Biomedical subjects

A Obrez

Publications and source records attributed to A Obrez.

6 recordsLinked to original sources

PubMed1998

The effect of musculoskeletal facial pain on registration of maxillomandibular relationships and treatment planning: a synthesis of the literature.

STATEMENT OF PROBLEM: A significant number of patients exist who are in need of prosthodontic rehabilitation and who at the same time report musculoskeletal pain in the facial area. PURPOSE: This article, which is based on an assessment of both the past and the most recent basic science and clinical literature, evaluates the effect of musculoskeletal facial pain on two static (physiologic rest position and centric relation) and two dynamic (protrusive border and lateral border movements) maxillomandibular relationships. MATERIAL AND METHODS: To find the relevant studies addressing the association between musculoskeletal facial pain and maxillomandibular relationships, a MEDLINE search was conducted, which was complemented by a hand search in selected journals. RESULTS AND CONCLUSIONS: Musculoskeletal facial pain seems to variably affect the aforementioned positions and movements. Hence, the validity of maxillomandibular registrations in patients with existing facial pain is questioned. In those patients with facial pain who simultaneously are in need of a prosthodontic rehabilitation, clinicians should be cautious with regard to the timing of the restorative procedures.

Centric Relation↗

PubMed1998

New acrylic resin composite with improved thermal diffusivity.

STATEMENT OF PROBLEM: Studies have shown that physical characteristics of denture base materials may affect patient acceptance of denture prostheses by altering sensory experience of food during mastication. Thermal diffusivity is one material property that has been cited as being important in determining gustatory response, with denture base acrylic resins having low thermal diffusivity compared with denture base metal alloys. PURPOSE: This study prepared and characterized experimental acrylic resin composite material with increased thermal diffusivity. MATERIAL AND METHODS: Sapphire (Al2O3) whiskers were added to conventional denture base acrylic resin during processing to achieve loadings of 9.35% and 15% by volume. Cylindrical test specimens containing an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 degree to 70 degrees C). RESULTS: Thermal diffusivities of the sapphire containing composites were found to be significantly higher than the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the volume percentage of sapphire filler, which suggested that the high aspect ratio ceramic particles formed a pathway for heat conduction through the insulating polymer matrix. CONCLUSION: The thermal diffusivity of denture base acrylic resin was increased by the addition of thermally conducting sapphire whiskers.

Acrylic Resins↗

PubMed1996

Jaw muscle pain and its effect on gothic arch tracings.

Perceived changes in occlusion and decreased range of motion are often expressed by patients with masticatory muscle pain. The adverse loading of craniomandibular tissues that results from an inadequate maxillomandibular relationship in combination with the coexisting dysfunction is widely regarded as the cause of pain. This study was designed to test whether pain can cause significant changes in position of the mandible and therefore form the basis for any perceived changes in the maxillomandibular relationship. A second objective was to determine whether pain can cause changes in the mandibular range of motion. Five subjects who rated pain intensity on a visual analog scale were used in a single-blind, randomized, repeated-measures study design. Tonic muscle pain was induced by infusion of 5% hypertonic saline solution into the central portion of the superficial masseter muscle. Isotonic saline solution was used as a control, with subjects blinded to the type of substance given. The effect of pain on the position of the apex of the gothic arch tracing, the direction of the lateral mandibular border movements, and the mandibular range of motion was studied in a horizontal plane with minimal occlusal separation. Pain significantly affected the position of the apex of the gothic arch tracing in anterior (F = 11.46, p = 0.03) and transverse (F = 35.0, p = 0.004) directions. Similarly, pain affected the orientation of the mandibular lateral border movements (F = 12.44, p = 0.02) and their magnitude (F = 14.97, p = 0.01). All pain-induced effects proved to be reversible. The observed effect of pain can explain the perceived change of bite that is frequently noted by patients with orofacial pain. This study provided evidence of an alternative causal relationship between pain and changes in occlusal relationship and questions occlusal therapy as treatment, directed toward the elimination of the underlying cause in patients with masticatory muscle pain.

