Effects of Class II treatment with a banded Herbst appliance on root lengths in the posterior dentition.

INTRODUCTION: The aim of this study was a retrospective analysis of posterior teeth in 20 adolescents and young adults with Angle Class II Division 1 malocclusion treated with a banded Herbst appliance to check for inhibited root development and apical root resorption. METHODS: Panoramic radiographs were taken of every patient at the beginning and after the completion of functional orthopedic treatment. The magnification of the area of the posterior teeth was determined individually for every radiograph. Then the vestibular lengths of the molars and premolars were assessed metrically. To assess root-length changes, the difference between the lengths of the teeth before and after treatment was calculated. RESULTS: After treatment with a banded Herbst appliance, tooth length generally increased in the area of the anchorage. But there was a tendency toward root-length decrease in teeth immediately adjacent to the Herbst fittings in the vestibular roots of both the maxillary first molars (distovestibular, -0.02 ± 2.31 mm; mesiovestibular, -0.06 ± 2.05 mm) and the mandibular first premolars (-0.46 ± 3.53 mm). CONCLUSIONS: The banded Herbst appliance might deliver unphysiologic forces to immediate anchor teeth, thereby exposing these to a higher risk of root resorption than in other teeth incorporated into the anchorage either directly via bands or indirectly via occlusal or approximal contacts. Looking at uncompromised root morphology in the area of the anchorage, we believe that early treatment with fixed functional appliances can be predicted to yield better outcomes than late treatment because of the higher biologic tolerance expressed by teeth with an apical latency.

Open or submerged healing of implants with platform switching: a randomized, controlled clinical trial.

AIM: The temporal pattern of bone-level alterations in conventionally restored implants is dependent upon healing mode (open or submerged). This study examined the influence of healing on marginal bone levels at implants with a medium-rough surface including the implant collar and a clearance-fit implant-abutment connection restored according to a platform-switching concept. MATERIAL AND METHODS: Two implants were placed in the posterior mandible of 21 test subjects, randomly assigned to open (OH) or submerged (SH) healing. Standardized radiographs were obtained after implant surgery, before re-entry, after crown mounting, 1 and 2 years after implant surgery, and evaluated for implant-bone-level alterations (ΔIBL). Bacterial samples of the implants' inner cavities were analysed by cultivation. STATISTICS: Brunner-Langer Model, equivalence testings by Wilcoxon's (equivalence range ±0.4mm). RESULTS: After 2 years, ΔIBL were -0.47±0.46mm (OH) and -0.54±0.38mm (SH). At the 1-year follow-up, all implants were contaminated with bacteria. ΔIBL (p<0.001) and the amount of bacterial contamination (p<0.001) significantly depended on time, but not on healing mode. ΔIBL of OH and SH were equivalent at all time points (all p0.044). CONCLUSIONS: Platform-switched implants showed very limited peri-implant bone-level alterations. The healing-mode neither affected the total amount nor the temporal patterns of ΔIBL. Thus, the results for the tested implants with a non-rigid implant-abutment connection were similar to results reported previously for implants with a rigid implant-abutment connection.

Effects of conventional anchorage on premolar root development during treatment with a pendulum appliance.

OBJECTIVE: By metrically analyzing orthopantomograms, we aimed in this study to retrospectively investigate whether maxillary premolars used as anchoring teeth during molar distalization with pendulum appliances would reveal inhibited root development. PATIENTS AND METHODS: The upper molars were distalized with a modified pendulum appliance (Pendulum K) in 36 adolescents (14 males, 22 females, mean age 12.3 years). Mean treatment period was 19.5 weeks. Orthopantomograms of each patient were taken at the start (time point T1) and after completion of molar distalization (time point T2). The enlargement of the posterior region was ascertained individually quadrant by quadrant for each radiograph, followed by measurement of the vestibular tooth lengths of the premolars whose root development was for the most part not yet complete. To assess further root development in the premolar region, the differences were calculated between tooth lengths at the start and end of treatment. RESULTS: During treatment with the pendulum appliance a general increase in tooth lengths in the anchorage region was observed (1.37 +/- 1.70 mm, p<0.0001). Differentiated by dental age, we noted increases in tooth lengths of patients with second molars in the budding stage (patient group PG 1: 0.93 +/- 1.37 mm, p<0.0001) as well as of patients with fully-erupted second molars (patient group PG 2: 1.81 +/- 1.88 mm, p<0.0001). Both groups demonstrated greater increases in the second premolars than the first premolars; the increases group-wise were larger in PG 2 than PG 1. However, both the group comparison (PG 1 versus PG 2) and the side comparison (right versus left) (differentiated into first and second molars) showed no statistically relevant differences. Visual assessment of the radiographs revealed no evidence of treatment-related root deviations. CONCLUSION: A highly complex system of forces acts on the anchoring teeth during molar distalization with the conventionally-anchored Pendulum K. However, the Pendulum K appliance's specific biomechanics make it possible to transfer the reactive forces and moments to the anchorage unit so that they remain within the physiological range, allowing uninhibited premolar root development. This also applies after completed eruption of the second molars, when the treatment period and hence duration of exposure to the active and reactive forces and moments arising during molar distalization are comparatively increased.

