Assessment of conformity between clinical (radiological) and histopathological diagnoses of chronic inflammatory periapical lesions treated with apicoectomy. Clinical and histopathological diagnoses of periapical lesions. Research article.

OBJECTIVES: Periapical inflammation is one of the most common pathologies within the jaws, leading to the destruction of periodontal ligaments, bone resorption and the formation of periapical granulomas or radicular cysts. The final diagnosis can be made only on the basis of histopathological examination. The aim of the study was to assess the conformity between clinical and histopathological diagnosis of inflammatory periapical lesions treated with apicoectomy. MATERIALS AND METHODS: The case histories of 52 patients subjected to surgical treatment at the Clinic of Conservative Dentistry with Endodontics between 2008 and 2018 were analyzed. Demographic data (age, gender), clinical (radiological) diagnosis, and data on the presence of sinus tracts and causal tooth were obtained from patients' records. RESULTS: In the light of clinical and radiological examination, 32 (61.5%) periapical granulomas, 18 (34.6%) radicular cysts and 2 (3.9%) periapical scars were diagnosed, whereas the result of histopathological examination revealed granuloma in 34 (65.4%) cases and in 18 (34.6%) - radicular cyst. For clinical diagnosis of granuloma, the result coincided with the result of the histopathological examination in 28 cases, and in the case of cysts in 14. The analysis showed a significant relationship between the clinical and histopathological diagnoses (p <0.05). CONCLUSIONS: The study emphasizes the importance of histopathological assessment for the proper diagnosis of periapical lesions. CLINICAL RELEVANCE: The article emphasizes the high importance of histopathological examination for the correct diagnosis of chronic inflammatory periapical lesions.

Clinician-centered Outcomes Assessment of Retreatment and Endodontic Microsurgery Using Cone-beam Computed Tomographic Volumetric Analysis.

INTRODUCTION: Outcomes assessment of retreatment and endodontic microsurgery (EMS) are traditionally based on clinical findings and radiographs. The purpose of this study was to assess the volumetric change of periapical radiolucencies (PARLs) by cone-beam computed tomographic (CBCT)-based analysis in retreatment and EMS cases. METHODS: For 68 retreatment and 57 EMS cases, preoperative and recall clinical data, periapical (PA) radiographs, and CBCT imaging were retrospectively obtained. Specialized software was used by 2 board-certified endodontists for volumetric analysis of PARLs. For EMS and retreatment, clinical outcomes were determined by combining clinical data with CBCT-generated volumetric analysis (PA radiographs not used). Additionally, comparisons of percent volume reduction for EMS and retreatment were performed. Examiner interpretations of outcomes assessment using PA radiography and CBCT imaging were compared. RESULTS: In teeth with or without a preoperative PARL, EMS resulted in a statistically significant difference in complete healing (49/57 [86.0%]) versus retreatment (28/68 [41.2%], P < .0001). EMS resulted in a statistically significant difference in combined complete healing and reductive healing (54/57 [94.7%]) versus retreatment (56/68 [82.4%], P < .05). Of 46 recalls in which CBCT imaging detected a PARL, PA radiography detected 30 (a 35% false-negative rate). Of the 79 recall studies in which CBCT imaging did not detect a PARL, PA radiography did detect PARL in 13 (a 16.5% false-positive rate). CONCLUSIONS: In this CBCT and clinical data-based outcomes assessment, EMS resulted in a greater mean volumetric reduction and a higher healing rate compared with retreatment. Postoperative CBCT imaging is more sensitive and specific than PA radiography in assessing PARL and has demonstrable usefulness in outcomes assessment.

Peri-implant assessment via cone beam computed tomography and digital periapical radiography: an ex vivo study.

