Biomedical subjects

P R Diedrich

Publications and source records attributed to P R Diedrich.

15 recordsLinked to original sources

PubMed2006

Effects of orthodontic treatment with fixed functional orthopaedic appliances on the condyle-fossa relationship in the temporomandibular joint: a magnetic resonance imaging study (Part I).

OBJECTIVES: This study aimed to verify the effects that corrective treatment for skeletal Class II malocclusions with fixed functional orthopaedic appliances has on the positions of the condyle within the glenoid fossa. METHODS: Orthodontic treatment progress was monitored in 20 patients by magnetic resonance imaging (MRI) at four defined points in time. Metric analysis of the temporomandibular joints was performed on the central slices of the images obtained in the closed-mouth position. To assess the positional relationship between condyle and fossa, the width of the joint spaces was measured. To compensate for individual variation of the condyle sizes, the Joint Space Index was calculated. The displacement of the condyle from the fossa was measured in the ventral and in the caudal dimension and the effective condyle reposition was computed. RESULTS: Upon adoption of the therapeutic position, the condyles were displaced from the centric position within the fossa toward caudal and ventral. At the end of treatment, they returned to their original position. No significant differences compared with initial findings were found in the width of the anterior or posterior joint spaces. CONCLUSION: For patients who received functional orthopaedic treatment for skeletal Class II correction with a fixed functional appliance, reduction to a physiological condyle-fossa relationship occurred bilaterally in the region of the joints. Our study suggests that the improved dental occlusion was not achieved at the price of a change to an unphysiological position in the temporomandibular joints.

Adolescent↗

PubMed2006

Effects of orthodontic treatment with fixed functional orthopaedic appliances on the disc-condyle relationship in the temporomandibular joint: a magnetic resonance imaging study (Part II).

OBJECTIVES: This study aimed to verify the effects that corrective treatment for skeletal Class II malocclusions with fixed functional orthopaedic appliances has on the relative positions of the articular disc and the mandibular condyle. METHODS: Orthodontic treatment progress was monitored in 20 patients by magnetic resonance imaging (MRI) at four defined points in time. Visual inspection of the temporomandibular joints (TMJs) was performed on three slices each (lateral, central, medial) of closed-mouth and maximum-open parasagittal MRI. Metric analysis was performed on the central slices of the images obtained in the closed-mouth position. To assess the positional relationship in the sagittal dimension between the articular disc and the mandibular condyle, both methods were used. RESULTS: The comparison of pre-treatment and post-treatment findings revealed in none of the joints that the disc-condyle relationship had been adversely affected as a consequence of the treatment. Rather, the outcome was an improved relationship in a total of eight joints. After groups of joints had been defined by disc position, metric analysis revealed a significantly improved positional relationship in those joints in which an anterior disc displacement had been found initially. CONCLUSION: Orthodontic treatment with a rigid, fixed functional appliance to correct skeletal distoclusion results in the following side effects on the disc-condyle relationship in the TMJ: the treatment does not have adverse effects on initially physiological disc-condyle relationships; in TMJs with initial partial or total anterior disc displacement, improved disc position can be achieved.

Adolescent↗

PubMed1997

Furcation involvement: comparison of dental radiographs and HR-CT-slices in human specimens.

In this in vitro study we compared dental radiographs and high resolution computed tomography (HR-CT) regarding identification and classification of the degree of horizontal and vertical furcation involvement. After removal of the soft tissue and metallic restorations of 18 dentate upper and lower jaws in the interradicular furcation region of 28 molars, bony defects of different dimensions were experimentally produced. The specimens were examined radiographically with standardized dental radiographs and 1.0 mm thick contiguous axial CT-scans. After identification of molars with artificial furcation involvement in the dental radiographs and axial CT-scans, the horizontal and vertical grades of furcation involvement were classified. Radiological identification and classification were compared with the macroscopic findings in the specimens. For quantitative histological-radiological comparison, corresponding microsections were prepared in the same plane as the axial CT-scans. In the dental radiographs the artificial furcation involvement in 6 of 28 (21%) molars was identified. In contrast, all 28 molars with involved furcations (100%) were identified in the axial CT-scans. The horizontal and vertical grades of furcation involvement were classified in the same way as the macroscopic findings, permitting comparison of histological sections and axial CT-scans. The HR-CT technique offers 3-dimensional assessment of the interradicular bone morphology in furcation involvement without overlying structures. The periradicular alveolar bone can be assessed on all sides of the roots. HR-CT scanning thus permits a high identification rate and classification of molars with involved furcations.

Alveolar Process↗

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

Guided tissue regeneration associated with orthodontic therapy.

Guided tissue regeneration (GTR) to enhance genuine new periodontal attachment may improve preorthodontic conditions for moving teeth into infrabony defects or for vertical movements of teeth with reduced bone support. The possible benefits of GTR for combined periodontal/orthodontic therapy are discussed and substantiated with preliminary experimental findings.

Alveolar Bone Loss↗

PubMed1996

Orthodontic procedures improving periodontal prognosis.

