Biomedical subjects

H Wehrbein

Publications and source records attributed to H Wehrbein.

At least 19 recordsLinked to original sources

PubMed2004

The effects of argon laser curing of a resin adhesive on bracket retention and enamel decalcification: a prospective clinical trial.

A prospective clinical trial was carried out to compare argon laser-curing of a traditional light-activated composite resin with conventional visible light-curing in terms of bond failure rate and incidence of enamel decalcification. Forty-five patients with a total of 742 metal brackets bonded to the upper and/or lower teeth in a modified split-mouth design participated in the study. The adhesive (Transbond XT) on the control teeth was cured by conventional visible light for 40 seconds, and the experimental teeth were exposed to 10 seconds of 250 mW argon laser irradiation. The patients were monitored for a period of 14 months. Intraoral photographic slides of the maxillary anterior teeth (212 in total) were taken at the beginning of treatment, after 12 months of treatment, following application of a plaque disclosing agent, and at the end of the observation period, following temporary debonding. Seven dentists used standardized rating systems to evaluate decalcification and plaque accumulation. The results of this study indicated that there were no significant differences between curing methods for the incidence of decalcification and plaque accumulation. However, the 10 second argon laser-curing method showed a statistically lower bond failure rate (2.4 per cent, P < 0.05) than the 40 second conventional visible light-curing method (5.7 per cent). It is concluded that the use of argon laser curing is superior to that of conventional light-curing with respect to bond failure and chairside time. However, the incidence of decalcification seems to be similar.

Adhesives↗

PubMed2001

Effects of orthodontic bands on marginal periodontal tissues. A histologic study on two human specimens.

Eight banded teeth on two human specimens (9 years, male; 19 years, female) were analyzed regarding the fit of the orthodontic bands and periodontal reactions. Five teeth (three molars, two premolars) were evaluated histologically in the horizontal plane and three (one molar, two premolars) in the sagittal plane using the micro-section method according to Donath. The fit of the bands varied in occluso-apical direction. The mean of marginal gaps was x = 0.23 mm in the occlusal, x = 0.03 mm in the equatorial, and x = 0.28 mm in the cervical area. In the equatorial area the thin cement layer was largely homogeneous, whereas porosities and microfissures were found predominantly in thicker cement layers. 85% of the occlusal and cervical band margins revealed cement defects and/or erosions which were colonized by felted, partially densely compacted microbial plaque. With regard to the periodontal effects, the signs of inflammation in the buccolingual gingival areas were markedly less severe due to the supramarginal position of the band margins. The interdental gingiva of all teeth presented the histological pattern of an established gingival lesion. Leukocyte infiltration and inflammatory exudation in the area of the transseptal fibers were exceptionally pronounced in one lower molar (band exposure time: 6 months). At this site the connective tissue attachment close to the cementoenamel junction was severely damaged on the mesial surface and the pocket epithelium proliferated towards the apex, meaning progression from established gingivitis to an initial periodontal lesion. The histologic findings on these human periodontal tissues confirm that the application and hygiene control of orthodontic bands have to be performed with great care to avoid permanent periodontal destruction.

Adult↗

PubMed2001

The mid-palatal suture in young adults. A radiological-histological investigation.

The aim of the present study was to analyse which histological-histomorphometric findings correspond to a radiologically diagnosed open (group I) or closed mid-palatal suture (group II) on occlusal radiographs. For this purpose, 30 radiological regions of interest (rROI) from specimens obtained from 10 subjects ranging in age from 18 to 38 years were evaluated, and compared with the suture morphology, mean sutural width, and degree of suture closure on stained sections (3/rROI). The results showed that whether or not a radiologically visible suture can be classified as 'open' depends predominantly on the main oronasal suture course in relation to the X-ray path, rather than on factors such as suture width and degree of obliteration. The mean sutural width was 231 microns in group I (n = 10 rROI) and 201 mu in group II (n = 20 rROI). The degree of obliteration in relation to the total oronasal suture length was 0.45 in group I and 1.30 per cent in group II. No significant differences were found between the corresponding parameters of the two groups. The term 'suture obliteration' or 'fusion' should be avoided if a suture is radiologically not visible, since in 11 of the 20 rROI in which the suture was not visible no obliteration was recorded morphometrically.

Adolescent↗

PubMed2001

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.

Adolescent↗

PubMed1999

Osteodynamics around orthodontically loaded short maxillary implants. An experimental pilot study.

