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Biomedical subjects

Winfried Harzer

Publications and source records attributed to Winfried Harzer.

14 recordsLinked to original sources
PubMed2006

Plane orientation for standardization in 3-dimensional cephalometric analysis with computerized tomography imaging.

INTRODUCTION: The purpose of this study was to propose certain landmarks and planes to standardize 3-dimensional image orientation. METHODS: Cone-beam computerized tomographic images were obtained from 10 adolescent patients and analyzed with AMIRA software (AMIRA, Mercury Computer Systems, Berlin, Germany). RESULTS: Four points (ELSA, right superior external auditory meatus, left superior external auditory meatus, and mid-dorsum foramen magnum) were located on each image. The axial-horizontal plane (x-y plane) was then determined by using both superior external auditory meatus and ELSA; the sagittal-vertical plane (z-y plane) was formed by ELSA and mid-dorsum foramen magnum perpendicular to the x-y plane. CONCLUSIONS: All points had high intrareliability and were adequate for standardizing the orientation of 3-dimensional images.

Adolescent↗
PubMed2006

Change of mRNA amount of myosin heavy chain in masseter muscle after orthognathic surgery of patients with malocclusion.

INTRODUCTION: Surgical correction of malocclusion changes the force to moment ratio of masticatory muscles inserting at the mandible caused by shortening, lengthening and rotation of the bone following osteotomy. During muscle adaptation the expression of mRNA for the myosin heavy chain (MyHC) of type I and type II fibres may be changed. MATERIAL AND METHODS: The adaptation of the masseter muscle was investigated at the mRNA level in 10 patients 6 months after orthognathic surgery in the mandible. The competitive polymerase chain reaction (cPCR) is a suitable method for quantification of MyHC mRNA. For application of this minimal invasive method an amount of 35 mg muscle tissue was sufficient. RESULTS: 6 month postoperatively there was a deficiency of about 87% of MyHC mRNA for fibre type I and II in both groups of patients. The deficiency in patients with mesial position of the mandible was higher but not significant different to patients with distal malocclusion. CONCLUSION: Patients should use the postoperative interval for training their masticatory muscles. This improves the stability of treatment result and prevents relapse.

Adult↗
PubMed2006

Orthodontic implants as anchorage appliances for unilateral mesialization: a case report.

Space closure from distal to mesial is one of the most difficult orthodontic tasks. Toothborne anchorage limits the scale of tooth movement. Extraoral or intraoral appliances are used especially for unilateral space closure. As an alternative to conventional mesialization appliances, osseointegrated implants may be used for maximum anchorage in orthodontic treatment. Temporary implants inserted in the palatal suture are most common in maxillary treatment. In the case presented, temporary implants were placed in the palatal bone of a 17-year-old male patient with hypodontia of the mandibular central incisors and second premolars and the maxillary left second premolar for mesialization of the molars. Slight irritations of the tongue were registered in the first 2 weeks of use of the palatal implant. There were no other effects during treatment.

Adolescent↗
PubMed2005

Myosin heavy chain protein and gene expression in the masseter muscle of adult patients with distal or mesial malocclusion.

The aim of this study was to determine the amount of myosin heavy chain (MyHC) proteins and MyHC mRNA in muscles of patients with different positions of the mandible. Ten adult patients for orthognathic surgery were divided into two groups: distal and mesial malocclusion. The mRNA expression of two MyHC isoforms of the anterior and posterior part of the right and left side of the human masseter muscle was analysed with a competitive RT-PCR assay. An exogenous template that includes oligonucleotide sequences specific for sarcomeric MyHC isoforms (1 and 2x) was constructed and utilized as competitor. Different isoforms of the MyHC protein were identified by Western blot analysis. In the total mRNA pool of the masseter muscle, the MyHC 1 mRNA level was 25.5 +/- 7.6% and the MyHC 2x mRNA was 2.5 +/- 1.2%. The anterior part of the masseter muscle from patients with distal occlusion contained more type 1 and 2x MyHC mRNA, as compared to patients with mesial occlusion (P < 0.05). No difference in the protein distribution was observed. The differences in mRNA expression may be caused by the enforced stress of the masticatory muscle in distal occlusion because of the disadvantageous pivot.