OBJECTIVES: This research evaluated detail registration in peri-implant bone using two different cone beam computer tomography systems and a digital periapical radiograph. METHODS: Three different image acquisition protocols were established for each cone beam computer tomography apparatus, and three clinical situations were simulated in an ex vivo fresh pig mandible: buccal bone defect, peri-implant bone defect, and bone contact. Data were subjected to two analyses: quantitative and qualitative. The quantitative analyses involved a comparison of real specimen measures using a digital caliper in three regions of the preserved buccal bone - A, B and E (control group) - to cone beam computer tomography images obtained with different protocols (kp1, kp2, kp3, ip1, ip2, and ip3). In the qualitative analyses, the ability to register peri-implant details via tomography and digital periapical radiography was verified, as indicated by twelve evaluators. Data were analyzed with ANOVA and Tukey's test (α=0.05). RESULTS: The quantitative assessment showed means statistically equal to those of the control group under the following conditions: buccal bone defect B and E with kp1 and ip1, peri-implant bone defect E with kp2 and kp3, and bone contact A with kp1, kp2, kp3, and ip2. Qualitatively, only bone contacts were significantly different among the assessments, and the p3 results differed from the p1 and p2 results. The other results were statistically equivalent. CONCLUSIONS: The registration of peri-implant details was influenced by the image acquisition protocol, although metal artifacts were produced in all situations. The evaluators preferred the Kodak 9000 3D cone beam computer tomography in most cases. The evaluators identified buccal bone defects better with cone beam computer tomography and identified peri-implant bone defects better with digital periapical radiography.

Peri-implant assessment via cone beam computed tomography and digital periapical radiography: an ex vivo study

OBJECTIVES: This research evaluated detail registration in peri-implant bone using two different cone beam computer tomography systems and a digital periapical radiograph. METHODS: Three different image acquisition protocols were established for each cone beam computer tomography apparatus, and three clinical situations were simulated in an ex vivo fresh pig mandible: buccal bone defect, peri-implant bone defect, and bone contact. Data were subjected to two analyses: quantitative and qualitative. The quantitative analyses involved a comparison of real specimen measures using a digital caliper in three regions of the preserved buccal bone - A, B and E (control group) - to cone beam computer tomography images obtained with different protocols (kp1, kp2, kp3, ip1, ip2, and ip3). In the qualitative analyses, the ability to register peri-implant details via tomography and digital periapical radiography was verified, as indicated by twelve evaluators. Data were analyzed with ANOVA and Tukey's test (α=0.05). RESULTS: The quantitative assessment showed means statistically equal to those of the control group under the following conditions: buccal bone defect B and E with kp1 and ip1, peri-implant bone defect E with kp2 and kp3, and bone contact A with kp1, kp2, kp3, and ip2. Qualitatively, only bone contacts were significantly different among the assessments, and the p3 results differed from the p1 and p2 results. The other results were statistically equivalent. CONCLUSIONS: The registration of peri-implant details was influenced by the image acquisition protocol, although metal artifacts were produced in all situations. The evaluators preferred the Kodak 9000 3D cone beam computer tomography in most cases. The evaluators identified buccal bone defects better with cone beam computer tomography and identified peri-implant bone defects better with digital periapical radiography.

Change in Periapical Lesion and Adjacent Mucosal Thickening Dimensions One Year after Endodontic Treatment: Volumetric Cone-beam Computed Tomography Assessment.

