Indications for root canal treatment in a Swedish county dental service: patient- and tooth-specific characteristics.

AIM: To study patient- and tooth-specific characteristics of teeth indicated for root canal treatment, in the public dental service of the county of Västra Götaland, Sweden. METHODOLOGY: During a designated 8-week period, general dental practitioners working at 20 different public dental clinics consecutively registered indications for undertaking root canal treatment. The patients' subjective level of pain was also registered (visual analogue scale) at the very first appointment. The following information was retrieved from computerized dental records and radiographs: gender, age, number of remaining teeth, tooth group, previous restoration, number of restored surfaces, dental caries and tooth substance loss. Gender and age were compared using both descriptive and analytical statistics. RESULTS: The material comprised 243 teeth in 243 patients: 128 (52.7%) women and 115 (47.3%) men, mean age 48.3 years. Molar teeth predominated (47.7%). Most of the teeth (83.5%) had previously been restored and exhibited significant loss of tooth substance, more than a third of the crown (71.3%). Dental caries was present in 127 teeth (62.9%). Dental trauma was implicated in only seven cases (2.9%). Initial treatment was frequently undertaken at an emergency visit, for relief of symptoms (64.9%). The most commonly registered indication was pulpal necrosis with apical periodontitis (38.1%), followed by pulpitis (37.7%). Retreatment of a root filled tooth was reported in 18 teeth (7.4%). CONCLUSIONS: In the general Public Dental Service of Sweden, root canal treatment is most frequently undertaken in molars. The primary indication is relief of symptoms. Retreatment of root filled teeth is uncommon.

Deep carious lesions and other consequences of caries among 18-year-olds at Public Dental Health Service in Northern Norway: A cross-sectional age cohort study.

OBJECTIVES: To document deep carious lesions and other consequences of caries (DCL-CC) in molars of 18-year olds leaving the free-of-charge Public Dental Health Service (PDHS). To explore the association between background factors and DCL-CC. MATERIALS AND METHODS: The final study sample (n=1876) comprised 95% of individuals born in 1993 and registered in the PDHS in Troms County, Northern Norway. The most recent digital bitewing radiographs of each subject were examined for DCL-CC (deep untreated carious lesions, deep restorations, root canal obturations or extractions due to caries). Inter- and intra-observer kappa scores were 0.62 and 0.87, respectively. Information on background factors (gender, clinic location, history of medical problems, bitewing examination interval, DMFT score and planned recalls) were retrieved from dental records. RESULTS: About one-quarter of subjects (488) had at least one molar with DCL-CC. There were 848 molars in total with DCL-CC; the majority were deep restorations (70%), but 4% were deep untreated carious lesions. More than a quarter of DCL-CC were either root canal obturations (14%) or extractions (12%). Multivariable logistic regression analyses showed that a 1-unit increase in DMFT score was associated with deep untreated carious lesions and extractions due to caries. There was no association between urban/rural clinic location, which indicated socio-economic status, and either DMFT score or DCL-CC. CONCLUSIONS: Despite the existence of a free-of-charge dental service, more than one-quarter of the subjects in the present study had at least one molar with DCL-CC.

Pulp exposures in adults--choice of treatment among Swedish dentists.

This study comprises a survey of Swedish dentists'treatment preferences in cases of carious exposure of the dental pulp in adults.The survey was conducted as part of a comprehensive report on methods of diagnosis and treatment in endodontics, published in 2010 by the Swedish Council on Health Technology Assessment. A questionnaire was mailed to a random subsample of 2012 dental offices where one dentist at each office was requested to answer all questions. Each questionnaire contained one of three sets of questions about endodontic practice routines.Thus around one-third of the subsample received case-specific questions about treating carious exposure. Only general practitioners aged below 70 years were included.The final study sample comprised 412 participants.The dentists were presented with two case scenarios. In Case 1 a 22-year old patient had a deep carious lesion in tooth 36 and in Case 2 a 50-year old patient had a deep carious lesion in tooth 14.The participants were asked to nominate their treatment of choice: pulp capping, partial pulpotomy or pulpectomy. For Case 1, 17 per cent of the respondents selected pulpectomy; the corresponding rate for Case 2 was 47 per cent. Female gender and age group 25-49 years were predictive of selection of less invasive treatment options. However, according to recent guidelines (2011) from the National Board of Health and Wellfare, Swedish dentists are recommended to elect pulpectomy prior to pulp capping/partial pulpotomy when confronted with a tooth having a cariously exposed pulp in adults.