The aim of this study was to investigate experimentally the effect of long-term orthodontic loading on the activity and location of osteodynamic changes around short titanium screw implants. For this purpose 6 maxillary premolars (1P1, 2P2, 3P3) were extracted from each of 2 foxhounds. After a 16-week healing period, 8 implants (4 per dog) were inserted in the edentulous areas. Simultaneously 2 implants (1 per dog) were positioned in the palatal suture. After an 8-week implant healing period the fixtures in the P1/P2 areas (n = 4) and the palate (n = 2) were loaded (test implants) by means of Sentalloy traction springs (approximately 2 N continuous force). The fixtures in the P2/P3 areas served as controls (n = 4). The osteodynamic changes during the force application period (26 weeks) were recorded with bone labeling fluorochromes. Histological evaluation revealed a tendency towards higher remodeling activity within the peri-implant bone (up to 500 microns from the implant surface) of the loaded compared with the unloaded sample. This higher activity was found on both sides facing the loading direction as well as on the opposite sides. Furthermore, within the bone adjacent to the marginal halves of the implants on the loading direction sides, this higher remodeling activity extended more than 1000 microns from the respective implant surfaces. The results suggest that long-term orthodontic loading of short maxillary implants may increase the remodeling activity within the peri-implant bone.

Animals↗

PubMed1999

Palatal implant anchorage reinforcement of posterior teeth: A prospective study.

A new orthodontic implant anchor system (Orthosystem) has been developed. This 1-piece device made from titanium consists of a screw-type endosseous section (lengths of 4 and 6 mm), a cylindrical transmucosal neck, and an abutment. Clamp caps with slots provide for attachment of square orthodontic wires (transpalatal bars) to the implant. The aim of the present prospective study was to evaluate the anchorage capacity of palatally inserted Orthosystem implants for anchorage reinforcement of posterior teeth. The sample consisted of 9 dental Class II patients (age 15 to 35 years) whose treatment plan included extraction of the maxillary first premolars. Each of the patients received 1 implant inserted into the center of the anterior palate. After a mean unloaded implant healing period of 3 months, transpalatal bars were inserted to connect the posterior teeth to the implant. Retraction of the canines and incisors was accomplished without the use of compliance-dependent headgear or Class II elastics. The degree of anchorage loss as well as the amount of canine and incisor retraction were evaluated by measurements of the casts and lateral cephalograms. The mean anchorage loss was 0.7 mm on the right side and 1.1 mm on the left (P <.05). The right and left canines were retracted 6.6 and 6.4 mm, respectively, and the mean overjet reduction was 6.2 mm. Because clinical assessment and postremoval histologic assessment both revealed stability of the short implant, the small anchorage loss was most likely from the deformation of the transpalatal bars by the orthodontic forces. Nevertheless, the treatment goal was achieved in all patients without the use of compliance-dependent auxiliaries. The clinical experience during and after implant insertion, active orthodontic treatment, retrieval of the implant, and subsequent wound healing are described.

Adolescent↗

PubMed1999

Palatal bone support for orthodontic implant anchorage--a clinical and radiological study.

When maximal anchorage is required during orthodontic treatment, additional aids are often needed to support the anchoring teeth. While intra-oral aids may be limited in their anchorage potential, extra-oral anchoring aids are often rejected by the patients. Endosseous implants may therefore be a valuable alternative for stable intra-oral anchorage. However, the possibility of using conventional implants is insufficient, e.g. for treating purely orthodontic patients with full dentition or where extraction sites are to be closed. Therefore, the mid-sagittal area of the palate is an alternative insertion site for the placement of implants for orthodontic anchorage. The limited bone height in this area inspired this comparison between bone thickness in the implantation site as verified by probing during the implantation of Straumann Ortho-system implants, and thickness as measured on the lateral cephalogram. The results suggest that vertical bone support is at least 2 mm higher than apparent on the cephalogram. In none of 12 patients was a perforation to the nasal cavity found. However, in five subjects the implant projected into the nasal cavity on the post-operative cephalogram. These results were supported by the study of the projections of palate and wires in wire-marked skulls where the wires were placed bilaterally on the nasal floor and on the nasal crest. It is therefore concluded that the mid-sagittal area of the palate lends sufficient bony support for the implantation of small implants (4-6 mm endosseous length, diameter 3.3 mm).

Adolescent↗

PubMed1998

Bone-to-implant contact of orthodontic implants in humans subjected to horizontal loading.