INTRODUCTION: Changes in periapical lesion dimensions along with mucosal thickening after endodontic treatment have not been studied yet. Therefore, the objectives of this study were (1) to obtain linear and volumetric measurements of lesion dimensions in maxillary first molars with periapical pathology and (2) to measure maxillary sinus mucosal thickening in the vicinity of periapical lesions before and 1 year after endodontic treatment by using cone-beam computed tomography (CBCT). METHODS: Twenty-one maxillary first molar teeth of 21 patients (14 female and 7 male) with periapical lesion that had local mucosal thickening in the vicinity of the periapical lesion were endodontically treated. A total of 21 maxillary first molar roots (8 mesiobuccal roots, 6 distobuccal roots, and 7 palatal roots), each one from different patients, was included. Pretreatment and 1-year post-treatment CBCT images of each tooth were obtained by using Kodak CS 9300 3D CBCT unit. Width, height, surface area, and volume measurements of periapical lesions and mucosal thickening of the maxillary sinus mucosa in the vicinity of the periapical lesion were measured before and 1 year after endodontic treatment. General linear model (analysis of variance) was used for the comparisons between measurements, and significance was set at P < .05. Regression analysis was also used to test the correlation between different measurements. RESULTS: We found statistically significant differences between mean pretreatment and mean post-treatment measurements conducted by using CBCT images (width, P = .002; height, P < .001; maximum mucosal thickening, P < .001; medium mucosal thickening, P < .001; minimum mucosal thickening, P < .001; surface area, P = .032; and volume, P = .034). Considering gender, age, and root-type variables, no significant differences were found for all the measurements conducted (P > .05). There were 36%, 41%, 53%, 54%, 53%, 73%, and 75% mean reductions in lesion width, lesion height, maximum sinus mucosal thickness, medium sinus mucosal thickness, minimum sinus mucosal thickness, lesion surface area, and lesion volume, respectively, before and 1 year after endodontic treatment. Regression analysis of pretreatment lesion volume versus percentage of post-treatment lesion volume change revealed a low regression coefficient (R2 = 16.7%, P > .05), showing a weak linear relationship. CONCLUSIONS: CBCT assessment of changes in periapical lesion and mucosal thickening dimensions may reveal useful information regarding endodontic treatment success.

Use of micro-computed tomography for the assessment of periapical lesions in small rodents: a systematic review.

This systematic review aimed to evaluate the literature on the acquisition-, reconstruction- and analysis parameters of micro-computed tomography (micro-CT) for the assessment of periapical lesions in rats and mice, and to illustrate the effect of variation in these parameters. The PubMed database was searched from 2000 to January 2015 (English-language publications) for reports on the use of micro-CT to evaluate periapical lesions in rats and mice. QUADAS criteria were used to rate the quality of the studies. To illustrate the effect of variations in acquisition-, reconstruction-, and analysis parameters on images of periapical lesions, micro-CT examination of two hemi-mandibles of mice, with periapical lesions around the first molar was undertaken. Twenty-one studies were identified, which analysed periapical lesions in rats or mice using micro-CT. According to the QUADAS, no study was classified as high-, seven were classified as moderate-, and 14 as low quality. The effect of variation in parameters was that voxel size may interfere with image sharpness, reconstruction may interfere with image sharpness and contrast, and inadequate plane orientation may alter the size of the periapical lesion. Nonpersonalized ROIs resulted in areas that were not part of the periapical lesion. Changing the limits of the threshold for bone-tissue visualization increased lesion size. There is no defined protocol for acquiring and analysing micro-CT images of periapical lesions in rats and mice. Furthermore, acquisition-, reconstruction- and analysis parameters are not adequately explained, which may compromise the scientific impact of the studies.

Assessment of Correlation between Clinical Parameters and Pulp Canal Pathogens in Endodontic Pathologies: A Microbiological Study.

INTRODUCTION: Success and failure of root canal therapy is largely dependent on the clinician and the patient. Once the tooth is restored into its functional and esthetic place, the root canal therapy is considered to be complete. It is a well-known fact that root canal space acts as a rich reservoir for microorganisms. Past studies show that root canal harbors an array of different microorganisms. Streptococcus mitis and Enterococcus faecalis have been found to be the most prevalent microorganisms isolated from the infected pulp canal space. Hence, we evaluated the association of endodontic signs and symptoms with root canal pathogens. MATERIALS AND METHODS: A total of 120 patients were selected for the study and divided broadly into two groups: Group I containing patients with primary infection and group II containing patients in which retreatment was required. Both groups contained 60 patients each. Clinical parameters recorded for the study are pain, tenderness on percussion, swelling, periapical radiolucency on radiographic analysis, caries, sinus formation, and tooth mobility. After assessment, opening, and initial filing, sterile paper points were inserted into the root canal space for collection of microbiological sample, which was further send to laboratory for cultural analysis. All the results were analyzed by Statistical Package for the Social Sciences (SPSS) software. Student's t-test and Fisher's exact test were used to evaluate the level of significance. RESULTS: While comparing the mean age of the patients in the two groups, no significant association was seen. Statistically significant results were obtained while comparing the association between pain and S. mitis. Positive correlation was seen on comparing the association between tenderness on percussion and E. faecalis. Also, a positive association was seen between periapical radiolucency and S. mitis. CONCLUSION: Strong positive correlation exists between S. mitis and E. faecalis and endodontic signs and symptoms. CLINICAL SIGNIFICANCE: Sound knowledge regarding the association of microbes of root canal and specific endodontic signs and symptoms could help therapeutic management of root canal infections effectively.

