Invisalign? treatment in the anterior region

OBJECTIVE: Based on our previous pilot study, the objective of this extended study was to compare (a) casts to their corresponding digital ClinCheck? models at baseline and (b) the tooth movement achieved at the end of aligner therapy (Invisalign?) to the predicted movement in the anterior region. MATERIALS AND METHODS: Pre- and post-treatment casts as well as initial and final ClinChecks? models of 50?patients (15-63?years of age) were analyzed. All patients were treated with Invisalign? (Align Technology, Santa Clara, CA, USA). Evaluated parameters were: upper/lower anterior arch length and intercanine distance, overjet, overbite, dental midline shift, and the irregularity index according to Little. The comparison achieved/predicted tooth movement was tested for equivalence [adjusted 98.57% confidence interval (-?1.00; +?1.00)]. RESULTS: Before treatment the anterior crowding, according to Little, was on average 5.39?mm (minimum 1.50?mm, maximum 14.50?mm) in the upper dentition and 5.96?mm (minimum 2.00?mm, maximum 11.50?mm) in the lower dentition. After treatment the values were reduced to 1.57 mm (minimum 0?mm, maximum 4.5?mm) in the maxilla and 0.82?mm (minimum 0?mm, maximum 2.50?mm) in the mandible. We found slight deviations between pretreatment casts and initialClinCheck? ranging on average from -0.08?mm (SD ±?0.29) for the overjet and up to -0.28?mm (SD ±?0.46) for the upper anterior arch length. The difference between achieved/predicted tooth movements ranged on average from 0.01?mm (SD ±?0.48) for the lower anterior arch length, up to 0.7?mm (SD ±?0.87) for the overbite. All parameters were significantly equivalent except for the overbite (-1.02; -?0.39). CONCLUSION: Performed with aligners (Invisalign?), the resolvement of the partly severe anterior crowding was successfully accomplished. Resolving lower anterior crowding by protrusion of the anterior teeth (i.e., enlargement of the anterior arch length) seems well predictable. The initial ClinCheck? models provided high accuracy compared to the initial casts. The achieved tooth movement was in concordance with the predicted movement for all parameters, except for the overbite.     

Influence of clodronate and compressive force on IL-1ß-stimulated human periodontal ligament fibroblasts

Objectives

The aim of this study was to investigate in vitro the effect of clodronate on interleukin-1ß (IL-1ß)–stimulated human periodontal ligament fibroblasts (HPdLFs) with the focus on inflammatory factors of orthodontic tooth movement with and without compressive force.

Materials and methods

HPdLFs were incubated with 5 μM clodronate and 10 ng/mL IL-1ß. After 48 h, cells were exposed to 3 h of compressive force using a centrifuge. The gene expression of cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), matrix metalloproteinase 8 (MMP-8), and the tissue inhibitor of MMP (TIMP-1) was analyzed using RT-PCR. Prostaglandin E2 (PGE-2), IL-6, and TIMP-1 protein syntheses were quantified via ELISA.

Results

Compressive force and IL-1ß induced an overexpression of COX-2 gene expression (61.8-fold; p < 0.05 compared with control), diminished by clodronate (41.1-fold; p < 0.05 compared with control). Clodronate slowed down the compression and IL-1ß induced IL-6 gene expression (161-fold vs. 85.6-fold; p < 0.05 compared with control). TNF-α was only slightly affected without statistical significance. Clodronate reduced IL-1ß-stimulated MMP-8 expression with and without compressive force. TIMP-1 on gene and protein level was downregulated in all groups. Analyzing the MMP-8/TIMP-1 ratio, the highest ratio was detected in IL-1ß-stimulated HPdLFs with compressive force (21.2-fold; p < 0.05 compared with control). Clodronate diminished IL-1ß-induced upregulation of MMP-8/TIMP-1 ratio with (11.5-fold; p < 0.05 compared with control) and without (12.5-fold; p < 0.05 compared with control) compressive force.

Conclusion

Our study demonstrates a slightly anti-inflammatory effect by clodronate under compressive force in vitro. Additionally, the periodontal remodeling presented by the MMP-8/TIMP-1 ratio seems to be diminished by clodronate.

Clinical relevance

Reduction of pro-inflammatory factors and reduction of periodontal remodeling might explain reduced orthodontic tooth movement under clodronate intake.