Implant-based anchorage in orthodontics is increasingly obtaining significance. In this study, implants were temporarily inserted into the mid-palatal and the mandibular retromolar areas in humans for orthodontic anchorage. Histological analysis of the implant-bone interface was performed following the retrieval of implants which were subjected to prolonged oblique orthodontic loading. The results of the histomorphometric evaluation indicated that all the implants serving for orthodontic anchorage were well integrated into the bone despite the prolonged application of the orthodontic loading. Hence, it may be concluded that small-size, one-part transmucosal implants with a self-tapping thread and an SLA surface seemed to provide adequate anchorage for orthodontic therapy. Furthermore, the successful integration and the subsequent oblique loading of these orthodontic implants provide evidence that continuous forces in the order of magnitude of 2-6 N are compatible with the maintenance of osseointegration.

Adolescent↗

PubMed1998

Aspects of the use of endosseous palatal implants in orthodontic therapy.

Control of anchorage is one of the fundamental aspects in orthodontics and dentofacial orthopedics. Osseointegrated implants provide such an anchorage in a reliable fashion, as has been demonstrated in orthodontic use of dental implants inserted for prosthetic reasons. More recently, special implants have been introduced that serve as temporary anchorage in orthodontics. One example is the Straumann Orthosystem (Institut Straumann AG, Waldenburg, Switzerland), which is inserted in the midsagittal area of the palate. Owing to the reduced bone height available in the palate, only short implants should be considered; surface enlargement by texturing and the achievement of good primary stability are prerequisite for success. The use of a palatal implant provides a continuous stable anchorage for patients with compromised periodontal anchorage potential, as well as in cases in which compliance is not dependable or cases with esthetic considerations in which the use of extraoral anchorage aids or Class II elastics may be problematic. Minimal stress on the patient, combined with maximal anchorage, distinguishes this promising new treatment modality for the orthodontist cooperating with an oral surgeon. The treatment concept is well aligned with the emphasized need for integral treatment in dentistry, especially of the adult patient.

Adolescent↗

PubMed1997

Orthodontic anchorage capacity of short titanium screw implants in the maxilla. An experimental study in the dog.

The aim of this study was to investigate experimentally the effect of long term orthodontic loading on the stability as well as on the peri-implant bone findings of short titanium screw implants (Bonefit, submersion depth 6 mm, phi 4 mm) inserted in regions with reduced vertical bone height. For this purpose, 6 maxillary premolars (1P1, 2P2, 3P3) were extracted from each of 2 foxhounds and reduction of alveolar bone height was performed by osteotomy. After a 16-week healing period, 8 implants (4 per dog) were inserted in the edentulous areas. Simultaneously, 2 implants (1 per dog) were positioned in the palatal suture (one-stage surgery). After an 8-week implant healing period, the fixtures in the P1/P2 areas (n = 4) and the palate (n = 2) were loaded (test implants) by means of transpalatal bars running anteriorly, fixed on the implants in the P1/P2 areas, and Sentalloy traction springs (approximately 2 N continuous force) inserted midsagittally between palatal implants and bars (force application period: 26 weeks). The fixtures in the P2/P3 areas served as controls (n = 4). Clinical measurements and histological evaluation revealed no implant dislocation of the loaded fixtures. These results suggest that short titanium screw implants inserted in the alveolar bone and palatal suture region retain their stability during long-term orthodontic loading, even following a relatively short unloaded implant healing period. Furthermore, it seems that long-term orthodontic loading may induce marginal bone apposition adjacent to the implants.

Alveolar Process↗

PubMed1997

Orthodontic retraction into recent and healed extraction sites. A histologic study.

The aim of this experimental study was to assess the advantages of an early or delayed treatment start after tooth extraction on the basis of hard-tissue findings (density, maturity, osteodynamics) and of soft-tissue responses at the extraction site. Following bilateral extraction of the second incisors, reciprocal space closure was initiated in 3 foxhounds (age: 3.5 years): group 1 (6 teeth) 12 weeks after extraction, group 2 (6 teeth) immediately after extraction. After an 8-week bodily tooth movement period and a 2-month retention period, evaluation was undertaken on the basis of clinical/radiologic and histologic criteria (sequential polychromatic bone marking, light microscopy). Histologic analysis yielded the following findings in group 1 (delayed tooth movement): low bone density at the extraction site with more mature lamellar bone, pronounced horizontal atrophy of the alveolar process with periosteal bone apposition in direction of tooth movement, increased tendency towards gingival invagination. The findings in group 2 were characterized by: higher bone density with less maturity (bundle bone) at the extraction site, broader alveolar process, reduced tendency towards gingival invagination. No qualitative difference between the 2 groups was found with respect to root resorption. The histologic findings therefore indicate that orthodontic retraction into extraction sites should be initiated at an early stage.

Animals↗

PubMed1996

The Orthosystem--a new implant system for orthodontic anchorage in the palate.