The wide range of interrelations between orthodontics and periodontology shows that besides the preventive significance in the mixed dentition, another focal point is the comprehensive rehabilitation of periodontally affected patients. With increasing experience in the field of adult orthodontics, setting therapeutic limits becomes increasingly difficult. It is impossible in principle to define in exact metric terms the probing depth or attachment loss up to which orthodontic tooth movement is feasible. The fact is rather that the orthodontic-periodontal treatment goal can be defined only after evaluation in each individual finding a number of different factors: esthetics, function, risks of orthodontic tooth movement, biomechanical considerations, and periodontal prognosis.

Adolescent↗

PubMed1995

Gingival invagination area after space closure: a histologic study.

The aim of this study was to show the micromorphologic findings (epithelium, connective tissue, bone) in a region of pronounced gingival invagination after space closure by analyzing a maxilla taken in autopsy from a 19-year-old woman who was orthodontically treated. The dental records were also at our disposal. The second left premolar was congenitally absent. This area displayed before therapeutic horizontal bone atrophy. For space closure, the first upper left molar was moved mesially with a fixed appliance. After space closure, pronounced gingival invagination was diagnosed. The lateral segments of the specimen were prepared histologically in the horizontal plane. The microscopic observations revealed deep epithelial proliferation, hyperkeratinization, and one isolated keratin pearl in the connective tissue. Irrespective of location, the broad connective tissue layer showed disparate characteristics. Cell-rich, loose connective tissue with low fiber density were dominant in the subepithelial layer. The epiperiosteal layer displayed multiple tough fibers, some running parallel, some with reticular meshing, permeated with many blood vessels. Very few inflammatory cells were detected in the soft tissue. The bone had been resorbed in the mesiopalatal area of the molar (tooth movement direction) apart from one small isolated bony islet. These observations suggest that inflammatory influences were unlikely for marginal bone loss mesiopalatal to the tooth.

Adult↗

PubMed1995

Human histologic tissue response after long-term orthodontic tooth movement.

UNLABELLED: The maxilla of a deceased 19-year-old young woman who had been treated with an edgewise appliance was removed during autopsy. The specimen was prepared histologically in the horizontal plane. The type of tooth movement was reconstructed by comparing the treatment documents at outset (photograph of dental cast, radiograph) with the photograph and radiographs of the specimen. This permitted the histological findings to be correlated to the type of tooth movement. RESULTS: the localization and extent of tissue changes at the roots depend on the type of tooth movement and the structure of the bone. In case of an atrophied alveolar bone in front of the tooth movement direction, a partial increase of osseous tissue may be induced by bone apposition in the subperiosteal layer. After tooth movement in the maxillary sinus region, however, bone resorption was found in the subperiosteal layer in front of the roots. The histologic findings are more pronounced than the radiographs would suggest. Histologically verified bony dehiscences or fenestrations in the facial or oral cortical plate could not be diagnosed by macroscopic inspection of the specimen.

Adult↗

PubMed1995

Assessment of alveolar bone loss with high resolution computed tomography.

In this in vitro study we compared high resolution computed tomography (HR-CT) with dental radiographs regarding the interpretation of horizontal and vertical alveolar bone loss. After removal of the soft tissue and metallic restorations of 20 dentate upper and lower jaw segments 40 infra-alveolar bony defects of different dimensions were experimentally produced. The specimens were examined radiographically with standardized dental radiographs and 1.0 mm thick contiguous axial CT-scans. On the specimens, radiographs and CT-scans the bone loss was measured between the cemento-enamel junction and the adjacent alveolar bone level of 472 mesial and distal tooth surfaces; the identification, classification and vertical depth of the infra-alveolar bony defects were also compared. An average underestimation of 0.6 mm of horizontal alveolar bone loss in the dental radiographs and an overestimation of 0.2 mm in CT-scanning was shown. No significant differences between the imaging accuracy of horizontal alveolar bone loss between dental radiographs and CT-scanning could be evaluated. In the dental radiographs 24 (60%) of the infra-alveolar bony defects could be identified and the vertical depth was underestimated by a mean of 2.2 mm. In comparison, all 40 (100%) infra-alveolar defects could be identified in the CT-scans and the vertical depth was underestimated by an average of 0.2 mm. The HR-CT-technique offers a three-dimensional interpretation of the alveolar morphology without overlying structures. This permits a high identification rate and classification of infra-alveolar bone loss according to the number of surrounding bone walls into one-, two or three-walled bony pockets.

Alveolar Bone Loss↗

PubMed1995

Assessment of the dentate alveolar process with high resolution computed tomography.

The present study was undertaken to determine quantitatively the accuracy of modern high-resolution computed tomography (HR-CT) in imaging periodontal defects in vitro by means of comparative radiological and histological studies. The soft tissue and metallic restorations were removed from four mandibular and maxillary jaw segments. Eighteen lingual and buccal defects of different dimensions were artificially created over the roots of the teeth. Dental radiographs and 1.0 mm contiguous axial and coronal HR-CT scans were obtained. Histological specimens were prepared in the same plane as the CT scans. A quantitative analysis of the periodontal regions on the CT scans was feasible when the alveolar bone was 0.5 mm thick. A visible periodontal ligament space was found to improve the reliability of the measurement of buccal or lingual bone plates up to 0.2 mm thick or of the artificial dehiscences. In the axial HR-CT scans, 70% of the artificial defects could be identified. and in the coronal scans, 50%. In contrast, none of the defects could be evaluated on conventional dental radiographs. It is concluded that HR-CT scanning could be useful in assessing buccal and lingual alveolar bone morphology and in diagnosing larger dehiscences.