Adult↗
PubMed2004

Rapid maxillary expansion with palatal anchorage of the hyrax expansion screw--pilot study with case presentation.

BACKGROUND: Rapid maxillary expansion (RME) with the appliance fixed at the crowns of the first premolars and molars leads not only to transversal expansion but also to tipping of the anchorage teeth and a risk of increased tooth mobility as well as of root and bone resorptions. These disadvantages were to be avoided by fixing the transversal screw directly to the hard palate. MATERIAL AND METHOD: Following preliminary experimental work to determine the extent to which the hard palate could be loaded with orthodontic implants, two female patients were treated for extreme transverse maxillary deficiency using a Hyrax expansion screw fixed on one side with an implant with the following dimensions: length 4.0 mm, diameter 3.5 mm, abutment diameter 5.00 mm (EO implant, Straumann, Freiburg i. Br., Germany), and on the other side with a bone screw between the roots of the second premolars and the first molars. Presurgical osteotomy according to Glassmann was followed immediately by loading, i. e. by expansion through activation of the screw several times per day. Additional anterior guidance of the right and left maxilla was provided by crossed segmented archwires and a tension coil spring for space opening in the incisor region. After adequate expansion by 8.0 mm and correction of the position of the buccal teeth, the Hyrax expansion screw and the osteosynthesis screw were removed. The implant served as orthodontic anchorage for a molar-to-molar transpalatal bar aimed at preventing relapse. RESULTS AND CONCLUSIONS: The tooth axis inclination measured on cut sections of the plaster casts made at the beginning and end of treatment was largely without transversal discrepancies. Direct fixing of the transversal screw in the palatal arch prevents buccal tipping of the posterior teeth, especially in patients with a small apical base. Compared with other direct procedures involving osteosynthesis plates, this technique offers adequate guiding stability and is minimally invasive.

Adult↗
PubMed2004

Muscle influence on postnatal craniofacial development and diagnostics.

The postnatal craniofacial development is determined by exogenous and endogenous factors that may result in morphological and functional muscle changes and influence the dentoskeletal region in terms of a physiologic or dysgnathic development. Using functional appliances, efforts are made to treat skeletal malocclusions through targeted exercise and to prevent an undesirable development of the dentition and the craniofacial structures. However, the success of the treatment and the stability of the outcome are not always adequate. To illustrate the treatment processes, clinically relevant measures for diagnosing muscle function and morphology have been developed in recent years. Electromyographic investigations and bite-force measurements show an excessively high variability and the histologic examinations applied to date are restricted in their suitability for analysis of the human masticatory muscles. Animal experimental studies have meanwhile succeeded in simulating functional jaw orthopedics and in demonstrating muscle remodeling processes at the genetic level. Despite some invasiveness, the time and the small quantity of muscle tissue involved permit molecular biological measuring in the orofacial system.

Animals↗
PubMed2004

Prevalence of malocclusions in the early mixed dentition and orthodontic treatment need.

Early interceptive treatment for the elimination of factors inhibiting dental arch development and mandibular and maxillary growth is applied varyingly by orthodontists, possibly because there is little scientific evidence that such interventions are of actual benefit. The aim of this study was to determine specific factors for treatment need in the early mixed dentition period in order to obtain basic data to support early intervention. The study was part of a larger survey of 8768 children aged between 6 and 17 years. From this sample, 1975 children aged between 6 and 8 years were used to estimate the prevalence of malocclusions using the Index of Orthodontic Treatment Need (IOTN) during the early mixed dentition period. The results showed that deep overbite and overjet, both more than 3.5 mm, were the most frequent discrepancies, affecting 46.2 and 37.5 per cent of patients, respectively. An anterior open bite was registered in 17.7 per cent, crossbite in 8.2 per cent, and a reverse overjet in 3.2 per cent. A tooth width to arch length discrepancy was recorded in 12 per cent of teeth in the upper arch and in 14.3 per cent in the lower arch. The proportion of children estimated using the Dental Health Component of the IOTN to have a great or very great treatment need (grades 4 and 5) was 26.2 per cent. The higher values of treatment need during the mixed dentition period may account for temporary changes in the dentition and for the discrepancy in overjet and overbite. These discrepancies will be compensated in part during mandibular growth and development of the dental arch. Nevertheless, the findings indicate the early development of progressive malocclusion symptoms which are evidenced in the IOTN and concur with the acronym 'MOCDO' hierarchy (missing, overjet, crossbite, displacement, overbite). This early formation of progressive symptoms inhibiting or disturbing mandibular or maxillary growth or the development of the normal dental arch, i.e. crossbite, reverse overjet and increased overjet with myofunctional disorders, should be treated at an early stage.

