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Biomedical subjects

G Boering

Publications and source records attributed to G Boering.

At least 91 records · Page 5Linked to original sources
PubMed1990

Temporomandibular joint osteoarthrosis and internal derangement. Part I: Clinical course and initial treatment.

A certain natural sequence exists in the occurrence of the major clinical symptoms of 'craniomandibular dysfunction', usually leading to a final stage in which the disease is burned out. Most clinical symptoms can be explained by an internal derangement. As long as we do not know the real cause of, and the exact relationship between, osteoarthrosis and internal derangement, management should be primarily directed at the symptoms. In this paper, the major stages of the disorder are described and illustrated with three characteristic cases.

Adolescent↗
PubMed1990

Temporomandibular joint osteoarthrosis and internal derangement. Part II: Additional treatment options.

In some cases of temporomandibular joint osteoarthrosis and internal derangement, the initial treatment needs to be supported by additional treatment modalities. In this paper, the basic principles of the most common additional modalities used are discussed. Orthopaedic appliances are used to either stabilize, or reposition the mandible. Consequently, there are two splint types: the stabilization splint and the repositioning splint. The major indication for applying the former is to decrease the load imposed on the joint. Secondary effects are stabilization of the occlusion and masticatory muscle relaxation. The repositioning splint may be used in some cases to reduce a displaced articular disc. Physical therapy is often used to mobilize the joint and to re-educate mandibular movement patterns. Based on the stages of temporomandibular joint osteoarthrosis and internal derangement, guidelines are given for the treatment strategy to be followed in the management of this common disorder.

Cartilage, Articular↗
PubMed1989

Experimental fractures of the mandibular body of sheep and dogs. A new technique.

In order to create artificial fractures in animals resembling those which occur naturally, a new technique for fracture production was developed. Using a specially designed clamp, artificial fractures were produced in the mandibular body of seven sheep and 12 dogs. Radiographical analysis of the effects of the clamp on the mandibular body showed simple, single vertical fractures in the buccal cortex, inferior border and the alveolar process comparable to those which occur naturally. Using the technique described it was possible, in all cases, to carry out treatment with the use of 4-hole poly(L-lactide) plates and screws.

Animals↗
PubMed1989

Osteoarthrosis as the cause of craniomandibular pain and dysfunction: a unifying concept.

It has been demonstrated that osteoarthrotic changes in the temporomandibular joint (TMJ) and in other synovial joints show a similar course, both clinically and (ultra)microscopically. Initially, cartilage changes and possibly also changes in the synovial membrane set up a vicious cycle of cartilage breakdown accompanied by attempts at repair. When the degradative process exceeds the response of repair, the osteoarthrotic disorder progresses into clinically detectable stages. Frequently, the gliding capacity of the articular disc is also impaired, giving rise to an internal derangement. In this article, a concept is presented in which it is suggested that in many cases of craniomandibular pain and dysfunction TMJ osteoarthrosis is the basic disorder.

Bite Force↗
PubMed1989

Bone-plates and screws of bioabsorbable poly (L-lactide)--an animal pilot study.

Poly (L-lactide), a polymer of lactic acid (PLLA), with an extremely high molecular weight (Mv up to 1 x 10(6] has been synthesised under strictly controlled conditions resulting in a new microporous material with excellent mechanical properties. Bone-plates and screws machined from PLLA were used for fixation of two artificial mandibular fractures in sheep effected by a specially designed bone clamp. Fracture healing was uneventful without visible callus formation. Plates and screws of PLLA gave good stability over a sufficiently long period to enable normal fracture healing. Application in humans seems to be justified.

Absorption↗
PubMed1989

Comparisons in the treatment of facial trauma.

In 1980 a survey was conducted of the methods employed by OMF surgeons in the United Kingdom on the treatment of facial injuries. In 1986 a similar questionnaire was circulated in the UK with the addition of questions about clinical management. Towards the end of 1986 at a meeting in Amsterdam, arrangements were made for similar questionnaires to be circulated in The Netherlands, the USA and later in India and Hong Kong. The results recorded were as follows: UK: 164; The Netherlands: 94; USA: 1999; India: 20; Hong Kong: 5. This survey has revealed differences in the treatment of maxillofacial injuries in the countries concerned. There were differences in the means of fixation of fractured mandibles and in the types of anaesthesia used. The Americans were more likely to use extra oral surgical approaches for their lower border wirings or platings and were liable to operate on fractured mandibular condyles. The acceptability of patients being sent from the operating room with jaws wired together is confirmed by the fact that 95% of British and American OMF surgeons do this. The British OMF surgeons are much more likely to use fixation other than IMF in middle third injuries and are likely to use extra oral cranial fixation. Both the Dutch and the Americans are not so concerned about maxillary mobility and when they do employ fixation almost always use internal skeletal fixation. The approach to the reduction of a fractured malar is markedly different. The British are mainly using the Gillies approach, whereas the Dutch use the facial hook and the Americans a lower lid or brow approach.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Bio-absorbable plates and screws for internal fixation of mandibular fractures. A study in six dogs.

Bio-absorbable plates and screws were used for internal fixation of artificially created mandibular fractures in 6 dogs. The plates and screws were fabricated from a block of poly(L-lactide) (PLLA), with a high molecular weight. The material is microporous and has excellent mechanical properties. Plates and screws were inserted in accordance with Champy's principles on internal fixation. Clinical and radiographical follow-up and examination of the fracture site under general anesthesia showed that all fractures healed without callus and without complications. The plates or screws did not fail, despite the tensile strength of the PLLA used is less than stainless steel or any other metal. An explanation for their successful application may be the high impact resilience of this material. The proprioceptive mechanisms, however, that keep the dogs from maximal loading of their broken mandibles, may also play a role. Plates and screws of this bio-absorbable PLLA appear to be an attractive alternative for internal fixation of mandibular fractures and certainly for less loaded fractures of the human skeleton. The necessity to remove metallic osteosynthesis can be avoided.