Evaluation of New Cone-beam Computed Tomographic Criteria for Radiographic Healing Evaluation after Apical Surgery: Assessment of Repeatability and Reproducibility.

INTRODUCTION: Conventional 2-dimensional radiography uses defined criteria for outcome assessment of apical surgery. However, these radiographic healing criteria are not applicable for 3-dimensional radiography. The present study evaluated the repeatability and reproducibility of new cone-beam computed tomographic (CBCT)-based healing criteria for the judgment of periapical healing 1 year after apical surgery. METHODS: CBCT scans taken 1 year after apical surgery (61 roots of 54 teeth in 54 patients, mean age = 54.4 years) were evaluated by 3 blinded and calibrated observers using 4 different indices. Reformatted buccolingual CBCT sections through the longitudinal axis of the treated roots were analyzed. Radiographic healing was assessed at the resection plane (R index), within the apical area (A index), of the cortical plate (C index), and regarding a combined apical-cortical area (B index). All readings were performed twice to calculate the intraobserver agreement (repeatability). Second-time readings were used for analyzing the interobserver agreement (reproducibility). Various statistical tests (Cohen, kappa, Fisher, and Spearman) were performed to measure the intra- and interobserver concurrence, the variability of score ratios, and the correlation of indices. RESULTS: For all indices, the rates of identical first- and second-time scores were always higher than 80% (intraobserver Cohen κ values ranging from 0.793 to 0.963). The B index (94.0%) showed the highest intraobserver agreement. Regarding interobserver agreement, the highest rate was found for the B index (72.1%). The Fleiss' κ values for R and B indices exhibited substantial agreement (0.626 and 0.717, respectively), whereas the values for A and C indices showed moderate agreement (0.561 and 0.573, respectively). The Spearman correlation coefficients for R, A, C, and B indices all exhibited a moderate to very strong correlation with the highest correlation found between C and B indices (rs = 0.8069). CONCLUSIONS: All indices showed an excellent intraobserver agreement (repeatability). With regard to interobserver agreement (reproducibility), the B index (healing of apical and cortical defects combined) and the R index (healing on the resection plane) showed substantial congruence and thus are to be recommended in future studies when using buccolingual CBCT sections for radiographic outcome assessment of apical surgery.

Radiologic Assessment of Periapical Health: Comparison of 3 Different Index Systems.

INTRODUCTION: The aim of this study was to evaluate observer variations and observer reproducibility in the interpretation of periapical health using the Strindberg system, the periapical index (PAI), and the probability index for radiologic assessment of periapical health. METHODS: Four observers read digital periapical images to evaluate the periapical health of 200 root-filled teeth. Each observer evaluated a tooth twice by using the Strindberg system, twice by using the PAI, and twice by using the probability index. Each observation session was held at 1-month intervals. Three scores were used for the evaluations conducted by using the Strindberg system. Both the PAI and the probability index were considered on 5-point scales and were also dichotomized. SPSS for Windows 15.0 software (SPSS Inc, Chicago, IL) was used for data analysis, and intra- and interobserver agreements were described by using kappa statistics. RESULTS: The average kappa values of intra- and interobserver agreement calculated for the Strindberg system were 0.53 and 0.36, respectively. The corresponding average kappa values were calculated as 0.48 and 0.39 for the PAI and 0.45 and 0.30 for the probability index. The highest mean proportion values of intra- and interobserver agreement were observed for the dichotomization of the PAI (88.9% and 87.0%, respectively) followed by the dichotomization of the probability index (86.8% and 82.9%, respectively). CONCLUSIONS: The Strindberg system has lower intraobserver variation compared with the PAI and the probability index, whereas PAI has lower interobserver variation compared with the Strindberg system and the probability index. The dichotomization of the PAI and the probability index provided higher intra- and interobserver agreement values in the radiologic assessment of periapical health.

