'It's good enough': Swedish general dental practitioners on reasons for accepting substandard root filling quality.

AIM: The concept of 'good enough' is central and necessary in the assessment of root filling quality. The aim was to explore the concept by analysing reasons and arguments for the acceptance or rejection of substandard root filling quality as reported by general dental practitioners (GDPs) in Sweden. METHODOLOGY: The study was designed as a qualitative and exploratory study based on seven videotaped focus group interviews analysed by means of qualitative content analysis. Thirty-three GDPs employed in the Public Dental Health Service in Gothenburg, Sweden, participated (4-6 GDPs/interview). In all, nine predetermined questions were followed. Before each focus group, the participants received radiographs of 37 root fillings and were asked to assess the root filling quality. The three cases representing the most divergent assessments served as a basis for the discussion. The cases were presented without clinical information; the dentists would relate to the cases as being just root filled by themselves. RESULTS: The radiographs did not provide a sufficient basis for decisions on whether or not to accept the root filling. This study emphasized that dentists did not primarily look for these arguments in the technical details of the root filling per se, but instead, they considered selected features of the contextual situation. The GDPs constantly introduced relevant 'ad hoc considerations' to account for the decisions they made. These contextual considerations were related to aspects of pulpal and periapical disease, risks (e.g. technical complications) or to consumed resources (personal and/or economic). CONCLUSIONS: It was obvious that the concept of 'good enough' does not exist as a general formula ready to be applied in particular situations. Instead, it is necessarily and irremediably tied to contextual properties that emerge from case to case.

'Working in the dark': Swedish general dental practitioners on the complexity of root canal treatment.

AIM: To explore elements of reasoning and understanding that might obstruct the performance of good-quality root canal treatment (RCT) and make general dental practitioners (GDPs) produce and accept root fillings of inferior quality. METHODOLOGY: The study was designed as a qualitative and explorative study based on seven videotaped focus group interviews analysed by means of qualitative content analysis. Nine predetermined questions were followed. Thirty-three GDPs (4-6 dentists/interview), employed in the Public Dental Health Service in Gothenburg, Sweden, participated. RESULTS: Feelings such as anxiety, frustration, stress or exhaustion were associated with RCT. In general, RCT was regarded as complex, mysterious and embedded in uncertainty. A feeling of loss of control was frequently described in relation to all procedural steps from negotiating the canal to prognostic deliberations. Reasons could include challenging canals, complicated instruments and the fact that treatment had to be performed in a concealed space without visible insight. Several dentists questioned the requirements for correctly performing RCT, and some indicated that striving towards optimal technical root filling quality should not be expected in each case in general practice. Most of the GDPs were unable to complete a case within the remuneration system, and they therefore either spent more time than the set fee allowed for or accepted a suboptimal root filling when the time limit was reached. CONCLUSIONS: High levels of stress and frustration in relation to RCT were reported by the GDPs. RCT was regarded as complex and was often performed with an overall sense of lack of control.

The impact of a continuing education programme on the adoption of nickel-titanium rotary instrumentation and root-filling quality amongst a group of Swedish general dental practitioners.

INTRODUCTION: The aim of the study was to test the hypothesis that a further education programme relating to nickel-titanium rotary instrumentation (NTRI), with the concurrent activation of social/professional networks amongst all general dental practitioners (GDPs) in a public dental service in Sweden, would increase the adoption rate and improve root-filling quality. MATERIAL AND METHOD: To activate the networks, the GDPs at the 25 clinics elected training coaches from amongst themselves. The coaches were educated by a specialist and were then free to organise and conduct the training of the local GDPs. However, collective hands-on training and discussions were mandatory. Lectures were held by an endodontist. The rate of adoption and root-filling quality was evaluated just before and 6 months after the education. Statistical tests were performed with chi-square using a 95% confidence interval. RESULTS: Nickel-titanium rotary instrumentation was adopted by 88%. Excellent root fillings (score 1) increased from 45% to 59% (P = 0.003). The rate of poor-quality root fillings (score 4 and score 5) was not affected. The quality ratio (score 1/score 5) increased from 5.36 (118/22) to 9.5 (133/14). Eleven dentists (17%) at nine different clinics produced 49% of the poor-quality root fillings (score 4 and score 5). Seventy-three per cent of these dentists stated that they had adopted NTRI. CONCLUSIONS: The introduction of NTRI will increase the adoption rate and the frequency of good-quality root fillings. However, it will not overcome the problems associated with dentists producing a low-quality level, even if a local professional network is activated.