Adolescent↗
PubMed2004

Torque capacity of metal and polycarbonate brackets with and without a metal slot.

The aim of the present study was to investigate slot deformation and the equivalent torque capacity of polycarbonate brackets with and without a metal slot in comparison with those of a metal bracket. For this purpose, the expansion characteristics and, in a further investigation, the labial crown torque of an upper central incisor, were measured in a simulated intra-oral clinical situation, using the orthodontic measuring and simulation system (OMSS). Three types of bracket with a 0.018 inch slot were tested: polycarbonate Brillant without a metal slot, Elegance with a metal slot and the metal bracket, Mini-Mono. For testing purposes the brackets were torqued with 0.016 x 0.022 inch (0.41 x 0.56 mm) and 0.018 x 0.022 inch (0.46 x 0.56 mm) ideal stainless steel archwires. In the activating experiments, significantly higher torque losses and lower torquing moments were registered with both rectangular archwires with the polycarbonate brackets than with the metal bracket. In the simulation tests, significantly higher torquing moments were registered with the metal bracket than with the polycarbonate brackets. The values for the Elegance bracket were between those of the Mini-Mono and Brillant brackets. The OMSS model approximates the clinical situation, with the torque loss being notably higher than in the in vitro activating experiments. This is due to the adjacent teeth giving the archwire additional play. In addition, the torquing process may twist the archwire, resulting in subsidiary forces. On the basis of the present results, all three brackets can be recommended for torquing. However, in view of the high torque losses, the torques programmed in the straightwire technique must be seen as questionable. Data should be provided by the manufacturer on the bending to be expected in polycarbonate brackets, which has to be offset by additional torque, or the bracket torque should be omitted from the technical specifications.

Dental Alloys↗
PubMed2003

Interocclusal clearance during speech and in mandibular rest position. A comparison between different measuring methods.

BACKGROUND AND AIM: The interocclusal clearance during speech and in mandibular rest position shows an interindividual variation and influences the stability of prosthodontic reconstruction or orthodontic therapy, especially in patients with deep bite or cover-bite. Exact determination of the vertical dimension, not always a simple matter in practice, is controversially discussed with respect to the methodology. The aim of the present investigation was to compare three methods for determining interocclusal clearance during speech and in mandibular rest position. PATIENTS AND METHODS: Extraoral manual registration and electronic registration were used to evaluate 33 malocclusion-free patients. The measurements were repeated to determine the reproducibility. For disturbance-free objectification, the freeway space, i.e. the interocclusal clearance in mandibular rest position, was also recorded cephalometrically. RESULTS: None of these registration methods displayed clear-cut superiority to the others. Electronic registration is very time-consuming and should be confined to special cases. Sources of error in manual registration are increased movement of the measuring points marked on the skin during mandibular movement and the free handling of dividers. CONCLUSIONS: This method can be used only in connection with mm. consonants. Speaking the word "Ohio" yielded excessively high values in all methods, so that this word has to be rejected as a speech sample. Cephalometric registration produced values with slight interindividual variations. In practice, however, this method is unsuitable for use with orthodontic patients because of the additional radiation exposure involved in producing an additional lateral cephalogram. For good reproducibility, practicing or frequent repeating of the measuring method prior to definitive measuring is essential.

Adult↗
PubMed2002

Torque capacity of metal and plastic brackets with reference to materials, application, technology and biomechanics.