Important technical parameters are not presented in reports of intraoral digital radiography in endodontic treatment: recommendations for future studies.

OBJECTIVES: The aims of this study were to review the literature on intraoral digital radiography in endodontic treatment with focus on technical parameters and to propose recommendations for improving the quality of reports in future publications. STUDY DESIGN: Two electronic databases were searched. Titles and abstracts were selected according to preestablished criteria. Data were extracted using a model of image acquisition and interpretation. RESULTS: The literature search yielded 233 titles and abstracts; 61 reports were read in full text. Recent reports presented technical parameters more thoroughly than older reports. Most reported important parameters for the x-ray unit, but for image interpretation only about one-half of the publications cited resolution of the display system and fewer than one-half bit depth of the graphics card. CONCLUSIONS: The methodologic quality of future publications must be improved to permit replication of studies and comparison of results between studies in dental digital radiography. Our recommendations can improve the quality of studies on diagnostic accuracy.

A comparative diagnostic assessment of anterior tooth and bone status using panoramic and periapical radiography.

AIMS: The aim of the present study was to compare diagnostic assessments of anterior tooth and bone status in a randomised cohort of pre-orthodontic patients using panoramic and periapical radiographs. METHOD: Four hundred and forty-four cases with matched periapical and panoramic radiographs were examined by three observers. Two were final-year postgraduate endodontic students and the other, a final-year Honours degree dental student. Multi-rater Kappa values were used to assess the reliability of the observers, with a value of 1 equating to complete agreement. RESULTS: With the exception of endodontic Class 1 and 2 palatal invaginations, reliability exceeded 0.95 for all three observers. An assessment of the graduate endodontic students revealed only a marginal increase in the kappa values. Statistical analysis (p < 0.05) determined that developmental anomalies or tooth/bone pathoses were more reliably detected by observers using periapical radiographs compared with panoramic films. This finding has relevance given the likelihood of anterior dental trauma among young children. CONCLUSION: While there have been considerable improvements in the quality of dental panoramic radiography, the present study indicated that a reliable pre-orthodontic or post-trauma diagnostic assessment should include both panoramic and intra-oral radiographs.

Assessment of the anterior maxilla in orthodontic patients using upper anterior occlusal radiographs and dental panoramic tomography: a comparison.

OBJECTIVE: The aim of this study was to establish if dental panoramic tomographic (DPT) radiographs provide a reliable means of assessing the anterior maxilla in new orthodontic patients. STUDY DESIGN: Two hundred fifty pairs of upper anterior occlusal (UAO) and DPT radiographs were randomly selected from the records of new orthodontic patients. Ten observers each rated 50 pairs of radiographs for specific risk factors as well as for a measure of adequacy. Correlations between the 2 radiograph types and inter/intraobserver reliability were computed using Cohen kappa test. RESULTS: Intraobserver reliability was good for detection of impacted teeth/supernumeraries/periapical pathology (kappa = 0.711-1.0). Reliability was more variable for the specific root morphologies, with blunt and bent roots being reassessed as such most reliably (kappa = 0.259-0.533). There was low interobserver reliability (kappa = 0.327 for UAO and kappa = 0.223 for DPT) for "normal" or "not normal" root morphology. For every variable, however, the interexaminer agreement was higher when using UAO radiographs rather than DPTs. Observers were best able to agree on the diagnosis of eroded/resorbed roots on the UAO (kappa = 0.402) and blunt roots (kappa = 0.303) on the DPT radiographs. With UAO as the gold (reference) standard for grading root morphology, DPT had a sensitivity of 45.6% and a specificity of 71.4% for detecting abnormal root form. Risk factors were more likely to be detected on the UAO radiographs than the DPTs. DPTs had a poor ability to detect abnormal root form. DPTs were more likely to be rated as "inadequate" than UAO radiographs. On 6 occasions, supernumerary teeth that were observed on the UAO were missed on the DPT. CONCLUSION: The DPT is not an accurate means of screening the anterior maxilla prior to orthodontic treatment.

