Georgios Kanavakis

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.

Fully customized placement of orthodontic miniplates: a novel clinical technique

IntroductionThe initial stability and survival rate of orthodontic mini-implants are highly dependent on the amount of cortical bone at their insertion site. In areas with limited bone availability, mini-plates are preferred to provide effective skeletal anchorage. The purpose of this paper was to present a new clinical technique for the insertion of mini-plates.MethodsIn order to apply this new technique, a cone-beam image of the insertion area is required. A software (Galaxy Sirona, Bensheim, Germany) is used to construct a three-dimensional image of the scanned area and to virtually determine the exact location of the mini-plate as well as the position of the fixation screws. A stereolithographic model (STL) is then created by means of a three-dimensional scanner.Prior to its surgical insertion, the bone plate is adapted to the stereo-lithographic model. Finally, a custom transfer jig is fabricated in order to assist with accurate placement of the mini-plate intra-operatively.ResultsThe presented technique minimizes intra-operative decision making, because the final position of the bone plate is determined pre-surgically. This significantly reduces the duration of the surgical procedure and improves its outcome.ConclusionsA novel method for surgical placement of orthodontic mini-plates is presented. The technique facilitates accurate adaptation of mini-plates and insertion of retaining surgical screws; thereby enabling clinicians to more confidently increase the use of bone plates, especially in anatomical areas where the success of non-osseointegrated mini-screws is less favorable.

The most distal palatal ruga for placement of orthodontic mini-implants

OBJECTIVE To evaluate the stability and bone availability of the most distal (third) palatal ruga, as an anatomical region for safe insertion of orthodontic mini-implants (OMIs) in the anterior palate. STUDY DESIGN Orthodontic records of 35 patients were analysed. Initial (T1) and final (T2) study models were bisected and the outline of the palatal contour was marked on the surface. Models were scanned and the palatal contours were superimposed on the palatal structures on the respective initial and final cephalometric images. Cephalometric measurements were used to assess vertical (3rdRug-PP, 2ndRug-PP, and 1stRug-PP), and oblique bone levels (3rdRug-U1, 2ndRug-U1, 1stRug-U1, and 3rdRug-U1(o)). Paired Students t-test was used to compare measurements between T1 and T2. RESULTS The position of the third palatal ruga remained stable during orthodontic treatment (Δ2ndRug-3rdRug P = 0.1mm; P = 0.61 and Δ1stRug-3rdRug P = 0.2mm; P = 0.39). Bone availability also remained adequate (3rdRug-U1T2 (o) = 9.9mm). CONCLUSION The third palatal ruga is a reliable clinical landmark to evaluate bone availability for the placement of OMIs in the anterior palate.

Prevalence of malocclusion traits and orthodontic treatment in a Finnish adult population.

Abstract Objective The aim of the study was to examine the prevalence of malocclusion traits and the extent of orthodontic treatment in a Finnish adult population. Materials and methods The study population comprised subjects (n = 1964) from the Northern Finland Birth Cohort 1966 living in the city of Oulu and within 100 km of it. A clinical oral and dental examination with registration of occlusion was carried out in 2012 in connection with a 46-year follow-up survey. Data on previous orthodontic treatment were collected based on a questionnaire. Results In the clinical examination, 39.5% of the subjects had at least one malocclusion trait. The most common malocclusion traits were lateral crossbite (17.9%), overbite ≥ 6 mm (11.7%) and overjet ≥ 6 mm (9.7%). Crossbite on the left premolars, negative overjet and increased overbite were found more frequently in men. The prevalence of malocclusion traits was at the same level in treated and untreated groups. Overall, 18.6% of the subjects had undergone orthodontic treatment. Women showed a significantly higher prevalence of orthodontic treatment. Conclusions The most common malocclusion trait in the present study was lateral crossbite. Significant male dominance in the prevalence of malocclusion was observed, which has not been reported earlier in Finland. Orthodontic treatment of malocclusion traits was more common among females in Northern Finland. This study indicates that orthodontic treatment provided in childhood was, on average, adequate in reducing malocclusion traits to the level observed in the general population.