A survey of endodontic practices among dentists in Nigeria.

AIM: To investigate the pattern of routine endodontic practices among Nigerian dentists. MATERIALS AND METHODS: This study was a questionnaire-based survey of samples of dentists in the Nigerian cities of Enugu and Benin. The self-administered questionnaire contained 25 close-ended questions with multiple choice options. The data collected included demographic details of respondents, root canal preparation techniques, irrigants and intracanal medicaments used, the number of appointments, method of working length determination, root filling techniques, cements used, and the scope of treatment performed. RESULTS: Most respondents used sodium hypochlorite as the irrigant, the step back technique for canal preparation, and lateral condensation with a zinc oxide-eugenol-based sealer for obturation. Most respondents did root canal treatment on all types of teeth and used radiographs to determine the working length 70% of the time. Most respondents followed up their patients for less than 12 months and most treated teeth with periapical areas larger than 10 mm by root canal therapy combined with apical surgery. CONCLUSION: Most Nigerian dentists use step back technique for canal preparation and lateral condensation for obturation. CLINICAL SIGNIFICANCE: Endodontic practice by Nigerian dentists differs from some established practice quality guidelines in many other countries, particularly in nonperfusion of modern techniques into practice, popularity of antibiotic use for endodontic emergencies and a high rate of perforations.

An investigation of current endodontic practice in Turkey.

OBJECTIVES: The aim of this study was to gather information about the quality and quantity of root canal treatments carried out by general dental practitioners in Turkey. METHODS: Questionnaires were given to 1400 dentists who attended the 16th National Congress organized by the Turkish Dental Association. The participants were asked to answer 34 multiple-choice questions. The questions were subdivided into 3 main topics; general information; general approach to endodontic treatment; and cleaning, shaping, and obturation of root canals. The statistical analysis was carried out by an χ²-test to compare the means at a significance level of P < 0.05. RESULTS: The response rate for this study was 43%. There was a wide variation in the number of root canal treatments completed per month. Nearly 92% of practitioners stated that they never used rubber dam. The most commonly used working length determination technique was radiographic evaluation (P < 0.05). Sodium hypochlorite was the irrigant of choice with varying concentrations and AH Plus was the sealer of choice (P < 0.05). Resin composite was the most frequently used material for final restorations. CONCLUSIONS: Endodontic procedures in general practice in Turkey have differences from widely acknowledged quality guidelines. Despite the introduction of new instruments and techniques, most of the general practitioners chose conventional methods.

Assessment of the accuracy of two gutta-percha gauges used to alter gutta-percha tip diameter.

This study sought to compare the accuracy of two gauges used to alter gutta-percha (GP) cone tips. Randomly selected size 20 cones (with tapers of 0.02, 0.06, 0.10, or 0.12) were trimmed to size 50 (N= 10/taper/gauge) for an overall sample of 80 cones. Accuracy of the altered cone tips was determined by calculating the difference (in %) between the altered tip diameter and the expected tip diameter (0.50 mm). A two-factor ANOVA revealed significant differences (p < or = 0.05) in altered tip accuracy as a result of GP gauge and cone taper. The results suggest that the SybronEndo gauge performs accurately regardless of the cone taper, while the Maillefer gauge was accurate only when used to alter cones with a 0.02 taper.

Treatment outcome in endodontics: the Toronto study--phases 3 and 4: orthograde retreatment.

