ABSTRACT
The kinetic behaviour of dental composite is traditionally studied, considering only the isothermal behaviour, whereas a fast and highly non-isothermal bulk polymerization is expected as a consequence of the significant heat developed due to the exothermic nature of the polymerization reaction. In this paper the photopolymerization kinetics of a commercial dental composite activated by visible light are analysed by differential scanning calorimetry. This technique is applied to determine the degree of reaction and the glass transition temperature of thin layers of the composite matrix, at different isothermal cure temperatures. A phenomenological kinetic model is then integrated with an energy balance in order to analyse the cure behaviour of thicker composite layers. The full model results indicate that non-isothermal cure conditions may be achieved, obtaining higher values for the glass transition temperature and the degree of reaction.
Subject(s)
Composite Resins/chemistry , Dental Materials/chemistry , Polymers/chemistry , Calorimetry, Differential Scanning , Chemical Phenomena , Chemistry, Physical , Hot Temperature , Kinetics , Mathematical Computing , Models, Chemical , Photochemistry , Temperature , ThermodynamicsABSTRACT
The importance of perfect knowledge of the anatomy and physiology of the stomatognathic complex for any understanding of the aetiopathogenic mechanisms behind temporomandibular joint pain dysfunction syndrome is emphasised and the fundamental concepts underlying the use of the bite plane as a valuable aid in the diagnosis and initial treatment of articular dysfunction are described.
Subject(s)
Dental Occlusion , Temporomandibular Joint Disorders/physiopathology , Bite Force , Dental Occlusion, Balanced , Humans , Malocclusion/therapy , Temporomandibular Joint/physiology , Temporomandibular Joint/physiopathology , Temporomandibular Joint Dysfunction Syndrome/physiopathologyABSTRACT
Reference is made to parodontal surgery techniques employing lateral sliding flaps mucogingival for the treatment of gingival schisis. Grupe & Warren (1965) proposed the use of a flap from the parts contiguous to that affected by the schisis. The technique was then developed by the introduction of bipapillar flaps and a flap taken from a toothless saddle. All operations using sliding flaps form part of the most difficult area in mucogingival surgery, due to difficulty of securing the "taking" of the flap on the root cement of the parts affected by schisis.
Subject(s)
Gingivoplasty/methods , Gingivitis/surgery , HumansABSTRACT
Palatine grafts, which today represent the simplest and most reliable technique for enhancing the adherent gum--a problem of great importance in periodontal treatment--are discussed together with other techniques designed for the same purpose. Bone site palatine grafts which restore adherent gum on the alveolar bone, are distinguished from osteo-dental site grafts which are proposed for the treatment of split gums and which only take partially on the radicular surface.
Subject(s)
Gingiva/surgery , Mouth Mucosa/transplantation , Humans , Palate , Periodontal Diseases/surgeryABSTRACT
Examination of 540 Italians indicated that the third molar may form between the 6th and 13th year of life. The statistical possibilities of forecasting agenesis of this tooth at different periods of life are evaluated in this light of the data obtained.