     

Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients

Objective: To evaluate the demographic, radiological and therapeutic parameters that influence the overall clinical performance of palatal implants subjected to orthodontic loading. Patients and methods: The data of all patients who had received an orthodontic palatal implant for skeletal anchorage between January 1998 and December 2007 were reviewed retrospectively. The primary endpoint was the implant loss. The following parameters were assessed by univariate (log‐rank test) and multivariate (Cox's regression) analysis: (a) age and gender, (b) vertical bone height along the prospective implant axis, (c) surgeon's experience and (d) implant type. Results: Two‐hundred and thirty‐nine palatal implants were inserted in patients aged between 10 and 65 years. In all, 11/239 (4.6%) implants were lost: nine during the healing phase and two under functional loading. On univariate analysis, “surgeon's experience” was associated with a better implant survival and vice versa (P=0.0005; log‐rank test). The significance of “surgeon's experience” was confirmed by Cox's regression analysis (P=0.001; Wald test). All other parameters had no impact on implant loss. Conclusions: The survival probability of palatal implants is not related to demographic and radiological parameters. Implant losses mainly occurred early in the healing phase of the palatal implant. According to our data, “surgeon's experience” is the cornerstone of palatal implant success.     

Dental compensation for moderate Class?III with vertical growth pattern by extraction of the lower second molars

Objectives

Analysis of the effects and side effects of treatment of patients with moderate skeletal Class?III and vertical growth pattern by means of extraction of the second molars in the lower jaw.

Patients and methods

A total of 20 patients with a mean age of 12.9 years were examined retrospectively. Inclusion criteria consisted of a Wits value of 0 to ?5, a posterior growth pattern of the mandible (Hasund analysis), an overjet of ?2 to 1?mm, and an overbite of 0 to ?3?mm. Treatment was performed using a straight-wire appliance. As part of the treatment, the lower second molars were extracted and Class?III elastics attached. Cephalograms and orthopantomograms taken before and after treatment were used for evaluation.

Results

Treatment resulted in a significant change in the mean overjet from 0.5?mm to 2.1?mm and the attainment of a positive mean overbite of ?1.0?mm to 0.9?mm. The occlusal plane rotated anteriorly from 18.8° to 13.7°. The skeletal parameters showed a change in the Wits value from ?3.3?mm to ?1.4?mm and an anterior mandibular rotation (ML-NSL 35.5° vs. 32.0°). The soft tissues revealed an increase in the distance between the lower lip and the ??esthetic line?? to the posterior (?2.0?mm vs. ?3.9?mm).

Conclusion

Dental compensation of moderate skeletal Class?III with a tendency to an anterior open bite with vertical growth pattern by extracting the lower second molars, combined with Class III elastics, resulted in an anterior rotation of the occlusal plane and mandible. Eighteen of 20 patients achieved a physiological overjet and positive overbite. A prerequisite for this therapy is the presence of lower wisdom teeth; a potential side effect is elongation of the upper second molars.     

Orthodontic treatment of patients medicated with bisphosphonates—a clinical case report

Introduction

Bisphosphonates (BP) are an established medication, e.g., for the prevention/therapy of osteoporosis. The effects of the changed bone metabolism for orthodontic treatments are unknown.

Case report

A 66-year-old woman underwent a total oral rehabilitation. The therapy included (1) tooth extractions, (2) periodontal treatment, (3) insertion of dental implants, (4) provisional implant restorations, (5) orthodontic treatment, and (6) definite implant restorations. The orthodontic tooth movements were in- and retrusion of the upper frontal teeth, intrusion of the lower front teeth, using the dental implants as skeletal anchorage. After implant insertion and one month before beginning the orthodontic treatment, osteoporosis was diagnosed in this patient and, without notification to our facility, BP treatment was initiated by her general practitioner (alendronate oral, 70 mg/week), with an overall duration of intake of 7 months. After 13 months, the orthodontic treatment was successfully accomplished; however enlarged periodontal gaps, sclerotic bone areas, and mild apical root resorptions of the upper frontal teeth were found in this patient.

Conclusion

Currently, there are no recommendations for orthodontic patients undergoing BP therapy. Orthodontic tooth movement in this low-risk patient with a short duration of intake and a low-dose BP medication was possible. Because of the reduced bone metabolism and the higher amount of side effects, the treatment should be performed with extremely light forces and frequent monitoring.     