Effects of two different functional appliances on root development of posterior teeth: activator vs. bite-jumping appliance.

OBJECTIVE: The aim of this study was to investigate retrospectively the incidence of inhibited root development by metric analysis of orthopantomograms, based on examination of the posterior teeth of 40 children and adolescents with Angle Class II, Division 1 malocclusion who received two different removable functional appliances to treat the distal intermaxillary relationship. PATIENTS AND METHODS: The patients were divided into two groups of equal size according to the appliance they wore for treatment (activator, bite-jumping appliance). Orthopantomograms for each patient were available from the start (time point T1) and after completion of the functional treatment (time point T2). Each radiograph's enlargement factor in the posterior region was ascertained. The vestibular tooth lengths of the molars and premolars were then measured. To assess root length development, we determined the differences between tooth lengths at the start and after the end of the treatment. RESULTS: Functional treatment generally led to an increase in tooth lengths in the anchorage region. Direct comparison of the two removable appliances revealed significant differences (p = 0.0478) in how much longer the maxillary first premolars became: following treatment with the activator, the teeth lengths increased by a mean of 2.64 mm +/- 5.12 mm, whereas the mean increase in length after bite-jumping appliance therapy was 0.59 mm +/- 3.40 mm. CONCLUSIONS: As a result of treatment with removable functional appliances, we observed locally different trends in root length increase in the posterior region in late-mixed and young adult dentitions, hence at a stage when root development had not concluded. The roots became longer during treatment with both the activator and bite-jumping appliance, but the maxillary first premolars' root development varied widely. This may be because the bite-jumping appliance's anchorage is right on the dentition, and the forces thus exert an immediate effect on the anchorage unit, particularly in the immediate vicinity of the protrusive bars in the maxilla. This led to certain groups of teeth to fail to achieve their entire potential length.

Efficiency of a skeletonized distal jet appliance supported by miniscrew anchorage for noncompliance maxillary molar distalization.

INTRODUCTION: Conventional anchorage appliances rely exclusively on intraoral anchorage for noncompliance molar distalization. The partial coverage of the palate, in particular, often results in compromised oral hygiene. An innovative alternative combines a skeletonized distal jet appliance with 2 paramedian miniscrews for additional anchorage. The objectives of this study were to investigate the suitability of the skeletonized distal jet for translatory molar distalization and to check the quality of the supporting anchorage setup. METHODS: Two paramedian miniscrews (length, 8-9 mm; diameter, 1.6 mm) were placed into the anterior area of the palate in 10 patients. Skeletonized distal jet appliances fitted with composite to the first premolars and the collars of the miniscrews were used for bilateral molar distalization, and the coil springs were activated with a distalization force of 200 cN on each side. RESULTS: The study confirmed the suitability of the appliance for translatory molar distalization (3.92 +/- 0.53 mm) with slight mesial inward rotation (on average, 8.35 degrees +/- 7.66 degrees and 7.88 degrees +/- 5.50 degrees ). The forces acting reciprocally on the anchorage setup were largely absorbed by the anchorage unit involving 2 anchorage teeth and 2 miniscrews. Significant anchorage loss, in the form of first premolar mesialization of 0.72 +/- 0.78 mm, was found. CONCLUSIONS: The skeletonized distal jet appliance supported by additional miniscrew anchorage allows translatory molar distalization. Although the anchorage design combining 2 miniscrews at a paramedian location and the periodontium of 2 anchorage teeth does not offer the quality of stationary anchorage, it achieves greater molar distalization in total sagittal movement than conventional anchorage designs with an acrylic button.

Interleukin-1 polymorphisms in relation to external apical root resorption (EARR).

AIM: Recent papers have discussed genetic predisposition for root resorption. The aim of this study was to investigate this kind of relationship as dependent on the EARR phenotype. Alleles from IL-1A and IL-1B gene polymorphisms are discussed as genetically predisposing factors. MATERIAL AND METHODS: Orthopantomograms (OPG) exhibiting EARR (n = 96) were metrically and statistically analyzed for expression and were compared to a control group (n = 162). Additionally, the percentage of affected teeth per individual was determined. A subgroup of the EARR patient sample (n = 49) was assessed, based on blood analyses, for an association with genomic IL-1A (-889) and IL-1B (+3954) polymorphism. RESULTS: In the case of the IL-1A variation, a significant difference of genotype distribution was found between EARR patients and the control group: genotype 2-2 could be seen significantly more frequently in the EARR group. Furthermore, the extent of resorption grades seemed to be influenced by the genetic constitution. The genotype distribution of the IL-1B polymorphism was comparable to the distribution in the control sample. In particular, allele 1 of the IL-1B polymorphism, which has been described as being associated with family histories of EARR, was observed less frequently in the patient cohort than in the control group. CONCLUSIONS: The available data of the IL-1A polymorphism point to an association of the genotype 2-2 with EARR. As analyses of individual subgroups showed, with the increase in the extent of EARR there was a recognizable correlation with genotype 2-2. The genotype distribution of the IL-1B polymorphism in patients and control cohorts revealed no indication of a predisposition. Despite the low number of cases in the own cohort, the data collected revealed that the allele 1 of the IL-1B polymorphism in patients with sporadic EARR did not contribute to predisposition, in contrast to familial cases. The results are an initial basis for pre-orthodontic genetic EARR risk analyses.

