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Biomedical subjects

K M Keenan

Publications and source records attributed to K M Keenan.

At least 19 recordsLinked to original sources
PubMed1996

Comparison of the hearing histories of children with and without cleft palate.

Aggressive otologic management has been recommended for children with cleft palate because of the almost universal occurrence of otitis media with effusion (OME) in these children and the association of OME with hearing loss and possible language, cognitive, and academic delays. In this study, 28 children with cleft palate and 29 noncleft children were seen at 3-month intervals from 9 to 30 months to compare otologic treatment and management. Hearing and middle ear function were tested at each session; information on ventilation tube placement was obtained from medical records. Ventilation tubes were placed earlier and more often in children with cleft palate, but children with cleft palates failed the hearing screening more often. The correlation between age at first tube placement and frequency of hearing screening failures was significant for the children with cleft palate, indicating that the later tubes were first placed, the poorer the child's hearing.

Acoustic Impedance Tests↗
PubMed1994

Evaluation of the ceramic/ceramic interface.

The purpose of this study was to investigate bond strength for ceramic orthodontic brackets bonded to dental porcelain. The following factors were tested. Two types of ceramic brackets were placed on two different types of porcelain surfaces with two different bonding systems. Three different debonding techniques, and various composite removal techniques and surface restoration techniques were used. Two hundred porcelain samples were used that duplicated the labial surface of a maxillary right central incisor. Bond strengths were measured with an Instron Universal testing machine (Instron Corp., Canton, Mass.). Mean bond strength and standard deviations were calculated and significance was determined with analyses of variance (ANOVA) and a chi-square test. Composite removal and polishing methods were investigated by scanning electron microscopy. The results showed that tensile type debonding methods are the least likely to damage the porcelain surface. Some brackets (Unitek Corp., Minn.) having a higher bond strength (p < or = 0.01) fractured the porcelain surface when tested in the shear debonding mode. The bonding materials tested were comparable to adhesion studies of similar brackets to enamel. The Ormco primer-Concise porcelain bonding system was significantly stronger (p < or = 0.01) than the Scotchprime-Transbond. Composite removal by careful use of a carbide bur, followed by the use of the Shofu porcelain adjustment kit and porcelain glaze polish, restored the finish to a normal porcelain surface after debonding. The study showed that shear and tensile debonding forces for glazed porcelain with the use of silane primer, were comparable with those reported in the literature for enamel, thus clinically sufficient. At the same time, preservation of the glaze allowed an almost ideal polishing of the porcelain surface after debonding.

Analysis of Variance↗
PubMed1993

Enzyme activity in crevicular fluid in relation to metabolic control of diabetes and other periodontal risk factors.

Diabetics are generally considered at higher risk for periodontitis than non-diabetics. Among diabetics, those with poorer metabolic control have often been found to have more periodontitis. This study investigated the relationship between two crevicular fluid enzymes, beta-glucuronidase (beta G) and lactic dehydrogenase (LDH), and metabolic control in 93 adults with type 1 or 2 diabetes. Metabolic control was evaluated by glycosylated hemoglobin (HbA1c) levels. The most visibly inflamed site was sampled for crevicular fluid enzymes and plaque for microbial assessment. Plaque, calculus, and probing depth were also recorded. Beta-glucuronidase was found at significantly higher levels in patients with poorer diabetic control while LDH levels were not related to control. Using multiple regression analysis, good metabolic control was the only predicting variable for beta-glucuronidase when considered with microbes, probing depth, plaque, calculus, age, duration, and type of diabetes. If beta-glucuronidase is a predictor of periodontal disease activity, diabetics with poor metabolic control are at higher risk for periodontitis.

Adult↗
PubMed1989

Clinical orodental abnormalities in Mexican children.

A total of 32,022 Mexican children (16,473 boys, 15,549 girls) were examined for several congenital oral and paraoral anomalies. The findings for commissural lip pits (boys 53.1, girls 52.4 per 1000) are less than those reported for adults. This may indicate that pits become accentuated with age. Fordyce granules were seen with a prevalence of 1.2 per 1000. This is in contrast to the reported 85.6% prevalence for the adult population, also possibly reflecting increased manifestation with increased age. Our data for exogenous tooth pigmentation show increased prevalence with age (group I [5 to 10 1/2 years], 9.8%, versus group II [10 1/2 to 14 1/2 years], 12.9%), possibly indicating decrease in attention to oral hygiene. The prevalence of talon cusp was found to be 0.6 per 1000, and for ankyloglossia 8.3 per 1000. Prevalence values for bifid tongue are reported for the first time, indicating one affected per 187 children examined. The prevalence of fissured tongue (15.7%) shows a statistically significant difference between boys (16.8%) and girls (14.5%). The prevalence of geographic tongue (1.9%) shows a marked difference between group I (2.2%) and group II (1.2%).

Adolescent↗
PubMed1989

The effects of temporomandibular joint internal derangement and degenerative joint disease on tomographic and arthrotomographic images.

In a blind study, 243 arthrograms were interpreted as showing normal disk position, anterior disk displacement with reduction, or anterior disk displacement without reduction. The presence or absence of a perforation of the posterior attachment or disk was recorded. Later, tomograms of the same patient were interpreted. The presence or absence of evidence of temporomandibular degenerative joint disease (TMDJD) was recorded. The condyle-to-fossa relationship was characterized as retropositioned or not retropositioned. O the 106 cases with tomographic evidence of TMDJD, 100 (94%) had arthrographic evidence of internal derangement (p less than 0.0001), whereas 47% of the cases with internal derangement (211) had evidence of TMDJD. Perforations were seen in 29 (27%) of the cases with degenerative joint disease and in none (0%) of the cases without TMDJD (p less than 0.001). In cases without TMDJD, 90% of the cases with internal derangement revealed condylar retropositioning (p less than 0.0001). With tomographic evidence of TMDJD present, the relationship between condylar position and disk position was not significant.

