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Biomedical subjects

D Stom

Publications and source records attributed to D Stom.

6 recordsLinked to original sources
PubMed2002

Bioluminescence assays: effects of quinones and phenols.

The influence of a series of quinones and phenols on bacteria bioluminescence systems was investigated. Three bioluminescence systems used in ecological monitoring were compared: (1) water-soluble; (2) immobilized in starch gel coupled enzyme systems: NADH:FMN-oxidoreductase-luciferase; (3) luminescent bacteria. Bioluminescence inhibition constants of quinones and phenols and bioluminescence induction periods were compared. These kinetic parameters are proportional to quinone concentrations and depend on the quinone redox potential. Different effects of the substances are related to structure and properties of the bioluminescence systems. The set of bioluminescence assays for quinones and phenols monitoring should include two bioluminescence systems: 1 (or 2) and 3.

Environmental Monitoring↗
PubMed1996

Bringing impacted mandibular second premolars into occlusion.

Impaction of the mandibular second premolars is relatively rare and may offer general dentists and orthodontists special challenges during treatment. The authors discuss two cases involving impacted mandibular second premolars that had migrated before eruption. Surgical and orthodontic therapies were used to bring the teeth into occlusion. The authors emphasize early diagnosis and a collaborative approach between the dental professionals involved in treating these affected patients.

Adolescent↗
PubMed1989

Maxillary canine-lateral incisor transposition--orthodontic management.

A case of maxillary canine-lateral incisor complete transposition is presented. Treatment options for transposed teeth, including alignment in their transposed positions, extraction of one or both transposed teeth, and orthodontic alignment to their normal positions in the arch, are discussed. The orthodontic technique and sequence used in this challenging case to align the fully transposed teeth to their normal position in the dental arch are described.

Child↗
PubMed1981

A biometric study of tooth size and dental crowding.

A study was conducted for the purpose of comparing mesiodistal tooth widths between a group of patients with good tooth alignment and a group of patients with crowded dental arches. Crowded arches were defined as those with more than 4 mm. of space deficiency. The hypothesis tested was whether the arches with more than 4 mm. of crowding consistently had larger teeth than the ones with lesser or no crowding. The difference in sizes between the groups (forty males and forty females) for all teeth measured was found to be statistically significant (p less than 0.001). The multivariate data analysis indicated that the two groups were derived from two different populations and that the maxillary lateral incisors and second premolars and the mandibular canines and premolars were particularly different in these groups. It was also determined that the teeth in males were uniformly larger than in females, but not to a statistically significant level. There was less correlation, however, between the sex and the status of the tooth alignment in dental arches, so that both sexes had similar distribution of crowding versus noncrowding. On the basis of this study of eighty North American Caucasians, it is suggested that one should consider the sum of mesiodistal widths of teeth, in addition to the arch length analysis, in formulating an orthodontic treatment plan. When the cumulative tooth mass of the twenty permanent teeth is 140 mm. or more, the clinician may want to consider extraction therapy for such a case.

Adolescent↗
PubMed1975

Effect of edgewise treatment and retention on manidbular incisors.

This study consisted of analyzing clinical records of fifty cases treated for correction of Class I malocclusion with varying degrees of bimaxillary protrusion and anterior mandibular crowding. Thrity of these cases required extraction of all four first premolars. Parameters characterizing changes in position of mandibular incisors during treatment with edgewise appliances and during retention and shortly afterward were studied. All the parameters indicated rather similar changes for the nonextraction and the extraction groups. The relapse of anterior mandibular crowding was significantly larger (p less than or equal to 0.05) in the nonextraction group. The IMPA and interincisal angle changed significantly more in the extraction group. Upon testing for validity of the mesiodistal to faciolingual indices, it was determined that they predicted stability of the achieved alignment of mandibular incisors. There were, however, individual cases in both groups which did not follow the central tendency. It was observed that the mesiodistal diameters of mandibular incisirs were somewhat larger in the extraction cases. There was only one pair of parameters that showed a moderately high intercorrelation (r equals 0.68); that was between correction of the anterior crowding and relapse of the intercanine expansion. It was observed that the more correction took place, the more readily expanded canines would relapse. An over-all impression is that the mandibular incisors change little in their position to each other and relative to the other structures of the mouth. The question remains: Is this due to our ability to control them well, or due to an inability to move and maintain them in their new position?

Bicuspid↗