Cone-beam CT diagnostic applications: caries, periodontal bone assessment, and endodontic applications.

Cone-beam CT (CBCT) is useful for many maxillofacial applications, such as implant site imaging and diagnosis and treatment planning for orthodontics and craniofacial surgery. Dentoalveolar applications, such as carious lesion detection and characterization, assessment of the three-dimensional nature of periodontal bone topography, and various endodontic applications are less known and not as thoroughly studied. This article explores and assesses in vivo and in vitro efforts to apply CBCT imaging to these more common dentoalveolar tasks. CBCT imaging, like its medical counterpart, can be seen as a highly useful and, in some instances, indispensable part of the dental imaging armamentarium.

Radiological assessment of periapical status using the periapical index: comparison of periapical radiography and digital panoramic radiography.

AIM: To compare the use of periapical radiographs and digital panoramic images displayed on monitor and glossy paper in the assessment of the periapical status of the teeth using the periapical index (PAI). METHODOLOGY: A total of 86 subjects were examined. All participants underwent a full-mouth radiographic survey (14 periapical radiographs) and a panoramic radiography. The periapical status, using the PAI score, of all appraised teeth was assessed. RESULTS: Periapical radiographs allowed the assessment of the periapical status of 87% of teeth using the PAI. On the contrary, digital radiography had a significantly reduced potential to allow assessment of the periapical status (P<0.01). Only 57.6% and 34.1% of teeth could be appraised using digital panoramic images displayed on monitor and glossy paper respectively (P<0.01). The total percentage of teeth with periapical pathosis was five fold higher when assessed with digital panoramic images displayed on glossy paper compared with periapical radiographs (P<0.01). CONCLUSIONS: Teeth were best viewed on periapical radiographs except maxillary second and third molars, which were better viewed in orthopantomograms. Orthopantomograms on screen were scorable more often than when on printed images. Apical periodontitis was scored more often on paper than on screen, and more often on screen than in periapical radiographs.

Radiographic assessment of dental health in middle-aged men following sudden cardiac death.

Poor oral health has been suggested to be a risk factor for myocardial infarction. To study if dental pathology might predispose to pre-hospital sudden cardiac death, and using a sum index of panoramic tomography findings, we compared the oral health of middle-aged (33-69 yrs) male victims (Helsinki Sudden Death Study) of sudden cardiac death (n = 117) with that of controls, who died of non-cardiac diseases (n = 63) or suffered unnatural sudden death (n = 120). The mean number of teeth was 15.2, and 17.4% of the men were edentulous. Frequent age-associated findings in dentate victims were fillings (79.9%), horizontal bone loss (72.1%), periapical lesions (45.6%), residual roots (38.2%), and vertical pockets (30.9%). In multivariate analysis with coronary heart disease risk factors and number of teeth as covariates, poor oral health was associated (p = 0.053) with the risk of sudden cardiac death along with age, smoking, and body mass index. This association was especially strong (p = 0.009) among victims < 50 yrs.

[Clinical and radiographic assessment of single-appointment endodontic treatment in teeth with chronic periapical lesions]. / Avaliação clínica e radiográfica do tratamento endodôntico em sessão única de dentes com lesões periapicais crônicas.

The aim of this study was to evaluate the incidence of postoperative pain and the type of periapical repair, after one-appointment endodontic treatment in asymptomatic patients who presented with pulpal necrosis and radiographically visible chronic periapical lesions. For that, after biomechanical preparation through the step down followed by the step back technique, aided by copious irrigation with 5.0% sodium hypochlorite solution, the filling of the root canals was carried out through the conventional technique, with gutta-percha cones and zinc oxide-eugenol cement. In the immediate postoperative period, 16.6% of all patients presented with spontaneous pain, although the incidence of severe pain--flare-ups--was 3.3%. After twelve months, all patients were asymptomatic and free of fistula, nevertheless only 46.4% exhibited complete resolution of the radiolucent periapical areas. Therefore, in a medium term, the one-appointment endodontic treatment showed 100% of clinical success, but showed a reduced rate of radiographic success.