Anchorage efficacy of palatally-inserted miniscrews in molar distalization with a periodontally/miniscrew-anchored distal jet.

AIM: As a clinical pilot study using the skeletonized, periodontally/miniscrew-anchored Distal Jet appliance, this study aimed to verify the positional stability of the palatally-inserted paramedian miniscrews when subjected to loading for several months, hence to assess the efficacy of the supporting anchorage design. MATERIAL AND METHOD: Sixteen miniscrews (8-9 mm in length, 1.6 mm in diameter, polished surface) were inserted in the anterior region of the palate at paramedian locations. Once they had been in place for 1 week, skeletonized Distal Jets for bilateral molar distalization were anchored to the first premolars and necks of the miniscrews using composite. The appliances' coil spring systems were activated to a distalization force of 200-240 cN. The miniscrews were processed histologically after minimally-invasive explantation. RESULTS: Forces acting reciprocally on the anchorage unit result in significant anchorage loss in the palatally-inserted titanium miniscrews used for added anchorage support: we observed ventral movement in the vicinity of the miniscrew heads of 0.95+/-0.82 mm (the mean; p = 0.005), and extrusion of 0.21+/-0.28 mm (p = 0.040). In the process they tipped 2.65 degrees +/-6.23 degrees in relation to the palatal plane and 2.15 degrees +/-5.76 degrees in relation to the anterior cranial base. We observed no evidence of direct screw-to-bone contact in any of the explanted miniscrews. CONCLUSIONS: Titanium miniscrews with a polished surface, 1.6 mm in diameter and 8-9 mm long, do not provide stationary anchorage in molar distalization with the periodontally/miniscrew-anchored Distal Jet. When subjected for several months to load from forces that act in reciprocity to the force systems occurring during molar distalization, they fail to remain completely stationary in position in the palatal locations in which they were inserted. However, the combined anchorage setup is sufficient, intraorally and regardless of patient compliance, to largely compensate for the mesially-acting forces that occur reciprocal to molar distalization.

Disc-condyle Relationships during Class II Treatment with the Functional Mandibular Advancer (FMA).

OBJECTIVE: The objective of this study was to verify the effects of treatment to correct Class II malocclusion with the Functional Mandibular Advancer (FMA) on the relative positions of the articular disc and mandibular condyle. In particular, we aimed to find out whether the disc-condyle relationship changed between baseline and post-treatment, in temporomandibular joints initially exhibiting a physiological relationship and alternatively, in temporomandibular joints initially presenting anterior displacement of the articular disc. PATIENTS AND METHODS: Treatment progress in 15 patients was monitored at defined points in time by manual structural analysis (MSA) and magnetic resonance (MR) imaging. The disc-condyle relationship was assessed by examining the parasagittal MR images made up of three slices each (lateral, central, medial) taken in habitual intercuspation and maximum-open mouth position. The MR images were metrically analyzed to determine the sagittal positional relationship of the articular disc and mandibular condyle using two methods on the central slices of the images taken in closed-mouth position. MSA was used in particular to determine the disc-condyle relationships and to metrically record the extent of active movement of the mandible during mouth opening, protrusion, laterotrusion, and retrusion. RESULTS: Comparison of baseline and post-treatment findings revealed that none of the joints exhibited a treatment-induced deterioration in the disc-condyle relationship, while the relationship improved in five joints. After categorization of the joints according to groups according to disc position, metric analysis of the MR images showed significantly-improved post-treatment disc positions in the joints that had initially exhibited anterior disc displacement. Post-treatment findings for maximum-open mouth position, protrusion, and laterotrusion corresponded to the baseline values recorded before bite-jumping, and the extent of maximum active retrusion increased significantly. CONCLUSIONS: Functional jaw orthopedics for correction of skeletal Class II with the rigid fixed FMA leads to side-effects reflected in the disc-condyle relationship in the temporomandibular joints: no adverse effects were observed in joints presenting an initial physiological disc-condyle relationship, whereas the disc position may improve in joints with initial partial or total anterior disc displacement. In comparison with the baseline findings, we observed no post-treatment restriction in the extent of maximum mouth opening, protrusion, and left and right laterotrusion. Maximum active retrusion increased due to the treatment. MR imaging and MSA only partly cover the same aspects of temporomandibular joint diagnostics.