changes identified in the cephalometric variables (T2-T1). CONCLUSION: The HH-Mentoplate Class III treatment protocol induced a mean Wits improvement of 3.4 mm in the maxillary and mandibular sagittal base relationship at the functional occlusal level. This was primarily achieved by sagittal maxillary skeletal protraction with negligible effects on the mandible, facial vertical dimension and the incisor angulations. A controlled clinical study with larger sample sizes and longer follow-up times is needed.

Orthodontic mini-implant stability at different insertion depths : Sensitivity of three stability measurement methods.

OBJECTIVES: The purpose of this work was to evaluate the influence of insertion depth on the stability of orthodontic mini-implants. Sensitivity of three different methods to measure implant stability based on differences in insertion depth were determined. METHODS: A total of 82 mini-implants (2 × 9 mm) were inserted into pelvic bone of Swabian Hall pigs. Each implant was inserted stepwise to depths of 4, 5, 6, 7, and 8 mm. At each of these depths, three different methods were used to measure implant stability, including maximum insertion torque (MIT), resonance frequency analysis (RFA), and Periotest(®). Differences between the recorded values were statistically analyzed and the methods tested for correlations. RESULTS: Almost linear changes from each insertion depth were measured with the values of RFA [implant stability quotient (ISQ) values range from 1-100], which increased from 6.95 ± 2.85 ISQ at 4 mm to 34.63 ± 5.51 ISQ at 8 mm, and with those of Periotest(®) [periotest values (PTV) range from -8 to 50], which decreased from 13.24 ± 4.03 PTV to -2.89 ± 1.87 PTV. Both methods were found to record highly significant (p < 0.0001) changes for each additional millimeter of insertion depth. The MIT increased significantly (p < 0.0001) from 153.67 ± 69.32 Nmm to 261 ± 103.73 Nmm between 4 and 5 mm of insertion depth but no further significant changes were observed as the implants were driven deeper. The RFA and Periotest(®) values were highly correlated (r = -0.907). CONCLUSIONS: Mini-implant stability varies significantly with insertion depth. The RFA and the Periotest(®) yielded a linear relationship between stability and insertion depth. MIT does not appear to be an adequate method to determine implant stability based on insertion depth.

Three dimensional anatomical exploration of the anterior hard palate at the level of the third ruga for the placement of mini-implants--a cone-beam CT study.

AIM: The aim of this retrospective investigation was to measure vertical bone thickness on the hard palate, determine areas with adequate bone for the insertion of orthodontic mini-implants (MIs), and provide clinical guidelines for identification of those areas. MATERIALS AND METHODS: Pre-treatment records of 1007 patients were reviewed by a single examiner. A total of 125 records fulfilled the inclusion criteria and were further investigated. Bone measurements were performed on cone-beam computed tomography scans, at a 90° angle to the bone surface, on 28 predetermined and standardized points on the hard palate. Bone thickness at various areas was associated to clinically identifiable areas on the hard palate by means of pre-treatment plaster models. RESULTS: Bone thickness ranged between 1.51 and 13.86 mm (total thickness) and 0.33 and 1.65 mm (cortical bone thickness), respectively. Bone thickness was highest in the anterior palate and decreased significantly towards more posterior areas. Plaster model analysis revealed that bone thickness was highest at the level of the third palatal ruga. CONCLUSIONS: The areas on the anterior palate with adequate bone thickness for successful insertion of orthodontic MI correspond to the region of the third palatal ruga. These results provide stable and clinically identifiable landmarks for the insertion of palatal MIs.

Effectiveness of maxillary protraction using a hybrid hyrax-facemask combination: a controlled clinical study.

OBJECTIVE: To evaluate the treatment effects of a hybrid hyrax-facemask (FM) combination in growing Class III patients. MATERIAL AND METHODS: A sample of 16 prepubertal patients (mean age, 9.5 ± 1.6 years) was investigated by means of pre- and posttreatment cephalograms. The treatment comprised rapid palatal expansion with a hybrid hyrax, a bone- and toothborne device. Simultaneously, maxillary protraction using an FM was performed. Mean treatment duration was 5.8 ± 1.6 months. The treatment group was compared with a matched control group of 16 untreated Class III subjects. Statistical comparisons were performed with the Mann-Whitney U-test. RESULTS: Significant improvement in skeletal sagittal values could be observed in the treatment group over controls: SNA: 2.4°, SNB: -1.7°, Co-Gn: -2.3 mm, Wits appraisal: 4.5 mm. Regarding vertical changes, maintenance of vertical growth was obtained as shown by a small nonsignificant increase of FMA and a small significant decrease of the Co-Go-Me angle. CONCLUSIONS: The hybrid hyrax-FM combination was found to be effective for orthopedic treatment in growing Class III patients in the short term. Favorable skeletal changes were observed both in the maxilla and in the mandible. No dentoalveolar compensations were found.

Stability of paramedian inserted palatal mini-implants at the initial healing period: a controlled clinical study.