Endodontic malpractice claims in Denmark 1995-2004.

AIM: To study the reasons for and outcome of malpractice claims handled by the regional and national Danish Dental Complaint Boards (DCB) from 1995 to 2004. Specific attention was paid to endodontic claims. Three hypotheses were explored: endodontic malpractice claims are frequent, they are mostly due to technical shortcomings and male dentists are overrepresented. METHODOLOGY: The reasons for the claims were classified and assigned to at least one of 14 categories. Cases assigned to the 'endodontic treatment' category were further sub-categorized, and reasons for malpractice were examined. An age and gender analysis of dentists and complaining patients was performed only on data obtained from the endodontic cases. RESULTS: Overall, 3611 malpractice claims were registered. In 43% of the cases the dentist was judged to be guilty of malpractice. In the majority of the appealed cases the original verdict was affirmed (62.2%) by the national DCB. After crown & bridge treatment (23%) endodontic treatment was the next frequent malpractice claim (13.7%), in which 'technical complications or incorrect treatment' was the most frequent sub-categorization (28.4%). Reasons for endodontic malpractice verdicts were related to root filling quality, the use of a paraformaldehyde product and instrument fracture. Male dentists were most often involved in an endodontic claim, and the majority of complainants were females. CONCLUSIONS: Endodontic malpractice claims were relatively common in Denmark. Perceived technical shortcomings dominated the patients' complaints concerning root canal treatment. Male dentists and female patients were overrepresented indicating a gender influence on aspects of the doctor-patient communication important for liability claims.

A preliminary study on the technical feasibility and outcome of retrograde root canal treatment.

AIM: To investigate the technical feasibility and outcome of retrograde root canal treatment. SUMMARY: Endodontic access cavity preparation in abutment teeth may jeopardize the retention of the coronal restoration leading to prosthodontic failure. In such cases leaving the crown intact and performing retrograde root canal treatment might be an alternative approach. The potential to promote healing with retrograde endodontic treatment, and the technical feasibility to shape, clean and fill the canal was evaluated retrospectively. The study consisted of 21 incisors, canines and premolar teeth followed-up clinically and radiographically from 6 to 48 months. In 14 teeth the canals were completely negotiated. These cases were all judged as completely healed. In five cases no canal could be explored by files and a conventional ultrasonic root-end preparation and filling was performed. Two of these were classified as completely healed and three as 'uncertain'. In 2 two-rooted premolars a combination was performed with complete instrumentation of the buccal canal and the ultrasonic root-end preparation of the palatal root. One case was judged as a failure and the other was classified as completely healed. The results from this preliminary evaluation of retrograde root canal treatment are promising and merit a randomized clinical trial. KEY LEARNING POINTS: Abutment teeth with vital pulps may develop pulp necrosis and apical periodontitis in 10% of cases. Endodontic access preparation through an artificial crown may weaken its retention and jeopardize the longevity of a bridgework. Retrograde root canal treatment is often feasible in maxillary teeth. Results from this preliminary study suggest that treatment outcome for retrograde and orthograde root canal treatment is similar.

The effect of educational intervention on the adoption of nickel-titanium rotary instrumentation in a Public Dental Service.

