ABSTRACT
A new machine was developed to study the wear of dental filling materials in vitro. Four products: amalgam, Adaptic, Clearfil and acrylic resin were tested. Wear was measured quantitatively by weighing the specimen, and the wear pattern was studied qualitatively with a scanning electron microscope (SEM). A comparison was made with materials that were placed in the mouth for a prolonged period. It was found that the in vitro wear pattern was comparable to that found in vivo.
Subject(s)
Composite Resins , Resin Cements , Acrylic Resins , Bisphenol A-Glycidyl Methacrylate , Dental Amalgam , Dental Stress Analysis/instrumentation , Equipment Design , Materials Testing/instrumentation , Microscopy, Electron, Scanning , Polymethacrylic Acids , Surface PropertiesABSTRACT
In this study seven commercial composite resins, one experimental composite and one dental amalgam were investigated. These materials were inserted into the cavities of denture molar teeth in different patients. After clinical service for 3, 9, 12, 24 and 54 months the specimens were removed and observed by scanning electron microscopy. The wear patterns of the filling materials and their changes with continuing clinical service for 4.5 years suggest that the abrasive mechanism of conventional composite resin is as follows. The softer resin matrix is worn away and inorganic filler particles are exposed, thereafter they loosen and fall off. As this process proceeds the composite resin is worn away. This process continues with time. In the case of microfilled composite, the organic fillers and resin matrix are worn away at the same rate. After long-term clinical service some cracks could be seen on the wear surface between the organic filler agglomerates and the resin matrix.
Subject(s)
Composite Resins , Chemical Phenomena , Chemistry, Physical , Dental Amalgam , Denture, Complete , Humans , Materials Testing , Microscopy, Electron, Scanning , Middle Aged , Surface Properties , Time FactorsABSTRACT
In the context of a study of the development of enamel lesions in permanent successors of primary molars treated by formocresol pulpotomy, a comparative clinical study was performed of 278 premolars divided equally between test side and control side. These teeth were assessed by two observers who, when finding enamel lesions, always differentiated between opacities and hypoplasias. The principal conclusions from this study are the following: The degree of agreement between the two observers was 96 percent. There was no significant difference in number of teeth with enamel lesions, between test side and control side. When the observed teeth with enamel lesions were related to the age at which pulpotomy was performed, the difference was still insignificant. Separate comparison of opacities and hypoplasias likewise showed no significant differences, even if related to age at which pulpotomy was performed. A formocresol pulpotomy exerts no influence on the size of enamel lesions found in permanent successors of the teeth on which pulpotomies were performed. The general conclusion from the results of this study is that formocresol pulpotomy is a successful technique for the treatment of primary teeth, not only as regards the life-span of these primary teeth (see Part I of the study) but also in terms of its effect on their permanent successors.
Subject(s)
Dental Enamel/abnormalities , Formocresols/adverse effects , Pulpotomy/adverse effects , Root Canal Therapy , Tooth, Deciduous , Age Factors , Child , Child, Preschool , Dental Enamel/pathology , Dental Enamel Hypoplasia/etiology , Female , Humans , MaleABSTRACT
In the context of a study of the life-spans of primary teeth subjected to formocresol pulpotomy, 152 such teeth were compared with the corresponding teeth on the contralateral sides. The life-span of each tooth was determined by registration of the time of exfoliation or extraction. In addition, data were collected concerning factors which may influence the life-spans of teeth. The principal conclusions are: There was no significant difference in life-spans between primary teeth with or without pulpotomy. Premature loss due to extraction exerted virtually no influence on the mean life-span of primary teeth, regardless of whether a pulpotomy had been performed. There was no significant difference in the number of extractions of primary teeth with or without a formocresol pulpotomy. There was no significant difference in the mean life-span between primary teeth with vital and those with nonvital pulp at the time of formocresol pulpotomy.
Subject(s)
Formocresols/administration & dosage , Molar , Pulpotomy/methods , Root Canal Therapy , Tooth, Deciduous , Child , Child, Preschool , Dental Pulp/physiology , Female , Humans , Male , Molar/anatomy & histology , Molar/diagnostic imaging , Periapical Diseases/etiology , Radiography , Time Factors , Tooth Extraction , Tooth, Deciduous/anatomy & histology , Tooth, Deciduous/diagnostic imaging , Toothache/etiologySubject(s)
Dental Caries Susceptibility , Dental Caries/etiology , Oral Hygiene , Saliva/physiology , Adolescent , Child , Child, Preschool , DMF Index , Female , Humans , MaleABSTRACT
gn 137 children whose ages varied from 2-14 years, salivary tests and oral hygiene levels were determined for boys and girls separately. Only the unstimulated flow (flow 1) differed significantly between boys and girls. For the initiation and further development of new caries lesions more precise definitions were used in which the results were corrected for number of teeth present and for the time interval between the observations. The caries scores for all children together were correlated with the several salivary test results as well as with oral hygiene levels. The initiation of caries was correlated with oral hygiene as well as with the Snyder test. The further development of caries correlated almost significantly with the inorganic composition of the saliva alone. No correlation was found between the initiation and the further development of caries.
