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Biomedical subjects

L C Martens

Publications and source records attributed to L C Martens.

13 recordsLinked to original sources
PubMed1991

Compressive strength of some polyalkenoates with or without dental amalgam alloy incorporation.

The present study compares the compressive strength after one week of some conventional glass-ionomer restorative materials with that of glass ionomers reinforced by the addition of ceramic-coated silver or dental amalgam alloy particles to the aluminosilicate glass powder. Apart from the commercially available Ketac Silver and Miracle Mix, experimental mixtures of Fuji II glass-ionomer powder, the old as well as the new version, with various amounts of either a spherical or lathe-cut amalgam alloy were investigated. For the conventional glass ionomers, the mean compressive strength based on all measurements amounts to 159.9 +/- 4.5 MPa. Both formulations of Fuji II have a comparable strength after one-week maturation. The compressive strength of Ketac Silver does not differ significantly from that of Ketac Fill or from that of the conventional glass ionomers investigated. The effect of admixing amalgam alloy on the compressive strength is found to be determined by the shape and the amount of the alloy particles. Moreover, both parameters are interactive with the formulation of the Fuji glass ionomer used for preparation of the mixture. The results indicate that when dental amalgam alloy is added to the glass ionomer, lathe-cut particles are to be preferred but only in an amount up to 20% by weight.

Analysis of Variance↗
PubMed1989

[Avulsed teeth. A case study].

A clinical case of exarticulation and replantation served to discuss recent insights regarding the treatment of total avulsions of permanent teeth. A flow chart representing all treatment options is given. The tooth has been replanted in near ideal conditions; within one hour after the avulsion, the young patient attended the dental school with his avulsed tooth stored in milk. After replantation, a very simple splint was applied for only a fortnight and a provisory endodontic therapy with calcium hydroxide was performed. Adequate oral hygiene measures supported with chlorhexidine gel were instructed. These promote the healing process and ultimately also contribute to a long-term survival of the replanted tooth. After healing, a permanent root canal filling was applied and the crown was restored by means of composite material. The one-year- follow up check did not show any sign of resorption and/or ankylosis.

Child↗
PubMed1987

The contribution of CO3(3-) and CO2- to the ESR spectrum near g = 2 of powdered human tooth enamel.

The ESR spectrum near g = 2 of powdered human tooth enamel from upper central incisors and lower canines was studied as a function of microwave power, irradiation, and storage time. The results clearly demonstrate that the ESR spectrum is composite with at least five paramagnetic species contributing to the signal. The main stable component is assigned to CO2-. Two other components arise from CO3(3-) radicals, one of which is demonstrated to be the same center as is present on a phosphate site in sodium- and carbonate-containing calciumapatite.

Carbonates↗
PubMed1986

The microcrystal alignment in human tooth enamel from carious and non-carious teeth in relation to caries susceptibility.

The degree of microcrystal alignment in the intact enamel from carious and non-carious upper incisors, lower incisors and upper canines was determined by means of electron paramagnetic resonance. The results show that a low degree of alignment is not a generally valid indication for caries-susceptibility. Upper canines have a high degree of crystallite alignment whereas lower incisors have a relatively low one. With the exception of the upper central incisors no differences in microcrystal alignment are found between the intact enamel from carious and non-carious lower incisors and upper canines. These results indicate that a possible caries-susceptibility of tooth enamel reflected by low R-values is not solely determined by the degree of microcrystal alignment.

Crystallization↗
PubMed1985

Apatite crystallite alignment in sound human tooth enamel studied by E.S.R.

The degree of microcrystal alignment in enamel of clinically sound upper and lower central incisors, canines and premolars was determined by means of electron paramagnetic resonance. The results show that the degree of alignment depends on the individual properties of the enamel as determined by biological variations, tooth morphology and tooth position. Upper incisors and canines have a much higher degree of crystallite alignment as compared to all other teeth investigated. These results indicate that the caries susceptibility of tooth enamel is not defined only by the degree of microcrystal alignment.

Apatites↗
PubMedDate not supplied

Effect of anti-sensitive toothpastes on opened dentinal tubules and on two dentin-bonded resins.

Treatment of dentin hypersensitivity will become of increasing importance in the daily practice of dentistry. The goal of any therapy should be the closure of opened dentinal tubules. The present study made an SEM evaluation of the effect of anti-sensitive toothpastes on root dentin with regard to the superficial changes and possible penetration by toothpaste particles. Further, the study performed an evaluation of the wear-resistance of two dentin-bonded resins during brushing, using the same anti-sensitive toothpastes. Having induced coverage of the dentinal tubules with the toothpastes (Sensodyne, Emoform and Macleans Sensitive), no particles were found within the tubules. The application of dentin-bonded resins seems an alternative solution for treating dentin hypersensitivity.

Acrylic Resins↗
PubMedDate not supplied

A clinical evaluation of a light-cured fissure sealant (Helioseal).

The clinical success of pit and fissure sealants has been reported by several authors. In this study a white-shaded, visible-light-cured sealant was used; the results of the clinical evaluation confirmed this finding. Concerning retention rate, marginal adaptation, and the presence of secondary caries and air bubbles, good results were obtained. Data indicate that a visible- light-cured sealant (Helioseal) appears to be as good as the self-cured sealants and better than the UV-light-cured products. A comparison was also made between the invasive (PFSI) and non-invasive (PFS) application techniques; with respect to the marginal adaptation and the presence of air bubbles, better results were found for fissures that had been enlarged as a preventive measure. More longitudinal studies over a longer period of time are necessary.

Adolescent↗
PubMedDate not supplied

Root surface caries: an update.

Root surface caries lesions will become more predominant in the future. Recently, several definitions and graduations have been suggested. Objective, epidemiologic data are still lacking. The etiologic factors of root surface caries generally are parallel to those of coronal caries. However, some nuances needed to be identified. Differences concerning the bacteriologic characteristics, the substrate, the mineral composition, and the clearance are discussed. Some patients are more likely to develop multiple lesions than others. Restorative materials with bonding abilities to dentin are the preferred materials. Fluoride applications will probably be the most effective in preventing the development of root surface caries lesions.

Dental Caries↗