AIM: To study the influence of two educational programmes on the adoption of nickel-titanium rotary instrumentation (NTRI) amongst general dental practitioners in a short-term as well as a long-term perspective. METHODOLOGY: All dentists employed in the Gothenburg Dental service (n = 148) were enrolled in the study. The clinics in the organization were randomly assigned to one of two educational programmes. In the first programme a 4-h lecture on root canal instrumentation was given. In the second programme the lecture course was supplemented by a 6-h hands-on training session. The short-term effect was measured by a questionnaire distributed 6 months after completed education. The long-term effect was evaluated 4 years later. RESULTS: The overall utilization rate of NTRI increased from 4% to 73%. However, lectures in combination with hands-on training resulted in a better short-term acceptance rate (94%) than if teaching was given only in lecture-format (53%) (P = 0.000). As a consequence, all staff were offered hands-on training. The long-term adoption rate was 88%. Reasons for accepting the new technology usually were found within the 'relative advantage' category. Common reasons for dentists not to adopt NTRI were that they could not get started or that they found no advantage over the old technology. CONCLUSIONS: The short-term adoption of a new technology might be influenced by the design of an introductory educational programme. For clinical procedures, such as root canal instrumentation, the inclusion of hands-on training sessions seems to be important to reach a high acceptance rate.

Improved quality of root fillings provided by general dental practitioners educated in nickel-titanium rotary instrumentation.

AIM: To test the hypothesis that an increased utilization of nickel-titanium rotary instrumentation (NTRI) by general dental practitioners will lead to an increased frequency of good quality root fillings. A second aim was to determine whether the educational format would exert influence on the quality. METHODOLOGY: Dentists were assigned at random to three intervention groups: a 4-h lecture (L-group, n = 40); a 4-h lecture plus a full day hands-on course (LH-group, n = 40); or a control group receiving no instruction (n = 68). The control group received education later on in the study. Radiographs of two root filled molar teeth per dentist were selected at random before the start of the education program and after a 6-month clinical learning period. Using length, seal and shape of root-fillings a 5-level variable was created. RESULTS: The rate of good quality root fillings increased after the introduction of NTRI. Calculated over all types of roots the frequency of excellent (score 1) root fillings increased from 31% to 51% (P = 0.006) in the L-group and from 27% to 47% (P = 0.016) in the LH-group. The frequency of low quality root-fillings (score 5) dropped in the L-group from 22% to 16% (P = 0.29) and in the LH-group from 13% to 9% (P = 0.48). No statistically significant difference was seen among the controls. CONCLUSIONS: When NTRI technology replaced manual stainless steel techniques the rate of good quality root fillings increased. A significant drop in the rate of low quality root fillings was not found.

Root canal treatment in Denmark is most often carried out in carious vital molar teeth and retreatments are rare.

AIM: To study the reasons given by a representative sample of Danish general dental practitioners (GDPs) for undertaking root canal treatment and, to investigate their confidence in performing root canal treatment on molar teeth. METHODOLOGY: A questionnaire was sent to 600 Danish GDPs randomly selected from the roster of the Danish Dental Association. They were asked to recall various factors about their experience of the last root filling they completed, including the reason for treatment and the pulp diagnosis. Self-assessments on 100-mm visual analogue scales (VAS) were reported concerning the confidence in performing root canal treatment of a molar. End-point definitions were 'very easy' (0) and 'very difficult' (100), respectively. Time reports of molar treatments were given in categorized groups. RESULTS: The most frequent reason for performing root canal treatment was caries within the tooth involved (55%). The majority of treatments involved teeth with vital pulps (54%). Retreatments were carried out in 2% of the cases. The confidence in performing root canal treatment varied but was relatively high, expressed as VAS-values below 50. The creation of an aseptic working field was regarded as the most difficult procedure followed by root canal preparation. Fifty-six percent of the responders stated a time frame of 46-75 min to complete root filling in a molar tooth. CONCLUSIONS: Root canal treatment in Denmark was reported to be undertaken most often because of caries. Treatment was typically performed in molar teeth with vital pulp. Even though apical periodontitis was frequently noted in root filled teeth, retreatments were rare. From a subjective perspective root canal treatment was not considered to be very difficult and was carried out relatively rapidly.

