Methods for evaluation of working and setting times of periodontal dressings.

Three different methods were used to determine working and setting times of periodontal dressings. The Gillmore needle and the rheometer employed were not suitable for recording setting reactions. A penetration test was found applicable for determination of working and setting times for all three dressings although they exhibited different setting characteristics.     

Plunging or cervical ranula. Review of the literature and report of 4 cases.

A review of the literature pertaining to plunging ranula is presented with special emphasis on the historical development of the various aetiological theories and treatment recommendations. Also 4 cases of plunging ranula are presented; three were treated by extirpation of the sublingual gland and one was treated by exteriorization of the ranula into the oral cavity. The treatment methods used here are discussed in relationship to the accepted aetiological theory.     

A study of the viscosity of saliva at different shear rates in dentate and edentulous patients

A Wells-Brookfield microviscometer was used to measure the viscosity of saliva from dentate and edentulous individuals at shear rates ranging from 1·15/s to 230/s. The advantages of using such an instrument are discussed in the light of the recognition of saliva as a viscoelastic fluid exhibiting non-Newtonian viscosity. The viscosity of saliva of the dentate group was found to be significantly higher than that of the edentulous group at shear rates above 1l·5/s. It is suggested that these differences may be related to the mucin content of saliva.     

Do self-curing acrylic resin repairs gain strength with age?

The effect of age on the strength of self-curing acrylic resin repairs has been investigated. Several other properties which may be related were also studied. The findings indicate that the strength of a repair increases with time, attaining a significant proportion of its final strength by 24 hours and reaching a maximum between 1 day and 1 week.     

The role of xeroradiography in cephalometric radiology.

The advantages of xeroradiography in the precise identification of anatomical landmarks for orthodontic analysis are overwhelming. In addition, the soft tissues of the face are shown fully and in detail. The tongue and soft palate can also be visualized. However, there is undue anxiety among clinicians and radiologists about the risk of excessive radiation exposure to patients. This has hitherto been regarded as unavoidable for the purposes of xeroradiography.This paper sets out in detail the advantages of xeroradiography for cephalometry and also clarifies the problem of patient exposure by presenting detailed measurements of the parameters affecting exposure and of the incident skin exposure. In this way it can be shown that by choice of correct kilovoltage and adequate filtration the incident skin exposure can actually be reduced when compared with conventional techniques using film.