The present report describes the design and first clinical experiences of a newly developed endosseous orthodontic implant anchor system (Orthosystem, Institut Straumann, Waldenburg, Switzerland) for palatal anchorage. The 1-piece fixture made of titanium consists of a screw-type endosseous implant body (sandblasted, acid-etched, diameter 3.3 mm, lengths: 4 and 6 mm), a cylindrical polished transmucosal neck and an abutment. Clamp-caps provide attachment of square commercially available orthodontic wires (0.032 x 0.032 inch, SS) to the abutment (transpalatal bars). In a pilot study 1 fixture (implant body length: 6 mm) was inserted into the midsagittal anterior palatal region in each of 6 adult patients with Angle class II malocclusion (distocclusion 7 to 8 mm, overjet: approximately 9 mm). The treatment plan included extraction of the first maxillary premolars and retraction of the anterior teeth based on maximum anchorage of the posterior teeth without using compliance-dependent anchorage aids (headgear, class II elastics). Due to the design of the fixture only 1 simple surgical procedure was required for insertion (nonsubmerged method, 1-stage surgery). Accordingly the need for surgical exposure of the abutment for connection and wire insertion was eliminated. Thus, inconvenience to patients was reduced to a minimum. The patients are now at varying active treatment stages. The course of treatment of the most advanced case is described. Evaluation of the clinical and radiological findings after 12 months of treatment (3 months implant healing, 9 months active orthodontic treatment which is equal to the implant loading period) revealed no implant mobility/dislocation, favourable peri-implant soft tissue conditions, no marked mesial movement (approximately 0.5 mm) of the implant/transpalatal bar supported posterior teeth, and 8 mm retraction of the anterior teeth. Retrieval of the fixture and post-operative wound healing were uncomplicated. In the treatment of this case, no compliance-dependent extraoral anchorage was used, and the well aligned mandibular dentition was not bonded provide anchorage support (class II elastics).

Adolescent↗

PubMed1996

Distal movement of premolars to provide posterior abutments for missing molars.

In 24 patients with missing molar teeth in the upper and/or in the lower jaw, 32 premolars were distalized. The mean orthodontic distalizing distance was 9.4 mm (SD 2.6). After distalization all these teeth served as posterior abutments for fixed restorations. The investigation period ranged between 2.5 to 14.1 years, average 9.6 years (SD 3.2). The clinical examination criteria were sensitivity, mobility, probing depth, sulcus bleeding index; the radiologic criteria were root resorption (lateral and apical) marginal bone level and axial position. None of the 32 premolar abutments were lost during investigation period. All the teeth maintained their vitality. The measured probing depths and sulcus bleeding indices were low. Of the teeth tested 40.6% revealed localized lateral root resorption on the pressure side; the average postorthodontic depth of root resorption was 0.7 mm (SD 0.3), and the length 2.3 mm (SD 0.6). The follow-up examination revealed a partial repair of the lateral root lesions. The extent of apical root resorption amounted to 0.9 mm (SD 1.1). The marginal bone level showed a bone loss of 0.5 mm mesially and 0.2 mm distally. The findings confirm that the distalized premolar functioning as a posterior bridge abutment represents a prognostically favorable alternative to an implant.

Adolescent↗

PubMed1996

Mandibular incisors, alveolar bone, and symphysis after orthodontic treatment. A retrospective study.

The mandible of a deceased 19-year-old young woman who had been treated with an edgewise appliance was removed during autopsy. The overall tooth movements during the 19 months of treatment were reconstructed (treatment documents) and compared with the macroscopic, radiologic, and micromorphologic findings of the incisor/alveolar bone/symphysis complex of the dry mandible. The initial lateral cephalogram revealed an extremely narrow and high symphysis, with an incisor position straight above the thin bone. During treatment, the incisors had been moved to lingual (lingual root torque) and derotated. Morphologic evaluation of the dry mandible revealed lingual (oral) aspects of the roots reaching some millimeters out of the lingual alveolar bone and largely without cortical plate covering. Lateral dental contact radiographs of any bone/incisor segment showed the sagittal alveolar bone width to be smaller than the labiolingual (orobuccal) diameter of the incisor roots. A comparison of the approximate pretherapeutic alveolar bone height, which was assessed by measuring the distance from the cementoenamel junction to the most coronal margin of any root resorption in scanning electron microscopy, with that of the specimen showed a calculated bone loss on the lingual aspect extending from 2.3 to 6.9 mm. On the labial (buccal) aspect, bone loss was far less pronounced. These results suggest that in the case of a narrow and high symphysis, pronounced sagittal incisor movements and derotation during routine orthodontic treatment with a fixed appliance may be critical and lead to progressive bone loss of lingual and labial cortical plates.