Outcome 4-6 years after retreatment was assessed for Phases 3 and 4 of the Toronto Study. Of 477 teeth retreated, 333 were lost to follow-up, 18 were extracted, and 126 (41% recall, excluding 124 discontinuers) were examined for outcome of healed (periapical index score, < or = 2; no signs or symptoms) or diseased. When pooled with Phases 1 and 2, 187 of 229 teeth (82%) were healed. Logistic regression identified significant (P < or = .05) preoperative outcome predictors: root filling quality (odds ratio [OR], 4.18; confidence interval [CI], 1.72-10.12; healed: inadequate, 88%; adequate, 66%), perforation (OR, 4.01; CI, 1.28-12.62; healed: absent, 87%; present, 56%), and radiolucency (OR, 3.33; CI, 1.19-9.36; healed: absent, 93%; present, 80%). In teeth with radiolucency, outcome predictors were number of treatment sessions (OR, 12.08; CI, 1.84-infinity; healed: one, 100%; > or = 2, 77%) and previous root filling quality (OR, 7.68; CI, 2.36-26.89; healed: inadequate, 86%; adequate, 50%). Outcome was better in teeth with inadequate previous root filling, without perforation and radiolucency. Suggested significance of number of treatment sessions in teeth with radiolucency requires validation from randomized controlled trials.

Technical quality of root fillings and periapical status in root filled teeth in Jönköping, Sweden.

AIM: To study changes in technical quality of root fillings and periapical status in root filled teeth in random samples of 20 to 70 year-olds between 1973 and 2003. METHODOLOGY: Data from dentate subjects aged 20-70 years from examinations conducted in 1973 (n = 498), 1983 (n = 530), 1993 (n = 547) and 2003 (n = 491) were used for the analysis. Length of root fillings were measured on radiographs to the nearest 0.1 mm. Adequate seal was defined as a root filling without lateral and/or apical voids. Periapical status was assessed according to the periapical index. All observations were made by one calibrated observer registered from full mouth radiographic examinations. Teeth with root fillings ending within the canal without lateral or apical voids were considered adequate. The association between root filling quality and periapical status was analysed by means of the Chi-squared test and a multilevel logistic regression analysis. RESULTS: Adequately root filled teeth had a significantly lower frequency of apical periodontitis than inadequately root filled teeth (11.8% vs. 22.8%). The frequency of technically adequate root fillings increased statistically significant from 1973 (23.7%) to 2003 (36.4%) without a concomitant improvement of the periapical status in root filled teeth over time (24.5% vs. 24.6%). CONCLUSIONS: This study reports on an improving technical quality of root fillings over time, without a concomitant improvement of the periapical status in root filled teeth. A larger proportion of treated molars over time may be of importance for the result.

[Prevalence of fixed prosthesis-related periodontitis in Senegal]. / Prévalence de la prothèse fixèe et des parodontites apicales associées au Sénégal.

The purpose of this study was to determine radiographically the prevalence of periapical periodontitis in teeth restored with crown in a Senegalese population. Full mouth periapical radiographs were obtained from 208 consecutive adult patients (6234 teeth) presenting as new patients to the Dental Service of the University. The presence of crown restorations, the periapical status and technical quality of root fillings associated were evaluated. 7.69% (n = 16) of patients had at least one tooth that was crowned. The total number of crowns assessed was 0.95% (n = 59). The molars were the teeth most crowned 40.67% (n = 24) followed by anterior teeth 30.50% (n = 18) and premolars 28.81% (n = 17). All the crowned teeth had previous root canal treatment of which only 16.94% (n = 10) were acceptable. 53 % (n = 32) of the teeth had apical periodontitis (PAI > 2). Unacceptable root fillings were associated with a higher prevalence of periapical disease (p < 0.05). Crown with a post extending more than 4 millimetres from the apex were associated with more periapical lesions 64.28% (p < 0.05). The results indicate a low prevalence of crowned teeth, an absence of vital preparation, a high prevalence of radiographic periapical disease and unacceptable root fillings associated.

