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Biomedical subjects

J D Orthlieb

Publications and source records attributed to J D Orthlieb.

16 recordsLinked to original sources
PubMed2001

Comparison of occlusion in medieval and present-day populations in southeast France.

Two groups living in southeast France several centuries apart were compared to assess changes in occlusion from medieval times to the present day. The present-day sample included 82 people, and the medieval sample included the skulls of 58 people who lived between the 8th and the 17th centuries. Variations in tooth contacts were examined in accordance with Angle classification. A decrease in Class III occlusion (mesioclusion) was noted from medieval to present-day populations. The rate of Class II occlusion (distoclusion) has increased progressively and has became a general feature in the present-day population (34%). Although the rate of Class I occlusion has generally decreased from proto-historic and medieval times to the present day, it is still the highest percentage (45%) and thus the "normal" reference in European populations. This study highlights distoclusion in human teeth and allowed us to ask questions about functional, genetic, psychological, and environmental factors that cause this malocclusion as opposed to the global harmony that Angle described.

Adolescent↗
PubMed2000

Cephalometric estimation of vertical dimension of occlusion.

The literature does not establish a single proven method for determining lower facial height, which is called the Vertical Dimension of Occlusion (VDO), and the concept of a vertical comfort range is generally accepted. This study aimed to test the statistical significance of correlations of mandibular shape versus lower facial height in occlusion, using cephalometric measurements. Correlations for 505 consecutive healthy adults were calculated between angles that estimate the lower facial height and angles that estimate the mandibular shape. The mandibular angle (gonial) showed a higher coefficient of correlation (r = 0.691) than the inferior gonial angle. The dispersion remained large, i.e. r2 = 0.478. Cephalometric measurements, despite theirs imperfections, could help the practitioner to understand what the best course of treatment would be in order to obtain a lower facial height in occlusion showing a skeletal harmony with the mandibular shape.

Adult↗
PubMed2000

[Influence of saggital inclination of the teeth and the orientation of the occlusal plane on mesial drift in the dental arch].

As a rule, the occlusal plane in man is not flat but curved in the three dimensions. This curved organization is related to a specific phenomena: the continuity of the dental arch without diastema. The Page's proposal of the tangent law explains the sagittal organization of the mandibular teeth by geometrical analyses. A cephalometric analysis of 485 subjects, in natural dentition, is the basis for the present statistical study of the mandibular teeth sagittal inclination, related to the direction of the tangent. Mandibular incisors follow the tangent law, but the long axis of the posterior mandibular teeth exhibits a postero-anterior and progressive differential angle with the direction of the tangent: 15 degrees, 20 degrees, 25 degrees, 28 degrees. The differential angle with the direction of vertical strength during closure movement generates an horizontal strength component, with a tendency to create a forward tooth movement. This horizontal component of force is tightening the proximal contacts, maintaining the continuity of the dental arch: it also originates the mesial "drift" and mandibular incisor crowding.

Adult↗
PubMed1999

[RMI of dysfunctional temporomandibular joint (TMJ). Value of gradient-echo T1 sequences in the evaluation of bony structures].

PURPOSE: To identify and classify the different types of bony changes of the condyles in patients with disorders of the temporomandibular joint (TMJ). MATERIALS AND METHODS: Since 1993, we have imaged over 600 patients with 0.5T MR unit by using gradient-echo T1-weighted sequences in the sagittal and coronal planes. RESULTS: We will first describe the appearance of the normal TMJ. Then, we will introduce the concept of "Condylo-diskal disunion" using a three grade classification system. We will then describe three patterns of condylar changes: adaptive remodeling, either anterior or more frequently posterior, degenerative lesions with subchondral sclerosis, erosive lesions due to synovial hyperplasia. CONCLUSION: Using a 0.5T MR unit, a GRE T1 sequence is useful to identify lesions of the disk and detect bony changes. In addition, the tissues posterior to the disk can also be assessed on postcontrast images.

Diagnosis, Differential↗
PubMed1998

[The contribution of standard radiographs in the evaluation of masticatory system dysfunction].

Conventional x-ray films (orthopantomogram, teleradiogram) visualize many signs of dysfunction of the manducatory apparatus (DAM). Progress in our knowledge of the pathophysiology of DAM has brought new light to these radiographic signs. The orthopantomogram allows an assessment of modifications in muscle insertion zones secondary to their dysfunction and, more difficulty, the articular remodeling of the TMJ, mainly of the mandibular condyle and the articular space. The lateral teleradiogram studied by architectural and structural analysis provides information on the biomechanical balance of the cranio-facial structures and, especially, on the position of the mandibular rami. These standard radiograms are indispensable in the differential diagnosis, useful in the etiological diagnosis and are preliminary examinations prior to using other imaging techniques (MRI, CT). Standard films are easily reproducible for post-therapy follow-up.