Alveolar Bone Loss↗

PubMed1995

Three-dimensional imaging of craniomaxillofacial structures with a standard personal computer.

OBJECTIVE: To implement 3D-reconstruction of CT and MR data by a standard MS-DOS personal computer. METHODS: User-specific software has been developed for the 3D-reconstruction and quantitative evaluation of hard and soft tissues of the skull. RESULTS: The software displays a 3D-reconstruction and secondary reformatted vertical sections within 4-30 s on the monitor. The 3D-structures can be evaluated quantitatively with a freely-superimposable grid. Distances or angles between two landmarks can be measured directly. Various tools for the simulation of surgical treatment are available. CONCLUSIONS: Gross skeletal and soft-tissue malformations, topographical relations and the degree of asymmetry of severe maxillofacial deformities can be evaluated in more detail. Access to a readily available low-cost computer system for 3D-evaluation of the head will enable a larger number of clinicians to use 3D-methods in diagnosis and treatment planning. The off-line computing system permits a higher of flexibility independent of any computing centre.

Anatomy, Cross-Sectional↗

PubMed1994

Treatment prediction with three-dimensional computer tomographic skull models.

Orthodontic and surgical treatment planning in the conventional articulator is compared with three-dimensional computer tomographic (3D-CT) model surgery in an individually milled skull model. After computer tomography has been completed of the patient's skull that has a bimaxillary asymmetric disharmony, the data set is transferred to generate individually milled polyurethane foam models. The imprecisely delineated dental arches of the skull model are replaced by dental casts that allow the simulation of various orthodontic and surgical treatment procedures. Expected segment displacement, the best osteotomy lines, and the resulting skeletal and dental symmetry in relation to the orthodontic set up can be evaluated. Although the technique is both time-consuming and expensive compared with the traditional treatment planning through the articulator, we have included 3D-CT model surgery in our presurgical work-up of patients with severe dentofacial disharmonies. Especially in asymmetric cases, the individually milled skulls allow a higher precision of orthodontic and surgical treatment planning.

Centric Relation↗

PubMed1994

Periodontal conditions after facial root tipping and palatal root torque of incisors.

UNLABELLED: The maxilla of a deceased 19-year-old young woman who had been treated with a fixed appliance was removed during autopsy. The sagittal movements of the incisors could be reconstructed by using the treatment records, which were also at our disposal. The anterior segment of the specimen was prepared histologically in the sagittal plane and stained with toluidine blue. RESULTS: The tooth movements were executed in two phases: an uncontrolled tipping (root movement to vestibular) was followed by palatinal root torque. The histologic changes, induced by the palatinal root torque were (1) root resorption with apical slope from facioapical to orocoronal, and (2) pronounced subperiosteal bone apposition (palatinal) with partial protrusion of the cortical plate thinning toward coronal. No osseous perforations occurred. The extent and the localization of root resorptions were not verified in the orthoradial x-ray film of the specimen.

Adult↗

PubMed1994

B-mode ultrasound scanning of the tongue during swallowing.

The aim of the present study was to evaluate the ability of video-based dynamic B-mode ultrasound in differentiating normal from abnormal swallowing. Tongue position at rest and during the oral phase of swallowing was examined with a 5 MHz transducer placed under the chin in 60 subjects aged between 6 and 33 years. 40 patients with abnormal tongue movement or swallowing were compared with a control group of 20 adults with Angle Class I occlusion without any signs of dysfunctional tongue activity. The ultrasound sequences were videotaped and the movement of the tongue in swallowing a 2 ml water bolus analysed qualitatively. An abnormal swallowing pattern was demonstrated in 19 patients. Those with an Angle Class III malocclusion had the highest rate of abnormal swallowing. Video-based ultrasound scanning in the sagittal plane seems to be a useful screening method for the diagnosis of poor tongue coordination during swallowing, especially for the imaging of tongue thrust in children.

Adolescent↗

PubMed1993

[Computed tomographic imaging of the dentoalveolar-maxillary sinus lacuna of the dentate jaw].

A human bone segment of the lateral maxilla was scanned using high-resolution computed tomography (CT) in contiguous parallel axis slices in order to image the topographical relationship between upper molars and the maxillary sinus. The bone segment was dissected analogously in 1 mm thick sections. After exposing contact films from these jaw cuttings, microsections were made for histological interpretation. The radiological-histological comparison between the CT-scans, contact films and the histologic specimens revealed absolute differences of 0.2-0.6 mm. The high resolution CT allowed an interpretation of details located between teeth and bone when the minimum bone thickness was 0.5 mm or more. First experiences with the CT-technique in orthodontic patients were promising, especially for the differential diagnosis of the dentoalveolar maxillary sinus relation.

Adult↗