Adult↗

PubMed1996

The use of palatal implants for orthodontic anchorage. Design and clinical application of the orthosystem.

This paper presents the Orthosystem (Institute Straumann, Waldenburg/ Switzerland), a new endosseous orthodontic implant anchor system for palatal anchorage. The Orthosystem may replace compliance dependent extraoral anchoring aids for orthodontics and makes a bonding of well aligned mandibular dentition and it's use with class II elastics unnecessary. The fixture is designed for a one-stage application. It consists of an implant of pure titanium with a surface-treated, screw-shaped endosseous part of 3.3 mm diameter and lengths of 4 and 6 mm. Above the polished transmucosal neck follows as abutment where transpalatal arches made of rigid orthodontic wires (0.032 x 0.032 inch) are fixed by means of a clamp-cap. 6 patients with an angle class II malocclusion were implanted with the 6 mm fixture in the proximal midsagittal region of the palate during a pilot study. The treatment goal was extraction of the first maxillary premolars with subsequent retraction of the frontal dentition under maximal anchorage of the lateral teeth. For the implantation a simple surgical procedure of 10 min length was required while no further invasive action are needed until explantation. This way the strain on the patients was reduced to a minimum. They are now at varying stages of active treatment and the most advanced case is demonstrated here. The clinical and radiological findings after 12 months of treatment comprising 3 months of healing revealed no implant mobility or dislocation, favourable periimplant soft tissue conditions, and no marked mesial movement of the implant supported teeth. The frontal dentition was retracted by 8 mm with space closure occurring in a relatively short treatment period.

Adolescent↗

PubMed1996

Biodegradable implants for orthodontic anchorage. A preliminary biomechanical study.

The use of endosseous implants as temporary orthodontic anchoring elements has good results in many clinical applications. The development of a new orthodontic implant anchorage system comprising an implant produced of biodegradable polylactide with a metal superstructure is described. The presented bioresorbable implant anchor for orthodontics system (BIOS) implant is designed to provide orthodontic anchoring functions in adolescents and adult patients, and to then be resorbed without a foreign body reaction or signs of clinical inflammation. Shear strength and maximum vertical strength have been measured in biomechanical in vitro tests. BIOS fixtures can be loaded with horizontal shearing forces of 50 N with a mean deflection of 0.26 +/- 0.13 mm and mean vertical removal forces of 155 +/- 80 N. Clinical studies are currently being undertaken to evaluate clinical practicability and biocompatibility of the BIOS implants.

Adolescent↗

PubMed1995

[Findings in the panoramic tomogram in orthodontic patients with functional disorders].

In our study of 107 patients, for whom data derived from clinical functional analysis, axiography and, in part magnet resonance imaging, were present, we were able to show that in routine orthodontic diagnosis the use of panoramic X-ray in the normal course of a general examination of the mandibular joint can also provide important indications of the presence of cranio-mandibular disorders. The panoramic X-ray revealed that in patients with Angle class II and front deep and open bite there were significantly mor changes in the form of the condyles. A definite morphologic finding of a retracted fovea pterygoidea was found frequently in patients with anterior disk replacement with or without reduction. Lastly, the panoramic X-ray showed that a change in form of the condyles, with in some cases a serious arthrosis, occurs significantly most frequent in patients with anterior displacement without reduction.

Adolescent↗

PubMed1995

[The development of a resorbable implant system for orthodontic anchorage. The BIOS implant system. Bioresorbable implant anchor for orthodontic systems].

The use of endosseous implants as temporary orthodontic anchoring elements has proven itself to be efficacious in many clinical applications. If, however, an implant is inserted into the jaw solely to correct a malocclusion without being used subsequently for prosthetic purposes, secondary surgery is required to remove the anchoring implant. The development of an orthodontic implant anchor system consisting of an implant made of biodegradable polylactide with a metal abutment may offer a solution to this problem. On the basis of its good mechanical properties, the BIOS implant system (bioresorbable implant anchor for orthodontics system) presented here is designed to assume orthodontic anchoring functions as long as necessary and then be resorbed by hydrolysis without foreign body reactions. Shear strength and maximum vertical strength were measured in biomechanical in vitro tests in which BIOS fixtures can be loaded with horizontal shear forces of 50 N with a mean deflection of 0.26 mm and mean vertical pull-off forces of 155 N. In a clinical case report the application of the BIOS implant system during orthodontic tooth movement is here illustrated. In vitro and in vivo results obtained to date suggest that the BIOS implant system can be used as an orthodontic anchoring system up to the time of degradation.

Absorption↗