Newly defined landmarks for a three-dimensionally based cephalometric analysis: A retrospective cone-beam computed tomography scan review

OBJECTIVES To identify two novel three-dimensional (3D) cephalometric landmarks and create a novel three-dimensionally based anteroposterior skeletal measurement that can be compared with traditional two-dimensional (2D) cephalometric measurements in patients with Class I and Class II skeletal patterns. MATERIALS AND METHODS Full head cone-beam computed tomography (CBCT) scans of 100 patients with all first molars in occlusion were obtained from a private practice. InvivoDental 3D (version 5.1.6, Anatomage, San Jose, Calif) was used to analyze the CBCT scans in the sagittal and axial planes to create new landmarks and a linear 3D analysis (M measurement) based on maxillary and mandibular centroids. Independent samples t-test was used to compare the mean M measurement to traditional 2D cephalometric measurements, ANB and APDI. Interexaminer and intraexaminer reliability were evaluated using 2D and 3D scatterplots. RESULTS The M measurement, ANB, and APDI could statistically differentiate between patients with Class I and Class II skeletal patterns (P < .001). The M measurement exhibited a correlation coefficient (r) of -0.79 and 0.88 with APDI and ANB, respectively. CONCLUSIONS The overall centroid landmarks and the M measurement combine 2D and 3D methods of imaging; the measurement itself can distinguish between patients with Class I and Class II skeletal patterns and can serve as a potential substitute for ANB and APDI. The new three-dimensionally based landmarks and measurements are reliable, and there is great potential for future use of 3D analyses for diagnosis and research.

The role of occlusal curvatures and maxillary arch dimensions in patients with signs and symptoms of temporomandibular disorders

OBJECTIVE To identify differences in occlusal curvatures and maxillary arch dimensions between subjects with signs and symptoms of temporomandibular disorders TMDs and asymptomatic subjects. MATERIALS AND METHODS One hundred subjects 78 female and 22 male who consented to participate in this research were examined for signs and symptoms of TMDs according to the guidelines of the Research Diagnostic Criteria for Temporomandibular Disorders RDCTMD. In addition, occlusal measurements were performed for all subjects on plaster models. All statistical analyses were performed with SPSS version 19. RESULTS Significant associations were revealed between the depth of the curve of Spee COS and temporomandibular joint TMJ sounds. Furthermore, maxillary arch width was negatively correlated to the steepness of the curve of Wilson. No differences were found between subjects with and without a history of orthodontic treatment. CONCLUSIONS Subjects with TMJ sounds tend to have a flatter COS compared to subjects without TMJ sounds.

Interlot variations of transition temperature range and force delivery in copper-nickel-titanium orthodontic wires

INTRODUCTION The manufacturing process for copper-nickel-titanium archwires is technique sensitive. The primary aim of this investigation was to examine the interlot consistency of the mechanical properties of copper-nickel-titanium wires from 2 manufacturers. METHODS Wires of 2 sizes (0.016 and 0.016 × 0.022 in) and 3 advertised austenite finish temperatures (27°C, 35°C, and 40°C) from 2 manufacturers were tested for transition temperature ranges and force delivery using differential scanning calorimetry and the 3-point bend test, respectively. Variations of these properties were analyzed for statistical significance by calculating the F statistic for equality of variances for transition temperature and force delivery in each group of wires. All statistical analyses were performed at the 0.05 level of significance. RESULTS Statistically significant interlot variations in austenite finish were found for the 0.016 in/27°C (P = 0.041) and 0.016 × 0.022 in/35°C (P = 0.048) wire categories, and in austenite start for the 0.016 × 0.022 in/35°C wire category (P = 0.01). In addition, significant variations in force delivery were found between the 2 manufacturers for the 0.016 in/27°C (P = 0.002), 0.016 in/35.0°C (P = 0.049), and 0.016 × 0.022 in/35°C (P = 0.031) wires. CONCLUSIONS Orthodontic wires of the same material, dimension, and manufacturer but from different production lots do not always have similar mechanical properties. Clinicians should be aware that copper-nickel-titanium wires might not always deliver the expected force, even when they come from the same manufacturer, because of interlot variations in the performance of the material.