Evaluación radiográfica de 5000 tratamientos endodónticos realizados en premolares y molares mandibulares y maxilares en una población en Argentina / Radiographic evaluation of 5000 endodontic treatments performed on mandibular and maxillary premolars and molars in a population in Argentina

Objetivo: Evaluar radiográficamente tratamientos en- dodónticos del sector posterior de la cavidad bucal y com- parar la frecuencia de aceptabilidad en cada pieza dentaria involucrada. Materiales y métodos: Se evaluaron 5000 radiogra- fías de archivo de tratamientos endodónticos realizados apro- ximadamente entre 2005 y 2019 en premolares y molares mandibulares y maxilares en Argentina. Se consideraron tratamientos correctos e incorrectos de acuerdo con: 1) con- formación de la preparación quirúrgica; 2) límite apical de la obturación; 3) homogeneidad de la obturación. Se obtuvo la fre- cuencia absoluta y relativa de correctos e incorrectos. El aná- lisis entre frecuencias y pieza dentaria se realizó con la prueba de chi cuadrado y el cálculo del coeficiente V de Cramer. Para la comparación entre grupos de piezas dentarias se utilizó la partición del valor de chi cuadrado obtenido en los corres- pondientes grados de libertad. Nivel de significación P <0.05. Resultados: La partición del valor de chi cuadrado no mostró diferencias significativas entre primeros y segundos premolares mandibulares. Las otras comparaciones exhibie- ron diferencias significativas. Conclusiones: Un alto porcentaje de los tratamientos endodónticos de la población estudiada tiene por lo menos una condición que permite categorizarlos como incorrectos según el criterio establecido en este trabajo. Este porcentaje es más preponderante en anatomías complejas (AU)

Aim: To evaluate radiographically endodontic treat- ments performed in the posterior area of the oral cavity and compare the frequency of acceptability in each tooth involved. Materials and methods: 5,000 archival radiographs of endodontic treatments performed between 2005 and 2019 on mandibular and maxillary premolars and molars in Argentina were evaluated. The percentages of correct and incorrect treatments were considered according to 1) shaping of the preparation; 2) apical limit of the obturation; 3) homogeneity of the obturation. The absolute and relative frequencies of correct and incorrect treatments were calcu- lated. The association between these frequencies and tooth type was analyzed using the chi-square test and Cramer's V coefficient. For the comparison between groups of teeth, the partition of the chi-square value obtained in the corre- sponding degrees of freedom was used. Level of significance was P <0.05. Results: The partition of the chi-square value did not show a significant difference between the first and second lower premolars. The differences were significant in the other comparisons. Conclusions: A high percentage of the endodontic treat- ments in the study population have at least one condition war- ranting their classification as incorrect according to the crite- ria established in this study. This percentage is more prevalent in complex anatomies (AU)

Radiologic assessment of quality of root canal fillings and periapical status in an Austrian subpopulation - An observational study.

BACKGROUND/OBJECTIVE: Progress in endodontic techniques and methodological advances have altered root canal therapy over the last decades. These techniques and methods need periodical documentation. This observational study determined the current prevalence of endodontic treatments, and investigated the relationship of various factors with the periapical status in a Lower Austrian subpopulation. METHODOLOGY: One thousand orthopantomograms of first-time university adult patients radiographed at an outpatient clinic were evaluated. For each tooth, the presence of periradicular pathosis and/or endodontic treatment was recorded, as was the quality of (post-)endodontic treatment (homogeneity and length of root canal fillings; preparation failures; posts/screws; apicoectomies; coronal restorations). Two evaluators, blinded to each other, scored all teeth. In cases of disagreement, they joined for a consensus score. RESULTS: In all, 22,586 teeth were counted. Of these, 2,907 teeth (12.9%) had periapical pathosis, while 2,504 teeth had undergone root canal treatment. Of the endodontically treated teeth, 52% showed no radiographic signs of apical periodontitis, while 44.9% had overt apical lesions, and 3,1% revealed widened periodontal ligament space. The majority of the root canal fillings was inhomogeneous (70.4%); 75.4% were rated too short, and 3.8% too long. The presence of apical pathosis was significantly correlated (odds ratio (OR) 2.556 [confidence interval (CI) 2.076-3.146]; P<0.0001) with poor root canal fillings (length and homogeneity). Posts or screws positively affected periapical status (OR 1.853 [CI 1.219-2.819]; P = 0.004), but endodontically treated posterior teeth were infrequently restored (posts, 7.5%; screws, 2.7%). Best results were found for teeth with both appropriate endodontic treatment and adequate coronal restoration. CONCLUSION: A high prevalence of periradicular radiolucencies was observed with root canal filled teeth, along with high numbers of unmet treatment needs. Periapical health was associated with adequate root canal obturation and high-grade postendodontic restorations, and quality regarding these latter aspects is considered mandatory to promote periapical health.

