Elena Krieger

Apical root resorption during orthodontic treatment with aligners? A retrospective radiometric study

IntroductionObjective of this study was to investigate the incidence and severity of apical root resorptions (ARR) during orthodontic treatment with aligners.Materials and methodsThe sample comprised 100 patients (17–75 years of age) with a class I occlusion and anterior crowding before treatment, treated exclusively with aligners (Invisalign®, Align Technologies, Santa Clara, CA, USA). The following teeth were assessed: upper and lower anterior teeth and first molars. Root and crown lengths of a total of 1600 teeth were measured twice in pre- and post-treatment panoramic radiographs. Afterwards, relative changes of the root length during treatment were calculated by a root-crown-ratio taking pre- and post-treatment root and crown lengths into consideration. A reduction of this ratio was considered as a shortening of the initial root length. Additionally, tooth movements of the front teeth were assessed by lateral cephalograms and the 3-dimensonal set up of each patient.ResultsAll patients had a reduction of the pre-treatment root length with a minimum of two teeth. On average 7.36 teeth per patient were affected. 54% of 1600 measured teeth showed no measurable root reduction. A reduction of >0%-10% of the pre-treatment root length was found in 27.75%, a distinct reduction of >10%-20% in 11.94%. 6.31% of all teeth were affected with a considerable reduction of >20%. We found no statistically significant correlation between relative root length changes and the individual tooth, gender, age or sagittal and vertical orthodontic tooth movement; except for extrusion of upper front teeth, which was considered as not clinical relevant due to the small amount of mean 4% ARR.ConclusionsThe present study is the first analyzing ARR in patients with a fully implemented orthodontic treatment with aligners (i.e. resolving anterior crowding). The variety was high and no clinical relevant influence factor could be detected. A minimum of two teeth with a root length reduction was found in every patient. On average, 7.36 teeth per patient were affected.

Current state of orthodontic patients under Bisphosphonate therapy

BackgroundBisphosphonates are a common medication for the prevention and therapy of osteoporosis, but are also applied for tumor diseases. They affect bone metabolism, and therefore also orthodontic treatments, but how it does has yet not been definitively clarified. Therefore, the aim of this research was to evaluate and demonstrate the reported effects and the current state of scientific research regarding orthodontic treatment and bisphosphonate medication exclusively in humans.Material and methodsA systematic research of the literature for selected keywords in the Medline database (Pubmed) as well as a manual search was conducted. The following search terms were used: ‘Bisphosphonate’ in combination with: orthodontic, orthodontic treatment, tooth movement.FindingsTo date, only nine reported patients (case reports/series) and one original article (retrospective cohort study) regarding orthodontic treatment under bisphosphonate medication in humans have been published. Decelerated tooth movement with increased side effects (especially in high-risk patients) and longer treatment duration was reported in some articles. Patients with initial spacing or extraction cases had a higher risk of incomplete space closure and poor root parallelism.ConclusionsOrthodontic tooth movement under bisphosphonate medication is possible, especially in low-risk patients (low dose and short period of intake). But the treatment is still not predictable, especially in high-risk patients. Therefore, the altered bone metabolism and higher extent of side effects should be considered in treatment planning, especially in extraction cases or high-risk patients. Regardless, longer treatment duration, decelerated tooth movement, and more side effects, e.g., incomplete space closure and poor root parallelism, should be expected, especially in extraction cases or space closure.

Interradicular trabecular bone density of the lateral maxilla for temporary anchorage devices – a histomorphometric study

ObjectiveTo analyze the interradicular trabecular bone density of the lateral maxilla regarding the insertion of temporary anchorage devices (TADs).Material and methodsThe material consisted of tissue blocks of autopsy material from 20 subjects (17 male, 3 female, 16 - 63y). The specimens comprised the dentated alveolar bone of the lateral maxilla. The interradicular areas (IRA) from canine to distally of the second molar (IRA 3–4, 4–5, 5–6, 6–7, 7d) were histomorphometrically measured with respect to the hard tissue fraction of the trabecular bone (HTFTB, %) and statistically analyzed.ResultsHistomorphometric measurements showed the following results: Mean HTFTB of IRA 3–4 was 44.08%, of IRA 4–5 31.07%, of IRA 5–6 33.96%, of IRA 6–7 36.33% and of IRA 7d 25.40%. Only the difference between the HTFTB of IRA 3–4 and the other IRAs was statistically significant (p < 0.05). Regarding the minimum and maximum HTFTB value of each IRA, there was a great amount of difference, especially for IRA 3–4: minimum HTFTB was 17.20% and maximum 67.03%.ConclusionApart from the IRA between canine and first premolar, the HTFTB in the IRAs of the lateral maxilla have to be classified as low or even moderate. IRA 3–4 should also be considered cautious regarding its minimum values. Thus, it seems that the interradicular trabecular bone density of the lateral maxilla is unfavorable to achieve a good primary stability of TADs.

One palatal implant for skeletal anchorage ??? frequency and range of indications

ObjectiveAim of this investigation was to analyze the frequency and range of indications of orthodontic treatments using one palatal implant for skeletal anchorage, in a time frame of four years.Material and methodsA sample was comprised by viewing retrospectively the patient collective of a specialized university clinic who started orthodontic treatment in the time frame 01/09-12/12. Inclusion criterion was the first application of a superstructure within the investigated period after successful insertion of a palatal implant (Ortho-System®, Straumann, Basel, Switzerland). Frequency and range of indications of the conducted skeletally anchored tooth movement were determined by analyzing the individual patient documentation such as medical records, radiographs and casts.ResultsFrom a total of 1350 patients who started orthodontic treatment in this period met 56 (=4.2%) the inclusion criterion. In 85.7% of this sample was sagittal orthodontic tooth movement conducted, most frequently mesialization of ≥1 tooth (44.6%). Vertical tooth movement was in 57.1% of the sample performed, mostly extrusion of ≥1 tooth (34%). In 33.9% of the sample was ≥1 displaced tooth orthodontically relocated. One or two upper incisors were in 16.1% of the sample permanently replaced by the superstructure, all but one even after orthodontic treatment. In 66.1% of all cases were multi-functional anchorage challenges performed.Conclusion4.2 % of all treated patients within the investigated period required orthodontic treatment with skeletal anchorage (palatal implant), mainly for performing sagittal tooth movement (mesialization). The palatal implant was primarily used for multi-functional anchorage purposes, including skeletally anchored treatment in the mandible.