Induction of IL-6 and MMP-8 in human periodontal fibroblasts by static tensile strain

Objectives

Mechanical loading is a potential activator of inflammation and able to stimulate factors for periodontal and alveolar bone destruction. Aim of this study was to investigate the inflammatory response and synthesis of proteinases by human periodontal ligament fibroblast (HPdLF) dependent on different strengths of static tensile strain (STS).

Materials and methods

HPdLFs were loaded with different STS strengths (1, 5, and 10 %) in vitro. Gene expressions of cyclooxygenase (COX)-2 and interleukin (IL)-6 were analyzed by quantitative real-time polymerase chain reaction. Production of IL-6, prostaglandin E₂ (PGE₂), matrix metalloproteinase (MMP)-8, and tissue inhibitors of matrix metalloproteinase (TIMP)-1 were measured by enzyme-linked immunosorbent assay. Receptor activator of nuclear factor-kappa ligand (RANKL) synthesis was detected by immunocytochemical staining.

Results

Ten percent STS led to an increased gene expression of IL-6 and COX-2 (34.4-fold) in HPdLF, and 1 and 5 % STS slightly reduced the gene expression of IL-6. Synthesis of IL-6 was significantly reduced by 1 % STS and stimulated by 10 % STS. Ten percent STS significantly induced PGE₂ production. RANKL was not detectable at any strength of STS. MMP-8 synthesis showed significantly higher values only at 10 % STS, but TIMP-1 was stimulated by 5 and 10 % STS, resulting into highest TIMP-1/MMP-8 ratio at 5 % STS.

Conclusions

High-strength STS is a potent inducer of periodontal inflammation and MMP-8, whereas low-strength STS shows an anti-inflammatory effect. Moderate-strength STS causes the highest TIMP-1/MMP-8 ratio, leading to appropriate conditions for reformation of the extracellular matrix.

Clinical relevance

Furthermore, this study points out that the strength of force plays a pivotal role to achieve orthodontic tooth movement without inducing periodontal inflammation and to activate extracellular matrix regeneration.     

Mesio-marginal findings at tilted molars. A histological-histomorphometric study

The aim of this study was to investigate the mesio-marginal findings at tilted molars (TM) by means of histological-histomorphometric evaluation. Eight lateral tooth bone segments with TM (six mandibular, two maxillary) from males aged 20-32 years were compared with those of eight samples with non-tilted molars (NTM) in males aged 18-35 years. In comparison with the NTM samples, the TM revealed a higher amount of supra- and subgingival plaque, a significantly higher total number of inflammatory cells (P < 0.05) and blood vessels (P < 0.05) in the connective tissue adjacent to the junctional epithelium, and a lower density and corono-apical width of gingival fibres. No significant differences (P > 0.05) were found between the mesio-marginal bone level of the TM (mean: 978 microns) and that of the NTM (mean: 1222 microns). In contrast, indications were found that TM may affect the disto-marginal bone level of the mesial tooth.     

Immediate versus conventional loading of palatal implants in humans: a first report of a multicenter RCT

This study aims to analyze the clinical performance of two loading concepts on second-generation palatal implants (Orthosystem, Straumann, Basel, Switzerland) in a prospective multicenter randomized controlled clinical trial. At the time of this interim analysis, 41 patients have been randomized on a 1:1 basis to one of two treatment groups. Group 1 underwent conventional loading of palatal implants after a healing period of 12 weeks (gold standard) while group 2 underwent immediate implant loading within 1 week after implant insertion. We report initial results at 6 months after functional loading. The primary outcome parameter was implant success (no implant mobility, no implant loss). The implants in both groups were initially stable at the time of insertion, and all were eligible for randomization. Twenty-two patients (group 1) were subjected to conventional implant loading after 12 weeks while 19 patients (group 2) received immediate functional loading within the first week after insertion. Direct (e.g. distal jet appliances) as well as indirect forms of anchorage (conventional or modified transpalatal arch) were used. The magnitude of orthodontic forces ranged between 1 and 4 N for the immediate loading group and between 1 and 5 N for the conventional loading group. One implant in group 1 was lost during the healing phase. One dropout was registered in group 2. Thirty-nine implants were functionally loaded for over 6 months now. These preliminary data provide first evidence of the fact that immediate loading of palatal implants yields equivalent success rates as conventional loading to 4 N after 6 months.