A survey of sodium hypochlorite use by general dental practitioners and endodontists in Australia.

BACKGROUND: Sodium hypochlorite is used commonly as an endodontic irrigant, but there are no published reports that provide details of its use. This survey sought to determine the percentage of Australian dentists who practiced endodontics, whether they used sodium hypochlorite for irrigation, and the manner of dilution, storage and dispensing sodium hypochlorite used by both dentists and endodontists. METHODS: All Australian endodontists and a stratified random sample of 200 general dentists in Australia were surveyed to address the issues identified above. RESULTS: Almost 98 per cent of dentists surveyed performed endodontic treatment. Among endodontists, nearly 94 per cent used sodium hypochlorite for irrigation compared with just under 75 per cent of general dentists. Sodium hypochlorite use by general dentists was more common in Victoria and South Australia than in other States. An infant sanitizer (Milton or Johnson's Antibacterial Solution) was used by just over 92 per cent of general practitioners and by more than 67 per cent of endodontists. All other respondents used domestic bleach. One hundred and sixty four of the respondents (80 per cent of endodontists and over 90 per cent of general dentists) used a 1 per cent w/v solution. Ten practitioners used a 4 per cent w/v solution, five used a 2 per cent w/v solution and four used a 1.5 per cent w/v solution. Eighty per cent of the practitioners who diluted their sodium hypochlorite before use, used demineralized water for this purpose. The remainder used tap water. Only four practitioners stored sodium hypochlorite in a manner which risked light exposure and loss of available chlorine content. CONCLUSIONS: Sodium hypochlorite is commonly used as an endodontic irrigant and Australian dentists generally stored the material correctly.

Pulp-test responses in orthodontic patients.

The diagnosis of orofacial pain is complicated in the orthodontic patient as treatment-induced alterations to pulpal physiology may result in altered responses to pulp-test stimuli. Thirty-three subjects commencing fixed orthodontic treatment and another 15 subjects not undergoing orthodontic treatment were used in this study. Cold and electrical stimuli were applied to the maxillary incisor teeth prior to treatment, after the placement of fixed appliances and at regular intervals for both groups for up to 252 days. At baseline, response thresholds to electric testing were typically higher for orthodontic subjects, particularly for the lateral incisors. For the non-orthodontic group, the response threshold over the 252 days was relatively constant. For the orthodontic group, application of force immediately increased the response threshold to electric pulp testing, which peaked after two months. By day 252, response means for lateral incisors still remained elevated. Responses to thermal testing were more consistent and reliable. The results of this study indicate that dental practitioners should interpret responses to electric pulp testing cautiously in orthodontic patients and that thermal testing with carbon dioxide snow may be more reliable.

Strength decay of orthodontic elastomeric ligatures.

AIM: To evaluate, over a 12-week period, the tensile strength (TS) and extension to TS of elastomeric ligatures (both clear and coloured) obtained from two companies. SETTING: Ex vivo study. METHOD: Seven replicates of five ligatures from two orthodontic companies were tested using an ex vivo assembly which simulated a clinical situation. RESULTS: The ligatures tested had a similar TS decay pattern, with the TS gradually decreasing over the duration of the study. The Unitek ligatures exhibited a greater TS than their respective Ormco ligatures. Generally, all of the ligatures tested experienced an increase in the extension to TS over time. The pre-stretching procedure used in this study did not produce any long-term detrimental effects on the TS and extension to TS of the ligatures tested. CONCLUSIONS: The results of this study confirm there are differences in TS, and extension to TS between clear and coloured elastomeric ligatures, and that some significant differences also exist between different brands of elastomeric ligatures.

The shelf-life of sodium hypochlorite irrigating solutions.

BACKGROUND: Sodium hypochlorite (bleach) solutions are widely used as irrigants in endodontics. Their tendency to deteriorate is worsened by environmental influences which could cause loss of available chlorine content. METHODS: This study measured the loss of available chlorine concentration in a range of sodium hypochlorite solutions under conditions which mimic clinical usage and storage. Domestic bleach, both undiluted and diluted with demineralised water or hard water, was tested, along with Milton, for initial concentration of available chlorine, and then retested after varying periods and modes of storage to measure loss of chlorine concentration. The types of storage were: (1) in closed plastic bottles which were opened daily and agitated; (2) in open plastic bottles; (3) in syringes exposed to sunlight; (4) in syringes kept in the dark; (5) in open stainless steel bowls; (6) in closed stainless steel bowls; and (7) when heated to 50 degrees C. Not all solutions were tested under all storage conditions. RESULTS: Of the solutions opened daily, undiluted domestic bleach was the most stable and Milton was the least stable. Initially, diluted bleach left open deteriorated rapidly but deterioration slowed with time. Solutions in syringes exposed to sunlight showed the most rapid loss of chlorine content. Heated bleach lost nearly 5 per cent of its strength in six hours. Diluted bleach surprisingly, increased its chlorine concentration in open bowls probably due to evaporation of water. Dilution of bleach with hard tap water did not significantly affect shelf-life. Preloading of diluted bleach into syringes appears to be a sound technique if the syringes are stored away from light. CONCLUSIONS: This study reinforces the need for sodium hypochlorite to be stored in closed opaque containers. Constant opening of containers appears to cause greater loss in chlorine concentration of diluted bleach solutions, perhaps because a lower concentration of sodium hydroxide allows the pH to drop more rapidly.