OBJECTIVES: To assess the stability development of paramedian in comparison with midpalatal inserted mini-implants. MATERIAL AND METHODS: The test group consisted of 21 consecutively treated patients (13.7 ± 4.6 years). In each patient, a mini-implant was inserted paramedian in the anterior palate. Measurement of the insertion depth (ID), the maximum insertion torque (IT), and resonance frequency analysis (RFA) was performed at T0. RFA was repeated after 2 weeks (T1), 4 weeks (T2), and 6 weeks (T3). Correlations between measuring methods were calculated. RFA values at different times were tested for statistical differences. Data were compared with a group of patients who received median mini-implants of the same size. RESULTS: Initial stability was 14.06 ± 4.35 Ncm (IT) and 26.60 ± 5.28 ISQ (RFA) with an ID of 7.02 ± 1.04 mm. RFA and IT (r = 0.49, P = 0.023) showed a moderate significant correlation. Stability remained relatively constant, showing no significant differences between measurement times. Overall, RFA values decreased non-significantly by 2.25 ± 6.85 ISQ to a level of 24.35 ± 5.39 after 6 weeks. Comparing development of stability over time, it was found that significant differences were present at T0 and T1 (T0: -9.54 ISQ, P < 0.0001; T1: -3.69, P = 0.041). CONCLUSIONS: Paramedian inserted mini-implants provided sufficient stability. Showing a lower primary stability, RFA values did not differ from the control group from week four on, as no significant decrease in stability occurred at the initial healing period.

The Hybrid Hyrax Distalizer, a new all-in-one appliance for rapid palatal expansion, early class III treatment and upper molar distalization.

Growing class III patients with maxillary deficiency may be treated with a maxillary protraction facemask. Because the force generated by this appliance is applied to the teeth, the inevitable mesial migration of the dentition can result in anterior crowding, incisor proclination and a possible need for subsequent extraction therapy. The Hybrid Hyrax appliance, anchored on mini-implants in the anterior palate, can be used to overcome these side-effects during the facemask therapy. In some class III cases, there is also a need for subsequent distalization after the orthopaedic treatment. In this paper, clinical application of the Hybrid Hyrax Distalizer is described, facilitating both orthopaedic advancement of the maxilla and simultaneous orthodontic distalization of the maxillary molars.

Mini-implant stability at the initial healing period: a clinical pilot study.

OBJECTIVE: To evaluate the changes of mini-implant stability over the initial healing period in humans. MATERIAL AND METHODS: A sample of 19 consecutively treated patients (mean age 15.5 ± 7.3 years) was examined. In each patient, a mini-implant of a size of 2 × 9 mm was inserted into the anterior palate. Implant stability was assessed using resonance frequency analysis (RFA) immediately after insertion (T0), 2 weeks later (T1), 4 weeks later (T2), and 6 weeks later (T3). Insertion depth (ID) and the maximum insertion torque (IT) were measured. Data were tested for correlations between RFA, ID, and IT. All RFA values were tested for statistically significant differences between the different times. RESULTS: The mean ID was 7.5 ± 0.6 mm, and the mean IT was 16.8 ± 0.6 Ncm. A correlation was found between RFA and ID (r = .726, P < .0001), whereas no correlations between RFA and IT or between IT and ID were observed. From T0 to T1, the stability (36.1 ± 6.1 implant stability quotient [ISQ]) decreased nonsignificantly by 4.9 ± 6.1 ISQ values (P > .05). Between T1 and T2, the stability decreased highly significantly (P < .001) by 7.9 ± 5.9 ISQ values. From T2 on, RFA remained nearly unchanged (-1.7 ± 3.5 ISQ; P > .05). CONCLUSIONS: Mini-implant stability is subject to changes during the healing process. During weeks 3 and 4, a significant decrease of the stability was observed. After 4 weeks, the stability did not change significantly.

Systematic review of mini-implant displacement under orthodontic loading.

A growing number of studies have reported that mini-implants do not remain in exactly the same position during treatment, although they remain stable. The aim of this review was to collect data regarding primary displacement immediately straight after loading and secondary displacement over time. A systematic review was performed to investigate primary and secondary displacement. The amount and type of displacement were recorded. A total of 27 studies were included. Sixteen in vitro studies or studies using finite element analysis addressed primary displacement, and nine clinical studies and two animal studies addressed secondary displacement. Significant primary displacement was detected (6.4-24.4 µm) for relevant orthodontic forces (0.5-2.5 N). The mean secondary displacement ranged from 0 to 2.7 mm for entire mini-implants. The maximum values for each clinical study ranged from 1.0 to 4.1 mm for the head, 1.0 to 1.5 for the body and 1.0 to 1.92 mm for the tail part. The most frequent type of movement was controlled tipping or bodily movement. Primary displacement did not reach a clinically significant level. However, clinicians can expect relevant secondary displacement in the direction of force. Consequently, decentralized insertion within the inter-radicular space, away from force direction, might be favourable. More evidence is needed to provide quantitative recommendations.