Biomechanical Phenomena↗
PubMed1997

The curve of Spee: understanding the sagittal organization of mandibular teeth.

The tangent law explained the sagittal organization of the mandibular teeth by geometrical analyses. According to this concept, the long axis of all mandibular teeth must converge at one point in the circle of the "curve of Spee", and this point is diametrically opposed to the condylar point. A cephalometric analysis of 470 patients was the basis for this statistical study of the radius of the curve of Spee. The mean radius was approximately 80 mm. The mandibular incisors followed the tangent law, but the long axis of the posterior mandibular teeth exhibited a progressive differential angle (postero-anterior) with the direction of the tangent (15 degrees, 20 degrees, 25 degrees, 28 degrees). This differential angle generates a horizontal strength component with tendency to forward tooth movement, tightening of the proximal contacts. The use of this cephalometric reference could help the dentist to determine a more suitable organization of the occlusion in the sagittal plane.

Adult↗
PubMed1992

[Otologic manifestations of the pain dysfunction syndrome of the stomatognathic system].

Phylogenesis, ontogenesis and anatomy explain the close relationship between temporo-mandibular joint and the middle ear and can therefore help understanding otologic symptoms such as: otalgia which often correspond to articular and muscular pain irradiation (coming from sterno-cleido-mastoid, lateral and medial pterygoid, deep layer of the masseter and temporal muscles); acouphens and ear block sensation that could be caused by a spasm extension of the manducatory (i.e. medial pterygoid) to levator and tympani tensors. These three muscles, which originate from the first branchial arch, have a proprioceptive sensitivity and share the same innervation. What is more tensor and levator veli exchange certain muscular fibers. Tensor tympani spasm can be held responsible both for a decrease or abolition of the Klockhoff's reflex, together with a decrease of the stapedian reflex, the latter due to tympani rigidity induced by a spasm of the tensor tympani.

Ear Diseases↗
PubMed1992

[The discal system of the temporo-mandibular junction].

The discal apparatus represent the intra-articular part of the lateral pterygoid muscle tendon, which is differentiated in front of articular surfaces. It is involved in craniomandibular shock absorbing, joint proprioception, and also plays an important part in both condylar growth and morphogenesis. This is to emphasize the different roles of this apparatus, which should be religiously preserved, its lesions being, most of the time, irreversible and cause of TMJ disorders.

Humans↗
PubMed1990

[Statistical analysis of functional interrelations between anterior guidance and posterior determinants].

During the last decade, the concept of an effective, even steep anterior guidance did evolve toward the description of a "kinder" or "softer" anterior guidance which, while ensuring the disclusion of the posterior teeth, leaves some anterior functional freedom. It then becomes necessary to determine more precisely the criteria for diagnosis, orthodontic treatment, prosthetic restoration of anterior functional surfaces. In order to reveal some functional agreement between an anterior and posterior guidance, the analysis of the functional morphology of antero-maxillar teeth in relation to their skeletal context was proposed, in a study of 33 cases, so as to correlate the condylar steepness measured by axiography. It should be noted that a decreasing gradient exists between the mean respective values of the functional slopes of the central incisors (S1 = 64.3 degrees), and lateral incisors (SF1 = 53.5 degrees) and the canine (Cf = 51.8 degrees). Although the cingular surface S1 does not appear to have any influence on the posterior guiding factor (r = 0.1), in fact the anterior functional surface which is stategic in mastication, is located on the occlusal surface of the palatol side (S2) of the antero-maxillary teeth. The correlation is significant (r = 0.325) when the anterior guidance (incisives and canines) is associated to the mean condylar value more than being correlated to the mean functional value of the central incisor alone. It thus appears logical that the functional modeling of the articular cavities be influenced by the overall anterior guidance and not by the single central incisor. It has also been possible to emphasise the influence of the orientation of the occlusal plane in the anterior functional relationship (r = 0.547); thus, the anterior guidance appears to have to be assessed over a "relative overall analysis": overall: meaning the overall anterior guidance, i.e. the six anterior maxillary teeth; relative: meaning measured in relation to the occlusal plane. This concept of relative overall analysis of the anterior guidance, developed using a simple computerised program, will allow the diagnosis and anterior prosthetic or orthodontic restoration to be facilitated.

Adult↗