A radiographic study of the prevalence of endodontically treated teeth and procedural errors of root canal filling.

The aim of this radiographic investigation was to study procedural errors encounterd in root canal treatment in a Jordanian population as evidenced using periapical radiographs A total of 2380 periapical radiographs including 3178 endodontically treated teeth were assessed in respect of the quality of endodontic treatment. The results indicated that the prevalence of endodontically treated teeth in the maxilla was higher than that in the mandible ( P < 0.001 ), the maxillary central incisors have the highest prevalence of endodontic treatment, and the maxillary second molars have the lowest prevalence of endodontic treatment. In respect of the quality of endodontic treatment, 30.2% of endodontically treated teeth exhibited an ideal length of root canal filling, 23.64% of the evaluated teeth were mummified, 37.45% of the teeth have short root canal fillings, 6.25% were overfilled, 1.35% were with preparations which deviated from the line of the root canal and 1.10% of the evaluated teeth have perforations of the root walls or the floor of the pulp chamber. It is concluded that the Maxillary teeth were found to be endodontically treated more frequently than the mandibular teeth, anterior teeth were found to be endodontically treated more than premolar and molar teeth, maxillary central incisors have the highest prevalence of endodontic treatment whilst the maxillary second molars have the lowest prevalence. The quality of endodontic treatment was disappointing. Therefore, emphasis on continuing education and post graduate courses in endodontics must be a priority in Jordan.

Evaluación del éxito de tratamientos endodónticos realizados por estudiantes de pregrado en una universidad chilena / Evaluation of success rate of root canal treatment performed by undergraduate dental students in a Chilean university

El tratamiento endodóntico tiene como finalidad prevenir o lograr la ausencia de periodontitis apical post-tratamiento, logrando la mantención del diente en la boca de manera funcional. La realización de tratamientos endodónticos de baja complejidad en la formación de pregrado es transversal a todas las universidades chilenas. El objetivo del presente estudio es evaluar la frecuencia de éxito de tratamientos endodónticos realizados por estudiantes de pregrado entre los años 2014-2017 de la Escuela de Odontología, Universidad Austral de Chile (UACh), Valdivia, Chile. Se realizó un estudio observacional descriptivo donde fueron evaluados 74 tratamientos endodónticos en dientes uniradiculares de 63 pacientes seleccionados a través de un muestreo aleatorio simple, que cumplieran con los criterios de selección. Los parámetros usados para la evaluación clínica fueron: ausencia de dolor a la palpación y percusión, ausencia de fístula y diente en función. En la evaluación radiográfica se utilizaron los siguientes parámetros: longitud de obturación en relación al ápice dentario, conicidad, densidad del material obturador y reducción de la lesión periapical. De los tratamientos evaluados se reportó un 78 % de éxito clínico y un 41 % de éxito radiográfico. Finalmente, se concluye que los resultados obtenidos a nivel clínico y radiográfico son similares a los reportados en la literatura.