A temporary filling material may cause cusp deflection, infractions and fractures in endodontically treated teeth.

AIM: To test the hypothesis that Coltosol F might cause infractions and cusp fracture in root-filled teeth because of material expansion. METHODOLOGY: Thirty-two extracted human molar teeth were root filled and prepared with mesial-occlusal-distal (MOD) cavities with or without undercuts. The specimens were filled proximally with glass-ionomer cement and then occlusally with either Coltosol F or zinc oxide eugenol (ZOE). The tooth specimens were kept in water at 37 degrees C for a period of 20 days, and every second day the intercusp distance (ICD) of each specimen was measured in a travelling microscope, and the number of infraction lines as well as fractures were noted. RESULTS: The number of infraction lines increased in teeth filled with Coltosol F. Between day 8 and 16, seven of 16 teeth filled with Coltosol F showed fracture and exhibited a mean increase in ICD of 316 +/- 156 microm. Teeth filled with ZOE did not show an increase in number of infraction lines or in ICD, and none showed fracture. CONCLUSIONS: The hygroscopic expansion of Coltosol F in a cavity may lead to cusp deflection, infraction development and fracture. Masticatory forces will in vivo aggravate this unfavourable condition. The material is not recommended for temporary filling in root-filled teeth except for a few days.

The adoption of new endodontic technology amongst Danish general dental practitioners.

AIM: To assess the adoption of new endodontic technology in a population of Danish practitioners. METHODOLOGY: Members of the Copenhagen Dental Association (n = 1156) were approached with a questionnaire concerning the frequency of various endodontic procedures. Three options were available: often, occasionally and never. Responses were anonymous. The statistical analyses were performed as studies of association in two- or three-way contingency tables, and with Goodman-Kruskal's gamma-coefficient as the basic tool chosen. RESULTS: Only data from general practitioners (GPs) in private practice were analysed (n = 956). The response rate was 72%. NiTi hand instruments were often used to negotiate canals by 18%, whilst 10% often used NiTi rotary systems. Electronic apex locators were often employed by 15%. Nineteen per cent reported that warm gutta-percha was often used. A majority (53%) often spend two sessions to instrument a molar, and 20% often needed three or more sessions to finish the shaping phase. To complete a treatment of a nonvital case most practitioners reported to use at least three appointments. Only 4% frequently applied rubber dam. CONCLUSIONS: The adoption of new endodontic technology is at an early stage amongst Danish GPs. A new revised remuneration system might influence the rate of adoption, allowing the practitioners to act more rationally and produce a higher frequency of good-quality root fillings. Progress towards high quality endodontics might be hindered by the nonuse of rubber dam.

The annual frequency of root fillings, tooth extractions and pulp-related procedures in Danish adults during 1977-2003.

AIM: To investigate a hypothesized long-time decrease of endodontic treatment in a population with low caries prevalence. METHODOLOGY: A Danish nationwide database including almost all dental diagnostic, prophylactic and therapeutic procedures performed in Danish adults was available. Data on the annual frequencies of root fillings, extractions, pulpotomies, direct pulp cappings and stepwise excavations between 1977 and 2003 were analysed. Data on pulpal and periapical diagnoses were not available and on patients age and gender only from 1996. RESULTS: Between 1977 and 2003 the annual number of root filled canals increased from 268,223 to 364,867 (36%). The annual number of root filled teeth increased from 160,119 to 191,803 (20%). During the period, the annually registered patients increased by 16%. Calculated per 1000 patients, the number of root fillings showed a statistically significant increase of 17%. In root filled teeth the canal/tooth ratio increased from 1.67 to 1.96. Root fillings were frequently recorded in all age groups with the bulk of treatments performed on patients between 40 and 60 years of age. At a total population level, the rate of root fillings decreased among younger individuals and increased among older. The annual number of tooth extractions was more than halved from 656,624 in 1977 to 346,490 in 2003. Pulpotomies decreased markedly over the period and less than 10 treatments per 1000 patients were noted for pulp capping as well as stepwise excavation procedures. CONCLUSIONS: The present study failed to show a long-time decrease of endodontic treatment in a population with low caries prevalence. On the contrary, an increase of root filled canals was observed between 1977 and 2003, which was probably due to a reduction of the tooth extraction rate and an increased treatment of multi-rooted teeth.

