Manuel Nienkemper

Measurement of mini-implant stability using resonance frequency analysis.

OBJECTIVE To investigate whether resonance frequency analysis (RFA) is suitable to measure orthodontic mini-implant stability. Implant size significantly affects the level of resonance frequency. Regarding the operating mode of RFA, it has to be proven whether the resonance frequency of mini-implants in bone fits the range of frequency emitted by the Osstell ISQ device. MATERIAL AND METHODS For this purpose the SmartPegs in the Osstell ISQ device were modified to fit with the inner screw thread of orthodontic mini-implants, and 110 mini-implants were inserted into porcine pelvic bone. RFA was performed parallel and perpendicular to the run of superficial bone fibers. A suitability test, Periotest, was also performed in the same directions. Compacta thickness was measured using cone-beam computed tomography. Correlation tests and linear regression analysis were carried out between the three methods. RESULTS The RFA showed a mean Implant Stability Quotient value of 36.36 ± 2.67, and the Periotest mean value was -2.10 ± 1.17. The differences between the two directions of measurement were statistically significant (P > .001) for RFA and the Periotest. There was a high correlation between RFA and the Periotest (r  =  -0.90) and between RFA and compacta thickness (r  =  0.71). The comparison between the Periotest and compacta thickness showed a correlation coefficient of r  =  -0.64. CONCLUSION The present results suggest that RFA is feasible as a measurement method for orthodontic mini-implant stability. As a consequence, it could be used for clinical evaluation of current stability and allow stability-related loading of mini-implants to reduce the failure rate.

Maxillary protraction using a hybrid hyrax-facemask combination

BackgroundThe aim of this in study was the evaluation of treatment outcomes after using a hybrid hyrax-facemask combination in growing class III patients.MethodsTreatment of 16 children (mean age 9.5 ± 1.3 years) was investigated clinically and by means of pre- and post-treatment cephalograms. Changes in sagittal and vertical, and dental and skeletal values were evaluated and tested for statistically significant differences.ResultsAll mini-implants remained stable during treatment. Mean treatment duration was 5.8 ± 1.7 months. There was a significant improvement in skeletal sagittal values: SNA, +2.0°; SNB, -1.2°; ANB, +3.2°; WITS appraisal, +4.1 mm and overjet, +2.7 mm. No significant changes were found concerning vertical skeletal relationships and upper incisor inclination. In relation to A point, the upper first molars moved mesially about 0.4 mm (P = 0.134).ConclusionsThe hybrid hyrax-facemask combination seems to be effective for orthopaedic treatment in growing class III patients. Unwanted maxillary dental movements can be avoided due to stable skeletal anchorage.

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.

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.

Effects of wear time recording on the patient's compliance.

OBJECTIVE To assess the effect of wear-time recording on subjective and objective wear time. MATERIALS AND METHODS This study retrospectively examined a group of 18 patients and a control group of 14 patients at four appointments over 168 days. The patients were treated with removable appliances with embedded TheraMon-microsensors to be worn for 15 hours per day. The study group was not told about the microsensor until the first appointment after fitting of the appliance. At each appointment patients were asked about their subjective wear time and afterward were told about the objective wear time. The existence of the microsensor was revealed to the control group when the appliance was fitted. Objective wear time was also announced at every appointment. RESULTS Mean wear times did not significantly differ between groups at any appointment or regarding overall wear time. Highly significant differences between subjective and objective wear time were found when patients did not know that their wear time had been monitored. CONCLUSION Mean wear times assessed in this study concur with data of previous studies. Patients tend to overestimate their wear times but become more realistic once they know wear time is being monitored. Objective measurement of wear time allows a more realistic view of compliance by patient and orthodontist. Knowing that wear time is recorded does not necessarily increase the amount of time removable appliances are worn by the patient.

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.

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.

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.

Influence of time after extraction on the development of gingival invagination: study protocol for a multicenter pilot randomized controlled clinical trial

BackgroundGingival invaginations are a common side effect of orthodontic therapy involving tooth extraction and subsequent space closure. Consequences of gingival invaginations are a jeopardized stability of the space closure and hampered oral hygiene. In a retrospective study, the factor time until initiation of orthodontic space closure after tooth extraction has been identified as a potential risk factor for the development of gingival invaginations. The aim of this pilot study is to proof this hypothesis and to enable a caseload calculation for further clinical trials. The referring question is: is it possible to reduce the number of developing gingival invaginations by initiation of orthodontic space closure after tooth extraction at an early point of time?DesignThe intended pilot study is designed as a multicenter randomized controlled clinical trial, comparing the impact of two different time intervals from tooth extraction to initiation of orthodontic space closure on the development of gingival invaginations.Forty participants, men and women in the age range of 11 to 30 years with orthodontically related indication for tooth extraction in the lower jaw, will be randomized 1:1 in one of two treatment groups. In group A the orthodontic tooth movement into the extraction area will be initiated in a time interval 2 to 4 weeks after tooth extraction. In group B the tooth movement will be initiated in a time interval >12 weeks after extraction. A possible effect of these treatment modalities on the development of gingival invaginations will be documented at the moment of space closure or 10 months +/- 14 days after initiation of space closure respectively, by clinical documentation of the primary (reduced number of gingival invagination) and the secondary endpoint (reduction of the severity of gingival invaginations).Trial registrationUniversal Trial Number U1111-1132-6655; German Clinical Trials Register DRKS00004248

Utilisation combinée du Beneslider et d’appareils multi-bagues linguaux, mécaniques et procédure clinique

Over the last years, a tendency to prefer purely intra-oral appliances with minimal need for patient cooperation is noticed if upper molars should be distalized. Unfortunately, most of the conventional devices for non-compliance upper molar distalization produce unwanted side effects such as anchorage loss. To minimize or eliminate anchorage loss, mini-screws attracted a great attention in recent years because of minimal surgical invasiveness and low cost. Using the anterior palate as an insertion site, the failure rate is extremely low, there is no risk of root damage and the appliances are out of the path of tooth movement. Based on comprehensive clinical documentation, the rational and practical applications of the Beneslider in combination with lingual braces are presented. By this procedure, extractions in the upper arch and reactive forces in the lower arch resulting in a protrusion of the incisors can be avoided with an invisible treatment appliance.