The objective of endodontic treatment is to prevent or achieve the absence of post-treatment apical periodontitis, thereby maintaining functionality of the tooth in the mouth. In Chilean universities undergraduate programs, training in endodontics is limited to low level complexity cases and is transversal throughout the universities. The objective of this study is to evaluate the frequency of success of endodontic treatments performed by undergraduate students between the years 2014-2017 of the School of Dentistry, Universidad Austral de Chile (UACh), Valdivia, Chile. A descriptive observational study was conducted where 74 endodontic treatments were evaluated in uniradicular teeth of 63 patients, selected through a simple random sampling, that met selection criteria. The criteria used for the clinical evaluation were: absence of pain on palpation and percussion, absence of fistula and function tooth. In the radiographic evaluation the following criteria were used: length of obturation in relation to the dental apex, taper, density of the obturator material and reduction of the periapical lesion. Of the treatments evaluated, 78 % clinical success and 41 % radiographic success were reported. Finally, it is concluded that the results obtained at clinical and radiographic level are similar to those reported in the literature.

Analysis of a referral-based endodontic practice: Part 2. Treatment provided.

Little information exists in the dental literature regarding the range of treatment provided by specialist endodontists. This study was undertaken to analyze the range and incidence of treatment procedures performed on 2000 patients referred to a specialist endodontist in Perth, Western Australia. There were 312 people that did not require endodontic treatment, resulting in 1688 patients having treatment on 2221 teeth. Routine treatment without complications was provided to 313 teeth (14%) while a total of 451 teeth (20.3%) had calcified or blocked canals. Endodontic retreatment was necessary in 815 teeth (36.7%), 210 teeth (9.4%) had posts removed, and 236 (10.6%) had endodontic surgery. Perforations were present in 119 teeth (5.4%) and these were treated either conservatively (81 teeth, 3.6%) or with surgery (38 teeth, 1.7%). Dental trauma was the reason for referral of 258 patients who required treatment on 217 teeth (9.8%). The wide range of treatment procedures required indicates that endodontists must be highly skilled in all aspects of the discipline.

A survey of filling methods, intracanal medications, and instrument breakage.

The present survey was conducted to obtain answers to some basic questions regarding the use of intracanal medications, root canal filling methods, and the intracanal breakage of instruments. A letter was sent to 300 endodontists listed in the 1995-1996 membership roster of the American Association of Endodontists. Eighty-five replies were received. Calcium hydroxide as an intracanal medication was used by 91.7% of the responding endodontists. With regard to the root canal filling technique, 52.9% used the lateral condensation method. When intracanal breakage occurred, 95.3% of the respondents informed the patient. The results of this survey provide useful information for the education of undergraduate dental students.

Effect of masticatory cycles on tooth compression and resultant leakage of amalgam retrofills.

This study was carried out to investigate the effect of changes in tooth structure due to masticatory cycles on amalgam retrofillings performed to different cavity depths. Forty upper maxillary first molars were tested. In the obturated palatal root apical amalgam was inserted to different depths (1.5 and 3 mm). Eight casts were built, each having four sample molars. To block the teeth, the vestibular roots were embedded in resin (palatal root was left free). The eight remaining retrofilled teeth served as controls and were not submitted to occlusal forces. A mechanical device to simulate masticatory cycles subjected the teeth to 500,000 to three million cycles. Leakage was assessed from dye penetration observations. The values of microleakage were analyzed and compared, and strain gauges were used to assess structural modifications to the tooth. The leakage of all retrofilled obturations increased in correlation with the number of masticatory cycles. At three million cycles, root length compression was 0.3 +/- 0.02%. Leakage was significantly less for the deeper cavity preparations at all stages. This in vitro study suggests a significant effect by root compression due to masticatory loads on the leakage of retrofilled amalgam obturations.

A comparison of thermoplastic obturation techniques: adaptation to the canal walls.

The purpose of this study was to directly compare the ability of the three types of Thermafil obturators, the Obtura II thermoplasticized injectable technique, and the lateral condensation technique to obturate a standardized root canal. A split-tooth model was constructed and the root canal was obturated 20 times with each technique. The quality of each obturation was graded according to established criteria of adaptation. Statistical analysis of the results indicated that all the techniques were significantly different from each other (p < 0.0001) except for the plastic and titanium Thermafil groups (p > 0.05), which were similar. Based on the evaluated criteria, the Obtura II injectable technique demonstrated the best adaptation to the prepared root canal. This group was followed in order by the plastic and titanium Thermafil obturators, the stainless steel Thermafil obturators, and finally by the lateral condensation technique.