Microbiological evaluation of one- and two-visit endodontic treatment of teeth with apical periodontitis: a randomized, clinical trial.

The antimicrobial efficacy of endodontic procedures performed in one-visit (including a 10-min intraappointment dressing with 5% iodine-potassium-iodide) was compared with a two-visit procedure (including an interappointment dressing with calcium-hydroxide paste). Teeth with apical periodontitis (n = 96) were randomly assigned to either group. Root canal sampling and culturing were performed before and immediately after instrumentation, and after medication. Initial sampling demonstrated the presence of microorganisms in 98% of the teeth. Postinstrumentation sampling showed reduction of cultivable microbiota. Antibacterial dressing further reduced the number of teeth with surviving microbes. In the postmedication samples, residual microorganisms were recovered in 29% of the one-visit teeth and in 36% of the two-visit treated teeth. No statistically significant differences between the groups were discerned. It was concluded that from a microbiological point of view, treatment of teeth with apical periodontitis performed in two appointments was not more effective than the investigated one-visit procedure.

The perceived benefit of endodontic retreatment.

AIM: There is substantial variation amongst dentists in the management of symptom-free periapical lesions in root-filled teeth. It has been suggested that this variation can be understood as clinicians' choice of different cut-off points on a continuous periapical health scale (the 'Praxis Concept (PC) theory'). Based on this suggestion, an individual's inclination to propose retreatment can be expressed in the Retreatment Preference Score (RPS). In the present study it was hypothesized that: (i) the PC theory is valid amongst experienced endodontists; and that (ii) interindividual variation in RPS can be explained by a corresponding variation in the perceived benefit of endodontic retreatment. METHODOLOGY: The RPS was determined for 16 experienced Swedish endodontists. The retreatment benefit (RTB) was defined as the gain in utility when a root-filled tooth with a persistent periapical lesion ('health state B') moved to a state where the lesion had healed ('health state A'). For each individual the utility values of the two health states were measured by means of the standard gamble technique. RESULTS: The RPS and RTB were found to be subjected to substantial inter- and intrarater variation. The decision makers acted in accordance with the PC theory. No significant correlation between RPS and RTB was detected. CONCLUSIONS: Findings suggest that the PC theory is valid amongst endodontic experts. The study did not support the notion that the more potential utility that could be produced, the more the individual dentist should tend to perform retreatment. However, alternative consequentialist strategies focusing low risk taking may be involved.

A protocol for polymerase chain reaction detection of Enterococcus faecalis and Enterococcus faecium from the root canal.