Adult↗

PubMed1996

Mandibular molar teeth and the development of mastication in the miniature pig (Sus scrofa).

The only components of the orofacial complex that are fully developed as soon as they establish function are the occlusal surfaces of teeth. It is usually assumed that the occlusal surface of the molar teeth influences the orientation of the power stroke in spite of the fact that the data supporting this claim are lacking. The purpose of this longitudinal study was therefore to determine whether or not this hypothetical form-function relationship existed during development and whether or not it was related to growth. Serial dorsoventral and lateral radiography, and dorsoventral cineradiography were performed during natural feeding of 5 Hanford miniature pigs (Sus scrofa) of both genders between their 8th and 18th weeks. Sequences of power strokes were analyzed frame by frame and compared between sessions, and related to the position of the fourth primary mandibular molar (dm4). The changes in direction of the power stroke and in position of the dm4 relative to the midline were subsequently related to growth. The results of this study indicate that changes in orientation of the power stroke, though significant only on the balancing side, occur independently of the repositioning working and balancing side mandibular molars, as well as of skeletal growth. The null hypothesis that the mandibular primary molars influence the transverse orientation of the power stroke during growth is therefore refuted.

Animals↗

PubMed1993

Bone growth and periosteal migration control masseter muscle orientation in pigs (Sus scrofa).

During growth the muscles of mastication alter their lines of action. Research on long bones indicates that the apparent migration of muscle attachments is due to the movement of the periosteum relative to the underlying bone. To assess whether the pig masseter muscle follows the periosteum during growth, implants of titanium granules in a gelatin matrix were placed simultaneously in various parts of the masseter muscle and its periosteal and bony attachments. Growth movements of these tissues were followed radiographically for 2 months. Granule position was verified histologically. Periosteal movement was the dominant growth process at the insertion of the masseter. All implants migrated caudally relative to the mandible. However, a strong position effect was seen dorsoventrally: implants placed high in the ascending ramus migrated dorsally as well as caudally; low implants migrated only caudally. This differential migration, ascribed to the influence of the condyle, accounts for the increasing horizontal orientation of dorsal fibers. A similar differential was seen along the rostrocaudal axis of the ramus. In contrast to the insertion, the origin of the masseter from the zygomatic arch shows no periosteal movement. Rather, the entire bone-muscle complex becomes displaced by sutural growth, leading to increasing vertical orientation of the masseter. Thus two different aspects of skull growth are responsible for the change in muscle anatomy.

Animals↗

PubMedDate not supplied

Opinions and feelings on eating with complete dentures: a qualitative inquiry.

Our knowledge of variables affecting the coping strategies that lead to acceptance of foods in populations wearing complete dentures is limited. Focus groups were conducted with the specific aim of determining factors responsible for successful adaptation to chewing with complete dentures. Each of the five focus groups consisted of eight to 15 participants (mean = 11; mean age = 64 yrs), of mixed gender, with at least five years of denture-wearing experience (mean = 7 years), and with groups varying in their socio-economic and ethnic backgrounds. Participants' statements (n = 324) were sorted for their content, by consensus between the two investigators, into 12 conceptually independent domains (listed in decreasing order of frequency of mention): foods and food textures causing difficulties when eating, foods being avoided, stability and retention of dentures, social constraints, bolus size, general satisfaction with the current dentures, general experience with dentures, sensation of temperature, experience of pain during chewing, experiences with taste, experiences with rinsing the dentures after eating, and time involved with chewing. In addition, further analysis of statements showed that food texture was the most commonly mentioned with foods that were either difficult to chew or avoided. These perceptions significantly affected the choice of food. The results of this qualitative study indicate that food texture is one of the major factors influencing the choice of a coping strategy by denture wearers when trying to overcome difficulties in chewing specific foods. As such, food texture may have a significant effect on patients' success in the process of their functional adaptation.

Adaptation, Psychological↗