Coronal leakage: effects of smear layer, obturation technique, and sealer.

Coronal microleakage may be a major factor in the etiology of treatment failure. This study examined the effect of obturation technique, sealer, and the presence of smear layer on coronal microleakage. Two hundred extracted human teeth were assigned to 20 treatment groups. Groups were examined with the smear layer present or smear layer removed (17% REDTA). Access cavities were exposed to artificial saliva then Pelikan Ink. Teeth were cleared and linear dye penetration measured. When all groups with the smear layer removed were compared with all groups with the smear layer present, significantly less leakage was seen when the smear layer was removed. Ultrafil displayed significantly more leakage than all other groups. Vertical compaction of lateral condensation and Thermafil obturations significantly reduced leakage. AH-26 displayed significantly less leakage than Roth's 811 sealer. These results indicate that removal of the smear layer, the use of AH-26, and vertical compactin have cumulative effects in reducing coronal leakage.

The effect of ultrasonics on sealer distribution and sealing of root canals.

The purpose of this study was to compare the ultrasonic and hand methods of sealer placement using three types of sealers: Sultan "Grossman's formula," AH-26, and CRCS. The effect of these methods on radiographic density, sealer distribution, and on the apical seal of the different sealers was evaluated. The in vitro experiment was carried out using human extracted mandibular incisors and mesio-buccal roots of maxillary first and second molars. Following standardized canal instrumentation, 120 single canal mandibular incisors were randomly assigned to six groups, depending on the type of sealer and method of sealer placement (hand versus ultrasonic). An additional ten teeth were used as controls. In the molar groups 40 canals were randomly assigned to two groups, with the method of sealer placement as the variable. Eight canals were used as controls. Postsealer analyses using radiographic density scores transformed to mm of sealer indicated that ultrasonics was superior to manual placement only for CRCS. Taken together, our investigation suggests that ultrasonics may enhance the placement of some sealers (i.e. CRCS) but not of others (i.e. AH-26 or Sultan). Method of sealer placement had no effect on apical leakage and therefore apparently on apical seal.

Additional studies on the distribution of stresses during vertical compaction of gutta-percha in the root canal.

OBJECTIVE: This study was designed to investigate the effect of certain pathological alterations of the dental structures (diminishing bone support, internal resorption, root perforation, periapical lesion) on stress distribution during root canal filling procedures by the warm vertical compaction technique. DESIGN: The computer stress analyses were done for a maxillary canine tooth model which was based on dimensions recovered from a human cadaveric maxilla scanned by CT. METHODS: The finite element method was used to calculate the stresses generated during root canal filling procedures by warm vertical compaction technique. Patterns of stress distribution associated with various alterations in dental structures were investigated. For this purpose 60 cases were simulated. The hypothetical force of 10 N is taken as a unit representation. For other magnitudes of applied force, the corresponding stresses would be scaled directly because the calculations were made for linear materials. RESULTS AND CONCLUSION: It is found that, when diminishing bone support and internal resorption are concurrently simulated, a marked increase in stress magnitudes occur (maximum von Mises stress 5.37 N/mm2). However, these values still remain much below the most frequently reported tensile strength of dentine (50-100 N/mm2). If dentist's handwork is transformed into equivalent edge tractions on gutta-percha, then stresses in dentine, even when they are corrected for 3-kg applied force, appear to remain below fracture strengths of this material. This result leads us to conclude that when warm vertical compaction technique is skillfully performed and inadvertent undue force is not applied, a premature root fracture in a large rooted maxillary anterior tooth with straight root canal anatomy is not likely to occur, even for the unfavourable conditions simulated in our model. This result, like all results derived from modelling applications, is of course contingent upon agreement between the way in which the clinical operations are performed and the way in which they are mirrored for computer representation. We believe that the approach described here avoids the spurious stresses that have been reported in similar investigations.