Absorption↗
PubMed1989

A proposed classification of temporomandibular disorders based on synovial joint pathology.

Classifying temporomandibular disorders is essential for descriptive and diagnostic reasons. The etiology of many temporomandibular joint (TMJ) disorders is unknown and lack of scientific agreement about etiologic concepts contributes to controversies about the real nature of TMJ disorders. Although many classifications have been suggested, mostly based on etiologic assumptions, a generally accepted classification is not yet available. Considering the TMJ as a true synovial joint, comparable to all other joints in the body, implies that the classification of disorders of the masticatory system should be consistent with the approach to musculoskeletal disorders in other parts of the body. Based on this criterium and on the considerable amount of information available in the literature, a classification of TMJ disorders is here proposed for general use.

Bursa, Synovial↗
PubMed1989

Secondary retention of permanent molars: a histologic study.

The etiology of secondary retention is not well understood, but ankylosis is often considered to be an important factor in primary molars. Data concerning the mechanism of secondary retention in the permanent dentition are insufficient, although a possible role of ankylosis has been suggested. In order to analyze the frequency of occurrence and localization of ankylosis in secondarily retained permanent teeth, 26 secondarily retained molars and for comparison six normal molars were studied histologically. These data were compared with the clinical and radiographic findings. Areas of ankylosis were observed along the roots of all secondarily retained molars. In 81% of the cases these areas were located at the bifurcation and interradicular root surface. No signs of ankylosis were found in normal molars. When these results were compared with the clinical and radiographic data, it was obvious that the latter gave many false negative results, because the areas of ankylosis were often too small to be detected clinically or radiographically.

Adolescent↗
PubMed1989

[Disorders of the temporomandibular joint. 1. Concept and classification].

The nature and causes of pain and disturbances of the temporomandibular locomotor system are subjects of controversy. The strategy of management of temporomandibular disorders considerably depends on the basic approach to the problem. Analysing craniomandibular pain and dysfunction in terms of general pathology of synovial joints has major consequences for the terminology and classification of these disorders. In this article, general synovial joint pathology forms the basis of the classification of the most common disorders of the mandibular locomotor apparatus. Based on this classification, a frame for the management of temporomandibular disorders is presented.

Humans↗
PubMed1989

[Disorders of the temporomandibular joint. 2. Diagnosis and strategies for management].

Management of temporomandibular disorders should be based on a thorough clinical and radiographic examination, leading to a specific diagnosis. Contributing factors should be detected and the aim of the treatment should be clear. The initial treatment is focussed on the management of acute symptoms, explication of the nature of the disorder and of the impact of contributing factors. Depending on the stage of osteoarthrosis and internal derangement, several treatment modalities may be considered. This article provides practical guidelines for determining the strategy for management of temporomandibular joint osteoarthrosis and internal derangement.

Humans↗
PubMed1988

Synovial chondromatosis of the temporomandibular joint: a light and electron microscopic study.

The light and electron microscopic features of synovial chondromatosis of the temporomandibular joint of one patient are presented. The affected synovial membrane and the cartilaginous nodules, which were freely movable in the joint space as well as attached to or incorporated in the synovial membrane, were examined. Light microscopic observation revealed metaplastic formation of these nodules within the subintima of the synovial membrane. Different stages of development of the nodules were observable. Electron microscopic examination of the cartilaginous nodules revealed features of mature chondrocytes well endowed with rough-surfaced endoplasmic reticulum and Golgi apparatus. The synovial intimal cells had a differentiated ultrastructural appearance. Several cytoplasmic organelles of the chondrocytes and intimal cells are described. The results of this study support the benign nature of synovial chondromatosis.

Cartilage↗
PubMed1987

Resorbable materials of poly(L-lactide). VI. Plates and screws for internal fracture fixation.

Poly(L-lactide) (PLLA) with an extremely high molecular weight (Mv up to 1 X 10(6)) was synthesized at a low catalyst concentration (0.015 wt%) and temperatures between 100-110 degrees C. Besides good mechanical properties the as-polymerized PLLA exhibited a microporous structure. Plates and screws of this material were used for the treatment of mandibular fractures, both in dogs and in sheep. Bone healing was uneventful and proceeded without callus formation or signs of inflammation. Fracture healing was accompanied by a progressive degradation of the microporous implants of PLLA.

Animals↗
PubMed1987

Resorbable materials of poly(L-lactide). VII. In vivo and in vitro degradation.

In vivo and in vitro degradation of high molecular weight poly(L-lactide) used for internal bone fixation has been investigated. Within 3 months as-polymerized, microporous PLLA (Mv = 6.8-9.5 X 10(5] exhibited a massive strength-loss (sigma b = 68-75 MPa to sigma b = 4 MPa) and decrease of Mv (90-95%). At week 39, the first signs of resorption were evident (mass-loss 5 wt%). Except for dynamically loaded bone plates no differences between in vivo and in vitro degradation of PLLA were observed. The increase of crystallinity of PLLA upon degradation (up to 83%) is likely to be attributed to recrystallization of tie-chain segments. A more ductile PLLA exhibiting a lower rate of degradation was prepared by extraction of low molecular weight compounds with ethyl acetate.

Animals↗