Comparison of shear bond strength and bonding time of a novel flash-free bonding system.

OBJECTIVE To evaluate the bonding time, shear bond strength (SBS), and adhesive residue index (ARI) of APC(TM) Flash-Free bonding system. MATERIALS AND METHODS Thirty-six extracted human maxillary premolars were randomly divided into three groups (12 per group) and used for this in vitro study: group 1, APC Flash-Free Adhesive Coated Appliance System; group 2, Clarity ADVANCED Ceramic Bracket pasted manually; group 3 (control group), 3M APC PLUS Adhesive prepasted brackets bonded with the extruded flash removed. Bonding time was measured using a stopwatch. Bond strength was measured using an Instron at a cross-head speed of 1 mm/min. The ARI was graded on a scale from 1 to 5. Repeated-measures analysis of variance and post hoc Tukey tests were used for statistical analysis. RESULTS It took significantly (P < .001) less time to bond in the APC Flash-Free Adhesive group (30.7 ± 3.3 seconds) compared with the control group (41.8 ± 4.0 seconds) and the manual group (39.2 ± 2.8 seconds). The APC Flash-Free Adhesive coated bracket had significantly (P < .001) greater SBS (13.7 ± 2.2 MPa) compared with the control group (10.8 ± 2.0 MPa) and the manual group (10.4 ± 1.4 MPa). The ARI was significantly (P < .001) greater with the APC Flash-Free Adhesive coated bracket compared with that of the other two groups. CONCLUSIONS Compared with other methods of bonding, the APC Flash-Free Adhesive Coated System can potentially reduce bonding time while increasing SBS.

Clinical outcomes of cases with missing lateral incisors treated with the ‘T’-Mesialslider

The objective of this article is to review the fabrication and activation procedures of the ‘T’-Mesialslider and to present the clinical outcomes in cases where canine substitution is the treatment of choice for missing maxillary lateral incisors. The ‘T’-Mesialslider allows for effective mesial translation of the canines and the posterior dentition, without significant loss of anterior anchorage and with good vertical control. Possible adverse effects of the appliance and clinical recommendations for their management are also discussed. In canine substitution cases with high anchorage demands, the ‘T’-Mesialslider provides an effective treatment option.

An active, skeletally anchored transpalatal appliance for derotation, distalization and vertical control of maxillary first molars

Objective The objective of this investigation was to evaluate treatment outcomes of the skeletally anchored ‘Frog’ appliance. Design A single-centre, retrospective study was performed. Setting Private orthodontic practice. Participants Patients who had undergone comprehensive orthodontic treatment with the skeletally anchored ‘Frog’ appliance. Methods 43 participants (20 males and 23 females) who had received treatment with the skeletally anchored ‘Frog’ appliance where included. In order to explore dentoalveolar and skeletal treatment outcomes, pre- (T1) and post- (T2) treatment measurements were performed on patients’ plaster models and cephalometric images. Comparisons between T1 and T2 were made by means of a Students t-test. All statistical analyses were conducted at the 0·05 level of statistical significance. Results Study model analysis revealed a statistically significant derotation of maxillary molars (μΔT2−T1 = 9·5°, P<0·001) as well as an increase in transverse arch dimensions at the end of treatment (μΔT2–T1 = 2·2 mm, P<0·001). Cephalometric changes included bodily distalization of maxillary molars (μΔ(T2–T1) = −1·9 mm, P<0·001), as well as noticeable angular displacement (μΔT2–T1 = 4·1°, P = 0·004). No significant anchorage loss was observed, as displayed by the limited change in maxillary incisor position (μΔ(T1–T2) = 0·2 mm, P = 0·45). In addition, excellent vertical control of the maxillary molars was achieved, with no change in the mandibular plane (ML/NSL) angle (μΔT2–T1 = 0·3°, P = 0·38). Conclusions The skeletal ‘Frog’ is effective in derotating and distalizing maxillary molars without anchorage loss and with excellent vertical control.