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Biomedical subjects

B R Merz

Publications and source records attributed to B R Merz.

12 recordsLinked to original sources
PubMed2001

Segmental distraction osteogenesis of the anterior alveolar process.

PURPOSE: This article describes a nonextraction therapy for patients with anterior tooth crowding in the mandible or with an unfavorable relation between the anterior dentoalveolar area and the skeletal base. The method involves the gradual repositioning of the dentate segment by use of distraction osteogenesis. PATIENTS AND METHODS: The method was applied in 25 patients. Indications comprised skeletal Class II patients with crowding, Class I patients with crowding, and Class III patients requiring decompensation before orthognathic surgery. A special hinge-joint bone plate was developed to allow the rotation of the anterior bone segment into the desired position. The gradual repositioning was achieved with orthodontic appliances. RESULTS: The procedure was successful in all patients. The typical advancement at the incisal edge was 2 to 5 mm. CONCLUSION: This method represents a new approach for nonextraction therapy in the mandible. It requires no soft or hard tissue grafting and results in favorable tissue conditions at the distraction site.

Alveolar Process↗
PubMed2000

Predetermined implant positioning by means of a novel guide template technique.

This paper presents a novel guide template technique for implant placement. In esthetic implant dentistry with its restoration-driven implant placement as well as in complete-arch cases with multiple implants, the precise positioning and angulation of dental implants is crucial for achieving the desired prosthetic results. Difficulties in implant positioning may arise especially with grafted jaws resulting from communication problems between surgeon and prosthodontist. This method may alleviate some of the problems common to conventional template techniques, where the drill is usually directly guided by the template. The key idea is to fixate the implant position and angulation by the help of Kirschner wires which are inserted in the alveolar ridge right through the mucosa before elevation of a mucoperiosteal flap. Thanks to this sequence, the template for guiding the wires may be positioned precisely, even on grafted edentulous ridges. After the insertion of the wires, the bone is exposed and the implant cavities prepared with a trephine drill guided over the wires alone or over wires combined with a special guidance cylinder fitting the trephine drill. The method may be combined with different planning and radiological techniques. Since the use of the template is detached from the actual drilling process, the danger of introducing debris of plastic or metal into the preparation site may be avoided. The present technique might be helpful for difficult cases by improving communication between prosthodontist and surgeon and also render additional security to the surgeon with less routine in dental implant insertion.

Dental Implantation, Endosseous↗
PubMed2000

The development of the ITI DENTAL IMPLANT SYSTEM. Part 2: 1998-2000: Steps into the next millennium.

In 1998 and 1999, the ITI DENTAL IMPLANT SYSTEM underwent its greatest modification since it came into existence. Prosthetic possibilities with regard to implant position transfer and master-cast manufacturing have been considerably enlarged by synOcta, surgical instruments have been improved in a multitude of ways and, by introducing SLA, the sand-blasted, large grit, acid-etched surface for oral implants which shortens time to loading by 50%, the ITI and Straumann have achieved a major breakthrough in surface technology.

Dental Abutments↗
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

Mechanobiological adaptation of subchondral bone as a function of joint incongruity and loading.

Computed tomography (CT) has been employed to determine non-invasively the distribution of subchondral bone density in joints and to evaluate their dominant loading pattern. The objective of this study was to investigate the relationship between subchondral bone adaptation, joint incongruity and loading, in order to determine to what extent the loading conditions and/or geometric configuration can be inferred from the distribution of subchondral density. Finite element models of joints with various degrees of incongruity were designed and a current remodeling theory implemented using the node-based approach. Appropriate combinations of joint incongruity and loading yielded subchondral bone density patterns consistent with experimental findings, specifically a bicentric distribution in the humero-ulnar joint and a monocentric distribution in the humero-radial joint. However, other combinations of incongruity and loading produced similar subchondral density patterns. Both the geometric joint configuration and the loading conditions influence the distribution of subchondral density in such a way that one of these factors must be known a priori to estimate the other. Since subchondral density can be assessed by CT and joint geometry by magnetic resonance imaging, the dominant loading pattern of joints may be potentially derived in the living using these non-invasive imaging methods.

Adaptation, Physiological↗
PubMed1997

Implant dentistry--development and current focus.

Today, implant dentistry plays an important role in the maintenance of chewing function and oral health. For thirty years now oral implants and methods for implantation have been developed further to assure a lifetime stability of these devices and to optimize function and esthetics. Starting with the treatment of fully edentulous patients, oral implants are now used for the reconstruction of partially edentulous patients as well. Thereby, implants not only replace missing teeth but also help to preserve intact remaining teeth. They are usually incorporated to improve the patient's subjective chewing comfort. The present paper gives an overview of the development and the current state of the art of oral implants, as well as their clinical indications.

Animals↗
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

The development of the ITI Dental Implant System as a model for the cooperation between research and industry.

For thirty years now oral implants and methods for implantation have been developed further to assure a lifetime stability of these devices and to optimize function and esthetics. Coming from osteosynthesis the Institut Straumann in cooperation with leading clinicians had a considerable share in this development. Out of this longtime cooperation an institutionalized form was devised, where clinicians, material scientists and engineers were united in the International Team for oral Implantology (ITI). This scientific organization, although legally and financially independent from Institut Straumann, works in close cooperation with the company in an unique form of symbiosis. The ITI takes care of research and education of clinicians and practitioners and it gives the needed input for the development of new products to the Institut Straumann as its exclusive licensee. The company again pays license fees to the ITI Foundation enabling thus a continuous scientific clinical research. Over many years a whole philosophy and implant system - the ITI Dental Implant System - was developed this way with its sound scientific background.

Cooperative Behavior↗
PubMedDate not supplied

Mechanics of the implant-abutment connection: an 8-degree taper compared to a butt joint connection.

This paper presents aa comparison between the 8-degree Morse Taper and the butt joint aa connections between an implant and an abutment. Three-dimensional, non-linear finite element models were created to compare the 2 connection principles under equal conditions. The loading configuration was thereby modeled according to a test setup actually used for the dynamic long-term testing of dental implants as required for regulatory purposes. The results give insight into the mechanics involved in each type of connection and are compared to actual findings with the testing machine. The comparison indicates the superior mechanics of conical abutment connections and helps to explain their significantly better long-term stability in the clinical application.

Dental Abutments↗