AIM: The aim of the present study was to investigate slot deformation and the equivalent torque capacity of plastic brackets in comparison with those of a metal bracket in vitro and to simulate them under clinical conditions. MATERIAL AND METHOD: For this purpose the expansion characteristics of the brackets and their resistance to extraoral mechanical loading were compared in in-vitro activating experiments. In a further investigation, the labial crown torque of an upper central incisor was measured in a simulated intraoral clinical situation, using the Orthodontic Measuring and Simulation System (OMSS). Four types of bracket manufactured by Forstadent, Pforzheim, Germany, were tested: the plastic brackets Aesthetik-Line and Brillant, the latter from a previous series (Brillant-old) and from a modified series (Brillant-new), and the metal bracket MINI-MONO. For testing purposes the brackets were torqued with 0.016" x 0.022" (0.41 x 0.56 mm) and 0.018" x 0.022" (0.46 x 0.56 mm) ideal steel archwires (Remanium, Dentaurum, Ispringen, Germany). RESULTS: In the activating experiments, significantly higher torque losses and lower torquing moments were registered with both rectangular archwires with the plastic brackets than with the metal bracket. In the simulation tests, significantly higher torquing moments were registered with the metal bracket than with the plastic brackets. The OMSS model approximates the clinical situation, with the torque loss being notably higher than in the in-vitro activating experiments. This is due to the adjacent teeth giving the archwire additional play. In addition, the torquing process of the rectangular wire may deform the archwire, resulting in subsidiary forces. CONCLUSION: On the basis of the present results, the Brillant and Aesthetik-Line plastic brackets and the MINI-MONO metal bracket can be recommended for torquing. In view of the high torque losses, however, the torques programmed in the straight wire technique must be seen as questionable. It would be helpful to the practitioner if data were provided by the manufacturer on the flexing to be expected in plastic brackets, which has to be offset by additional torque or the possible renunciation of bracket torque.

Biomechanical Phenomena↗
PubMed2002

Orthodontic diagnostics and treatment planning in adults with temporomandibular disorders a case report.

BACKGROUND: Temporomandibular disorders are not an uncommon finding in adult patients undergoing orthodontic treatment. PATIENT AND METHODS: In a 25-year-old female patient with neutroclusion, bialveolar protrusion with anterior crowding, and mesial tipping of tooth 27 due to early loss of tooth 26, a unilateral clicking in the right temporomandibular joint was recorded as a secondary finding. Clinical and instrumental functional analysis revealed right-sided anterior disc displacement with reduction, which had been induced by forced guidance of the mandible to posterior. Space was to be gained by extracting tooth 41, by closing the residual gap at tooth 26, and by interproximal reduction of the dental enamel in the right upper buccal region. In addition, occlusal adjustment was to be undertaken subsequently to eliminate the forced guidance and to achieve a slightly overcorrected Class I relationship. RESULT: Treatment wit a complete fixed appliance fulfilled the treatment objectives, with normal functioning of the temporomandibular joint being achieved. This case of a patient with a temporomandibular disorder is used to illustrate steps in diagnosis and functional analysis. Steps which ensure not only a successful orthodontic outcome but also a beneficial orthopedic effect on the temporomandibular joint.

Adult↗
PubMed2002

4.2 Clinical records and global diagnostic codes.

A clinical record should include the personal demographic details of the patient, health status, diagnostic information and management/treatment options. However, clinical records are of little use without effective filing and retrieving systems. Coding is therefore necessary to deal with large amounts of differing data and a global coding system could be effectively developed through the use of information technology. The aim of this section was to review the main existing vocabularies and coding systems and to examine ways of improving their global application. It was concluded that global diagnostic codes would be beneficial to the patient, to the profession and to those responsible for strategic decisions concerning the delivery of health care. Extant dental clinical codes are not accepted widely or applied universally. There is an urgent need to identify existing coding systems and to assess their utility and potential for global application. Every effort should be made to include existing codes in the development of a global coding system on which all specialist areas would need to agree. This would require the provision of an overarching interdisciplinary focus and funding should be made available for this development and its implementation.

Cultural Diversity↗
PubMedDate not supplied

Orthodontic treatment in handicapped children: report of four cases.

Mentally and physically handicapped children show in the orofacial system motor-sensitivity disturbances and malocclusions of varying severity. These dysfunctions affect the breathing and speech ability and inhibit the food intake. Myotherapeutic exercises for strengthening of lip and tongue muscles and orthodontic treatment of the malocclusions help provide esthetic and functional improvements in these patients. The limited compliance necessitates a differentiated procedure during the diagnostic and therapeutic process and demands compromises in some cases.

Adolescent↗