AIM: The present study was set up to develop a protocol for detection of Enterococcus faecalis and Enterococcus faecium from the root canal. METHODOLOGY: A collection of type strains and clinical isolates ol E. faecalis and faecium was used. Specific polymerase chain reaction (PCR) primers targeted against the 16S/23S rDNA intergenic region were used and PCR reactions were set up. PCR products were run on TBE-agarose gel and analysed. The sensitivity of the PCR systems was studied using serial dilutions of (i) bacterial DNA and (ii) bacterial cells from E. faecalis. The specificity of the identification was tested against closely related species. RESULTS: All strains of E. faecalis and E. faecium produced identical amplicon profiles composed of two major bands corresponding to sizes of 320 and 420 bp. When amplifying DNA of higher purity, a third band of 600 bp became evident as well. Closely related species demonstrated single bands of various sizes and were easily distinguished from enterococci. The detection level of DNA from serial dilutions of DNA was 10(-13) g. The DNA extraction protocol from bacterial cell suspensions resulted in a detection level of 10 bacterial cells per sample. CONCLUSIONS The present study demonstrated a good potential for using PCR technology in the detection of F. faecalis and E. faecium from root canal samples. With a high specificity the methodology was able to detect 10 cells of E. faecalis.

Identification and antimicrobial susceptibility of enterococci isolated from the root canal.

Enterococci are occurring in opportunistic infections involving the oral cavity. This study has identified enterococcal species in 29 endodontic infections undergoing treatment with Ca (OH)2 dressings. The in vitro antimicrobial susceptibility of 29 isolated enterococcal strains was determined. Enterococcus faecalis was speciated for 26 isolates and Enterococcus faecium for three isolates. In vitro antimicrobial susceptibility testing revealed enterococcal isolates resistant to benzylpenicillin, ampicillin, clindamycin, metronidazole and tetracycline but sensitive to erythromycin and vancomycin. Due to low sensitivity to antimicrobial agents, enterococci may be selected in root canals undergoing standard endodontic treatment and significantly contribute to endodontic treatment failures.

Postoperative discomfort associated with surgical and nonsurgical endodontic retreatment.

Endodontic retreatment decision-making must include an appraisal of the costs of the different strategies proposed. In addition to direct costs, postoperative discomfort may have other consequences in terms of time off work, unscheduled visits and suffering. To establish a foundation for the appraisal of such indirect and intangible costs the present study was set up in which patients' assessments of pain and swelling after surgical and nonsurgical retreatment procedures were recorded. Ninety-two patients with 95 root-filled incisors and canine teeth exhibiting apical periodontitis were included in the study. The mode of retreatment was randomly assigned. Each day during the first post-treatment week patients assessed their degree of swelling and pain on horizontal 100-mm visual analog scales (VAS). The scales ranged from "no swelling" to "very severe swelling" and "no pain" to "intolerable pain", respectively. Consumption of self-prescribed analgesics and time off work were also recorded. Significantly more patients reported discomfort after surgical retreatment than after nonsurgical procedures. High pain scores were most frequent on the operative day while swelling reached its maximum on the first postoperative day followed by progressive decrease both in frequency and magnitude. Postoperative symptoms associated with nonsurgical retreatment were less frequent but reached high VAS values in single cases. Analgesics were significantly more often consumed after periapical surgery. Patients reported absence from work mainly due to swelling and discoloration of the skin. This was found to occur only after surgical retreatment. Conclusively, surgical retreatment resulted in more discomfort and tended to bring about greater indirect costs than nonsurgical retreatment.

Results of endodontic retreatment: a randomized clinical study comparing surgical and nonsurgical procedures.

Information of "success" rates after surgical or nonsurgical endodontic retreatment is abundant but inconclusive. Reported healing frequencies vary between 45% and 90%. The present study was designed to find any systematic difference between the methods. Nonsurgical and surgical retreatment was randomly assigned to 95 endodontically "failed" cases. The outcome of the procedures was clinically and radiographically recorded, and followed for 4 years. At the 12-month recall, a statistically significant (p < 0.05) higher healing rate was observed for cases surgically retreated. At the final 48-month examination, no such difference was found. These findings may be explained by (a) slower healing dynamics in the nonsurgical group and (b) the event of late "failures" in the surgical group. Within the latter category, four cases classified as healed after 1 yr failed at the final follow-up. Conclusively, this study failed to show any systematic difference in the outcome of surgical and nonsurgical endodontic retreatment. Surgical retreatment seems to result in more rapid periapical bone fill, but also may imply a higher risk of "late failures." From a scientific point of view, the length of the follow-up period is very important and may strongly influence the conclusions made.

