Journal of Orthodontics

This article adds to the literature available on Pericision. In its introduction it endeavours to explain to those who have not used the technique the development of thought and experimental evidence on the subject. It adds to and supports the figures of Pinson and Strahan (1973) and Mills and Strahan (1970). As the actual work was carried out in 1971–72 when little clinical evidence was reported the series includes cases where retention varied from none at all to 20 weeks. Results where fixed as against removable retainers were used are compared. It concludes by tentatively advising adoption of the technique as a routine clinical Procedure provided fixed retainers are used and retention is continued for at least 15 weeks.

Facial proportions are important from an aesthetic point of view in that to be harmonious the upper, middle and lower face need to be of approximately equal size.

The object of this study is to determine changes in hard and soft tissue profile which occur in patients having a Class II, Division 1 type incisor relationship as a result of overjet reduction.

Thirty-three patients were studied cephalometrically there being an average overjet of 6·99 mm at commencement of treatment which reduced to an average of 3·5 mm on final analysis.

Clinical appraisal suggests that there was an improvement of facial appearance following treatment. Cephalometric analysis shows that subnasale, labrale superius and labrale inferius moved nearer to the facial Plane as a result of re-modelling of the hard tissues resulting from orthodontic treatment.

The female patients showed a relationship between retraction of the upper incisors and reduction in prominence of the lower lip and in those having a Class I dental base relationship, prominence of the upper lip. The male patients showed no correlation between upper incisor position and lip position. Continuing mandibular growth in the male could have a bearing on these findings.

This is the last of a three part article. In the first part the author reviewed the history of edgewise bringing it up-to-date with a description of the Progressive Light Wire Edgewise technique.

In Part II he continued to compare and contrast the Progressive Light Wire Edgewise technique of Ricketts with other techniques. He described three cases to illustrate the basic principles involved in this light edgewise technique.

In Part III the cephalometric diagnostic technique which Dr Ricketts started to develop before he introduced the Light Progressive Edgewise technique is brought up-to-date. The author describes the treatment of a case. The sophisticated cephalometric diagnostic procedures used by the Ricketts' school is outlined. The treatment of the case by the Progressive Light Edgewise technique is illustrated. The presentation of this third part is intended to emphasize that both the sophisticated cephalometric diagnostic procedures and the mechanical approach to treatment, which have been developed by Dr Ricketts, lead to a very efficient and highly individualized approach to orthodontic treatment and facial rehabilitation when used in harmony with one another.

The construction of a phantom head for demonstrating extra-oral traction is described. It has been found useful when showing students the effect of different designs of head gear and when explaining the purpose and action of headgear to patients and parents.

An investigation is described into mandibular growth in the Dog (Canis familiaris). The growth Patterns were identified by the use of the fluorescent intra-vital bone marking dye Di-Carboxymethyl Amino-methyl Fluorescein. The outlines of structures found in serial sections cut from the jaws were recorded in a numerical form on punched paper tape by tracing on an electronic X-Y co-ordinate plotting table. A series of computer programmes were developed to use the data on the paper tapes to assemble three dimensional reconstructions of the original jaws in the memory store of a computer. The reconstructions were stored on magnetic tape and used for subsequent analysis and measurement. Mandibular growth was studied in three Ways. First by computer drawn plots of the original sections. Secondly by computer derived longitudinal plots of jaw structure. Finally by measurement of the volumes of the jaws, the structures within the jaws, and of the bone laid down during the experimental period.

The method of assessing the skeletal pattern from a correction of incisor inclinations is subjected to critical review. It is concluded that the method does not have a sound basis and that it should be abandoned.

Considerable interest has been shown in the method of bonding orthodontic attachments directly to the tooth surface eliminating the use of bands. Many orthodontists are using this technique routinely in clinical practice, and most orthodontic supply houses now produce some form of “bonding kit”. This article aims to present a background, against which the present usage of the technique can be assessed.

In vitro studies of the tensile bond strengths of a zinc polycarboxylate cement and an unfilled diacrylate resin to stainless steel have been performed. The zinc polycarboxylate cement was found to exhibit good adhesion to stainless steel. However, the diacrylate resin adhered poorly to the stainless steel. This was probably due to the poor wetting of the stainless steel by the diacrylate resin. The clinical implications of these observations are discussed.