Arthrography↗
PubMed1989

Condylar position as a predictor of temporomandibular joint internal derangement.

Scout tomograms and arthrograms of 243 patients were separated and numbered. The location of the condyle within the fossa in the closed-mouth position was assessed by means of three evaluation techniques. Later, the arthrograms were interpreted and matched with the corresponding tomograms to evaluate the relationship between posterior displacement of the condyle and anterior displacement of the articular disk. The position of the disk within the fossa was found to be extremely variable whether disk position was normal or abnormal.

Arthrography↗
PubMed1989

Standardized panoramic radiography in assessment of mandibular augmentation with hydroxylapatite material: preliminary report.

This study evaluates the usefulness of a head-positioner/cephalostat in producing standardized panoramic radiographs by assessing the reproducibility of the radiographs and comparing the standardized panoramic radiographic findings with those obtained from 45 degrees right and left lateral cephalograms. Comparison of measurements indicated that this cephalostat produced reproducible panoramic radiographs. Measurements on each panoramic radiograph showed standard deviations ranging from 0.0 to 0.24 mm (pooled SD = 0.12), whereas the SDs for the 45 degrees lateral cephalograms ranged from 0.0 to 0.45 (pooled SD = 0.14). This indicates that the panoramic radiographs obtained with this head-positioner/cephalostat were comparable to those obtained by 45 degrees lateral cephalograms.

Alveolar Process↗
PubMed1988

Taurodontism: an anomaly of teeth reflecting disruptive developmental homeostasis.

Two models concerning morphometric traits occurring frequently in aneuploidy states posit, respectively, 1) that they reflect the expression of specific major oligogenes for that trait on the chromosome involved or 2) that they result from a generalized disruption of developmental homeostasis. In contrast to previous studies that have investigated variations in morphometric traits in a single aneuploidy state, this study investigates a single morphometric trait, taurodontism, as it occurs in otherwise normal individuals, in nonchromosomal syndromes, and in aneuploidy syndromes to determine whether the trait best fits the oligogene or the disrupted developmental homeostasis model. Taurodontism is diagnosed from dental radiographs. It is an extreme variation in tooth form seen in multirooted teeth in which the bifurcation or trifurcation of the roots is displaced toward the apex of the root, resulting in increased size of the pulp chamber. The point of furcation, and consequently the size of the pulp chamber, is a quasicontinuously distributed trait. The results indicate that taurodontism most likely is the result of disrupted developmental homeostasis.

Adolescent↗
PubMed1987

Elevated urinary dolichol excretion in the Hermansky-Pudlak syndrome. Indicator of lysosomal dysfunction.

The Hermansky-Pudlak syndrome, a triad of albinism, platelets lacking dense bodies, and storage of ceroid-like material in tissues, occurs approximately once in 2,000 northwestern Puerto Ricans. The manifestations of storage disease are variable and include granulomatous colitis, restrictive lung disease, kidney failure, and cardiomyopathy. The autofluorescent material stored in the Hermansky-Pudlak syndrome is histochemically similar to that stored in neuronal ceroid/lipofuscinosis. The material in neuronal ceroid/lipofuscinosis contains dolichols, which are components of lysosomes, and patients show increased urinary excretion of dolichols. This study of 49 patients with the Hermansky-Pudlak syndrome found that urinary dolichol levels are increased in those patients with evidence of ceroid storage in the kidneys but are not elevated when storage occurs in tissues other than the kidneys. The excretion of ceroid was not influenced by the saturation state of dietary fat. A defect in processing of membranes of lysosomes, melanosomes, and dense bodies may be involved in the syndrome.

Albinism↗
PubMed1984

Surgical cautery revisited.

A new hemostatic scalpel has been developed to control bleeding between the cut edges of wound tissue. The scalpel blade resembles conventional scalpel blades, except that it can be heated and its temperature controlled within narrow limits. Cutting is accomplished by the blade's sharp edges, and hemostasis results from the direct transfer of heat from the blade to the tissue. This experimental study has demonstrated that the hemostatic effect of the scalpel is associated with damage to the tissue's defenses against infection and impaired wound healing.

Animals↗
PubMed1983

Relationship between proximal tooth open contacts and periodontal disease.

ONE HUNDRED FOUR adult subjects (mean age 42.8 years, SD = 16.3 years) with unilateral open contacts were assessed interproximally for periodontal status at both the open and contralateral closed contact. An open contact was defined by unrestricted passage of unwaxed dental floss through the interproximal area. Gingival index, crevicular bleeding, probing depth, attachment level, debris, calculus and tendency for food impaction in each study area were recorded. Less debris was seen at open contacts (P less than 0.001). However, increased probing depth (0.27 mm, P = 0.002) and attachment loss (0.48 mm, P less than 0.001) were found at the open contacts. Small but statistically significant relationships were observed between side to side differences in food impaction and both probing depth (P = 0.005) and attachment level (P = 0.006). Differences in calculus index and attachment level were associated similarly (P = 0.003).

Adult↗