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Biomedical subjects

K Zarrinnia

Publications and source records attributed to K Zarrinnia.

14 recordsLinked to original sources
PubMed1996

The viscoelastic properties of the human temporomandibular joint disc.

PURPOSE: This study evaluated the viscoelasticity of the human temporomandibular joint (TMJ) disc by comparing the moduli of elasticity generated by compressing disc specimens under two different loading rates. MATERIALS AND METHODS: Twelve TMJ disc specimens 4.25 mm +/- 0.15 mm in diameter were obtained from fresh cadavers between 65 and 75 years of age. One group of specimens was subjected to a loading rate of 0.00127 mm/sec, and the other was subjected to a loading rate of 0.000635 mm/sec. Modulus of elasticity was calculated from the stress and strain values obtained from each specimen. RESULTS: When the specimens were subjected to an average 0.00127 mm/sec loading rate, a mean modulus of elasticity of 0.541 N/mm2 was derived. When an average 0.000635 mm/sec loading rate was used, a mean modulus of elasticity value of 0.211 N/mm2 was derived. These two mean values were significantly different, as indicated by the results of a one-tailed t-test. CONCLUSIONS: Analysis of the data showed that the human TMJ disc specimens became stiffer as the loading rate increased.

Aged↗
PubMed1996

The effect of acetaminophen, ibuprofen, and misoprostol on prostaglandin E2 synthesis and the degree and rate of orthodontic tooth movement.

The present study compared the effect of acetaminophen, ibuprofen and misoprostol on PGE2 synthesis and orthodontic tooth movement. Guinea pigs were randomly assigned into one of three test groups or a control group. Each group received study treatments every 12 hours as an orthodontic force was applied to the maxillary incisors. Direct linear measurements of tooth separation were recorded at days 2, 4, 6, 10, and 11, and inflammatory exudate from the periodontal ligament (PDL) space was extracted and quantitatively analyzed radioimmunologically for the presence of PGE2 at days 4 and 9. Comparing the concentration of PGE2 in sample extracts, a significant difference (P = 0.001) was found among drug groups. A highly significant difference was found between the mean tooth separation among the various drug groups (P < 0.001). At day 11 the misoprostol group exhibited 4.49 +/- 0.49 mm of separation; ibuprofen 2.56 +/- 0.11 mm, and the control and acetaminophen groups exhibited similar degrees of tooth separation: 3.31 +/- 0.07 mm and 3.31 +/- 0.08 mm, respectively. A highly significant difference occurred between the mean rates of tooth separation among the various drug groups after day 8 (P < 0.001). Results of this study suggest that acetaminophen is the analgesic of choice for the relief of minor discomfort associated with orthodontic treatment.

Acetaminophen↗
PubMed1995

The effect of different debonding techniques on the enamel surface: an in vitro qualitative study.

The purpose of this in vitro study was to evaluate the enamel surface structure subjected to various techniques of debonding orthodontic attachments and to develop a technique for residual adhesive removal that restores the enamel surface as closely as possible to its pretreatment condition without introducing iatrogenic damage. Enamel surface structure was examined with a scanning electron microscope before bonding of twin metal brackets to 60 previously extracted premolars with two heavily filled composite resins. Two groups, each consisting of 30 teeth, were equally subdivided into 10 subgroups. The first three subgroups were used to compare the efficacy of three bracket removing instruments. Since there were no differences in the debonding properties between the two resins, the two groups were combined. In this way, each subgroup (n = 6) could be used for a more meaningful comparison. On the basis of the results of this comparison, the bracket removing instrument that produced the most consistent separation at the bracket-adhesive interface was used in the remainder of the study. After appliance removal, the teeth were again examined microscopically and photographed, and seven different procedures for residual resin removal were compared. After resin removal, the final polished enamel surface was followed by microscopic evaluation. Results of this study show the bracket removing plier produced the most consistent separation at the bracket-adhesive interface, leaving the enamel surface intact. Carbide burs at high speed and air coolant proved to be efficient in residual resin removal, but when used alone, failed to produce a satisfactory enamel surface. After the removal of residual resin, graded medium, fine, and superfine Sof-Lex finishing disks (Unitek Corp., Monrovia, Calif.) produced surfaces that could be readily restored satisfactorily after receiving a final polish with a rubber cup and Zircate paste.

Adhesives↗
PubMed1993

Bimaxillary protrusion in black Americans--an esthetic evaluation and the treatment considerations.

This study attempted to discover what black Americans find attractive about their profile. Fifteen black patients (eight males, seven females) were selected at random and used as models. Lateral photographs were taken on each patient, and a computer was used to alter the profiles to depict different levels of bimaxillary protrusion. Each patient was manipulated into four different profile types according to specific numerical guidelines. A vertical reference line from soft tissue glabella, perpendicular to Frankfort horizontal, was used to measure the lip position. In each profile type only the horizontal lip position was altered. The four profile types were classified as S (straight) BM1, (bimax one), BM2 (bimax two) and BM3 (bimax three). The S profile was considered a straight or white facial profile, and the BM3 was an extreme example of bimaxillary protrusion. The photographs were surveyed among black and white laypersons, general dentists, and orthodontists. The results found the BM1 profile to be the most attractive. This was consistent with all groups surveyed. The BM1 profile would be considered a slightly convex profile and is more protrusive than white orthodontic norms. In this study comparisons of this profile to other standards are made and treatment considerations for black patients are discussed.

Adult↗
PubMed1990

Frontal cephalometric study of dentofacial morphology in children with bilateral clefts of lip, alveolus and palate.

The transverse dentofacial morphology of 36 children with bilateral cleft lip, alveolus and palate was studied by means of a frontal proportional cephalometric analysis at the ages of three, eight and twelve years. Comparison of the variables of the cleft group was made with the normal dimensions as obtained from the Bolton cephalometric templates. The results indicated that the BCLP group presented characteristics and significant differences from the normal in the dimensions of the nasal septum width and the mandibular intergonial width as they are both related to the interorbital width, the maxillary intermolar width as it is related to the mandibular intermolar width and the maxillary width as it is related to the mandibular intergonial width at all three ages. The maxillary base and intermolar widths, although significantly different at the ages of three and eight years, showed no significant deviation from normality at the age of twelve years. Following orthodontic treatment between the ages of seven to twelve years, the maxillary intermolar width of the treated subgroup was significantly larger than in the untreated subjects.

Alveolar Process↗
PubMed1988

Dental arch dimensions in patients with unilateral cleft lip and palate.

In this investigation, dental arch dimensions during different ages were studied in 72 children with unilateral cleft of the lip, alveolar process, and palate and were compared with those of normal children. All the children with clefts were treated surgically by surgeons of the Lancaster Cleft Palate Clinic. The dental arch dimensions were studied with the use of dental casts during the time of full deciduous dentition (3 to 4 years of age), mixed dentition (8 to 9 years of age), and permanent dentition (12 years of age). The major findings were: (1) all maxillary interdental widths and lengths were significantly smaller than the normal dimensions at all ages, except for intermolar width at age 12 years; and (2) the mandibular arch dimensions seemed to be related to changes in the maxillary arch; however, the influence of surgical procedures in the maxillary arch is not reflected severely in mandibular arch dental position.

Alveolar Process↗