Biomedical subjects

C J Stock

Publications and source records attributed to C J Stock.

At least 19 recordsLinked to original sources

PubMed1992

A comparison in vitro of two ultrasonic root canal preparation techniques.

Two ultrasonic techniques were compared for their ability to clean and shape root canals in extracted human teeth. One technique was recommended by the manufacturer (Cavi-Endo, Dentsply), while the other was a modification by the authors of the stepdown technique. Mesiobuccal root canals of molars were instrumented using these techniques, after which a silicone impression material was injected into the prepared canals. The roots were then split longitudinally and one half was stained for debris scoring while the silicone impressions were assessed for shape. The results showed that the modified technique produced significantly cleaner canals than the recommended technique. The shaping ability of both techniques was difficult to evaluate because of the complex morphology of molar root canals. The final shape of the prepared canal depended more on the initial shape than on the instrumentation technique.

Dental Cavity Preparation↗

PubMed1991

Endodontics in the UK 1990: an overview.

The first workshop on endodontics, in 1978, pointed out that the standard of endodontics in the United Kingdom was poor. The British Endodontic Society has subsequently attempted to improve the remuneration in the NHS by conducting and publishing a survey, and also establishing guidelines for minimum acceptable standards. Despite this, in the author's opinion, there has been no improvement. However, four ways of raising the standards of endodontics are proposed.

Education, Dental↗

PubMed1991

Organizing a postgraduate course.

The running of a section 63 hands-on course on endodontics requires prior planning. Suggestions on how to plan such course include the design of the programme, the number of course members and instructors, requirements from the postgraduate centre, equipment and materials needed, travel and accommodation, and finally reimbursement.

Education, Dental, Continuing↗

PubMed1991

Safe use of codeine in the recovering alcoholic or addict.

The effect that codeine has on the process of addiction and recovery is unclear. Confusion about definitions, study endpoints, and a lack of well-controlled clinical studies has led to this uncertainty. Codeine addiction is uncommon in people who do not have existing vulnerability to addiction, including alcoholism. Codeine use can sustain addiction or increase the risk of relapse in patients afflicted with addiction. The risk of relapse must be considered when treating conditions such as pain or cough in a person recovering from addiction. Codeine use may be circumvented with the appropriate use of alternative treatments for pain or cough. If codeine use becomes necessary, cautious prescribing and reliance on the patient's recovery support network become imperative.

Alcoholism↗

PubMed1991

Current status of the use of ultrasound in endodontics.

Although endosonics has received much attention in the literature, it is not clear whether it is recommended. This review discusses the types of endosonic unit available, ultrasonic phenomena such as cavitation and acoustic streaming, irrigation, cutting dentine, and clinical techniques for cleaning and shaping. The more recent evidence suggests that endosonics provides an efficient method of debridement providing sodium hypochlorite is used, but is less efficient at shaping the walls of the canals. New methods of filing have been introduced by the manufacturers but they have not taken into account the most recent research; for this reason an alternative approach is described.

Humans↗

PubMed1989

An in vitro method for comparing the effects of different root canal preparation techniques on the shape of curved root canals.

This study introduced an in vitro model which was designed to observe the effects of instrumentation on the shape of curved root canals. The model may be accurately rotated through 90 degrees allowing reproducible radiographs to be taken from two different angles. The root canals were filled with a radiopaque contrast medium before radiographs were taken. Two-dimensional evaluation of the shape of the root canals, before and after preparation was made on enlarged photographic prints obtained from the radiographs. A custom-made grid was used as a guide for measurement and accurate transfer from the pre- to postpreparation prints. Reproducibility of measurement was within 4 per cent. This method is feasible for quantitative comparison of the effect of instrumentation on the shape of root canals.

Dental Pulp Cavity↗

PubMed1989

The effect of hand, sonic and ultrasonic instrumentation on the shape of curved root canals.

This study compared the effects of hand, sonic and ultrasonic instrumentation on the shape of curved root canals in 60 extracted human lateral incisors and premolars. Each root of moderate or severe canal curvature was mounted onto a simulated crown and filled with a radiocontrast medium. Enlarged photographic prints obtained from radiographs taken before and after root canal preparation were measured. The results indicated a lower incidence of apical zip and elbow formation in the ultrasonic preparations when compared with those prepared by hand and sonic, irrespective of the canal curvature. A more prominent hour-glass shape was prepared by hand and sonic instruments particularly in severely curved root canals. A distinctive taper was produced by each method of preparation. All three instrumentation techniques showed preferential dentine removal from the convex aspect of the canal in the apical portion and the concave aspect in the middle portion of the root canal.

Dental Pulp Cavity↗

PubMed1989

An in vitro comparison of ultrasonic and conventional methods of irrigant replacement.

The effectiveness of irrigant replacement in fine canals was compared using three sizes of irrigating needle and an ultrasonic method. The results showed that irrigant replacement became progressively less effective towards the apex regardless of the method of irrigation or needle size. With conventional methods, irrigation performance varied with the size of needle and volume of irrigant. With the ultrasonic method results depended on irrigation time, but was independent of irrigant flow rate through the handpiece, the size of the canal or the file size.

Root Canal Irrigants↗

PubMed1989

Dentine-removing characteristics of an ultrasonically energized K-file.

This in vitro study evaluated the pattern of dentine removal when an ultrasonically energized file (Cavi-Endo-size 25 file) was applied to flat surfaces of dentine under standardized conditions. The influences of power setting, interfacial force between file and dentine, direction of file oscillation and operator-assisted movement were examined. Impressions of the instrumented surfaces revealed characteristic patterns consisting of a series of oblique crests, each one parallel to the next and separated by a constant distance along the line of contact with the file. Determination of height, width and separation of these crests with a Reflex microscope aided objective assessment. The simplest pattern was formed when the energized file was held against the dentine (power setting = 1; interfacial force = 30 g). Increasing the power setting to 8 caused deeper troughs over the apical 5 mm. The width of the crests corresponded to the taper of the file except at the apical tip where the crests were relatively wider. However, increasing the interfacial force to 60 g reduced the efficiency of the apical part of the file. The superimposition of operator-induced movement greatly increased the extent of dentine removal, resulting in a tapering groove with a persistent crestal pattern. Oscillation of the file perpendicular to the dentine surface had a significantly greater influence on dentine removal, producing a deeper groove than was obtained with oscillation parallel to the surface. These findings may be of relevance in aiding controlled root canal preparation when using the Cavi-Endo instrument.

Dental Cavity Preparation↗

PubMed1989