The antimicrobial effect of calcium hydroxide in root canals pretreated with 5% iodine potassium iodide.

Calcium hydroxide (CH) is often used as a routine interappointment dressing during the endodontic treatment of teeth with apical periodontitis. However, it fails to consistently produce sterile root canals. The present study was set up to find out whether an antimicrobial strategy including the use of CH could be made more effective if: 1) canals were pretreated with 5% iodine potassium iodide (IPI), and 2) the dressing period was extended up to 2 months. Fifty human teeth, with radiographically verified apical periodontitis, were microbiologically sampled. After chemomechanical preparation the canals were pretreated with IPI for 3-7 days. Teeth where microorganisms persisted were then treated with CH for 2 months. Following instrumentation and dressing with IPI, 43 bacterial strains were recovered in 22 of the teeth. Samples obtained after the CH dressing period disclosed growth of 13 facultative and two strict anaerobic strains in 10 teeth. Enterococcus faecalis was identified in two specimens. In conclusion, the present study gave no evidence for an increased antimicrobial effect of CH if it was left for longer periods in the root canal. Although pretreatment with IPI from a quantitative point of view did not seem to add antimicrobial power, it might reduce the frequency of persisting strains of E. faecalis.

The diagnostic accuracy of microbiologic root canal sampling and the influence of antimicrobial dressings.

The routine approach to endodontic treatment of teeth with apical periodontitis often involves an interappointment dressing with calcium hydroxide. However, investigations have demonstrated a negative influence of calcium hydroxide on the accuracy of microbiological root canal sampling (MRS). The aim of the present study was to investigate whether the use of a fluid dressing like 5% iodine potassium iodide (IPI) would increase the accuracy of MRS. Following instrumentation of 50 teeth with radiographically verified apical periodontitis the root canals received IPI as an intracanal dressing. One week after closure canals were sampled, "test sample" (TS), and then left filled with sampling fluid and temporarily scaled. Seven days later a "gold standard" (GS) sample was obtained. Bacteria were recovered in 22 teeth (44%) in TS as well as in GS. Fifteen teeth (30%) were positive for growth in both samples. Using the detection level "very sparse growth" of microbes the sensitivity and specificity of MRS reached 68% and 75%, respectively. In an earlier study, following the same experimental protocol, but with calcium hydroxide as intracanal dressing, the corresponding values were 33% and 81%. In 25% of these cases bacteria persisted in the canals. As compared to calcium hydroxide, the use of IPI resulted in improved test accuracy, but loss of antibacterial capacity. Conclusively, intracanal dressings seem to vary in their influence on the microbiologic test performance as well as in their antibacterial efficacy. In a clinical situation the choice of interappointment dressing should include consideration of these potentially conflicting properties.

Microbiological status of root-filled teeth with apical periodontitis.

The present study examined the microbiological status of 100 root-filled teeth with radiographically verified apical periodontitis--the pathology (P) group--and of 20 teeth without signs of periapical pathosis--the technical (T) group. In the P group 117 strains of bacteria were recovered in 68 teeth. In most of the cases examined one or two strains were found. Facultative anaerobic species predominated among these isolates (69% of identified strains). Growth was classified as 'sparse' or 'very sparse' in 53%, and as 'heavy' or 'very heavy' in 42%. Enterococci were the most frequently isolated genera, showing 'heavy' or 'very heavy' growth in 25 out of 32 cases (78%). In 11 teeth of the T group no bacteria were recovered, whilst the remaining nine yielded 13 microbial strains. Eight of these grew 'very sparsely'. It is concluded that the microflora of the obturated canal differs from that found normally in the untreated necrotic dental pulp, quantitatively as well as qualitatively. Nonsurgical retreatment strategies should be reconsidered.