[Assessment of 3 radiographic methods (conventional periapical, digital periapical, and panoramic) ni the diagnosis of artificially produced periapical lesions]. / Avaliação de três métodos radiográficos (periapical convencional, periapical digital e panorâmico) no diagnóstico de lesões apicais produzidas artificialmente.

This research was carried out in order to evaluate three radiographic methods--conventional periapical, digital periapical and panoramic--in the diagnosis of artificially produced periapical lesions. For this purpose, 5 mandibles, with lesions produced by means of spherical drills of different sizes, were used. The research was divided into five distinct phases, as follows: phase Z (initial)--characterized by the absence of lesion; phase R--lesion produced with a number 6 drill; phase J--lesion produced with a number 8 drill; phase D--lesion produced with a number 10 drill; and phase H--lesion reaching the vestibular cortex. The lesions were produced in quadrants. Radiographs were made after each phase and analyzed by 4 experts in radiology. For the digital system there was statistically significant difference in phase R (in the region of incisors) and in phase H (in the region of premolars). In the region of molars there was statistically significant difference in phase D for panoramic radiography. It must be pointed out that panoramic radiography produced the less effective results in phase H.

The assessment of the endodontically treated tooth.

This paper reviews the assessment of success and failure following endodontic treatment and highlights the fact that many referrals for specialist management of endodontic failure do not take into consideration established guidelines in this important area.

Endodontic retreatment. Aspects of decision making and clinical outcome.

Epidemiological surveys have reported that 25%-35% of root filled teeth are associated with periapical radiolucencies. Descriptive studies have demonstrated that clinicians' decision making regarding such teeth are subject to substantial variation. A coherent model to explain the observed variation has not been produced. In the present thesis a "Praxis Concept theory" was proposed. The theory suggests that dentists perceive periapical lesions of varying sizes as different stages on a continuous health scale. Interindividual variations can then be regarded as the result of the choice of different cut-off points on the continuum for prescribing retreatment. In the present study experiments among novice and expert decision makers gave evidence in favour of the theory. Data also suggested that the choice of retreatment criterion is affected by values, costs of retreatment and technical quality of original treatment. From a prescriptive point of view, the presence of a persistent periapical radiolucency has often been used as a criterion of endodontic "failure" and as an indication for endodontic retreatment. As an alternative decision strategy, the use of decision analysis has been proposed. Logical display of decision alternatives, values of probabilities, utility values (U-values) of the different outcomes and calculation of optimal decision strategy are features of this theory. The implementation of this approach is impeded by the uncertainty of outcome probabilities and lack of investigations concerning U-values. U-values of two periapical health states in root filled teeth (with and without a periapical lesion respectively) were investigated in a group of 82 dental students and among 16 Swedish endodontists. Two methods were used to elicit U-values: Standard gamble and Visual Analogue Scale. Large interindividual variation for both health states were recorded. The difference in U-values between the two health states was found to be statistically significant regardless of assessment method. Compared with Standard gamble Visual Analogue Scale systematically produced lower ratings. U-values were found to change considerably in both the short and long-term. Any significant correlation between endodontists' U-values and retreatment prescriptions could not be demonstrated. Surgical and nonsurgical retreatment were randomly assigned to 95 "failed" root filled teeth in 92 patients. Cases were followed clinically and radiographically for four years postoperatively. At the 12-month recall a statistically significant higher healing rate was observed for teeth retreated surgically. At the final 48-month recall no systematic difference was detected. Patients were found to be more subject to postoperative discomfort when teeth were retreated surgically compared with nonsurgically. Consequently, surgical retreatment tended to be associated with higher indirect costs than a nonsurgically approach. In the final part of the thesis it is argued that retreatment decision making in everyday clinical practice normally should be based on simple principles. It is suggested that in order to achieve the best overall consequence a periapical lesion in a root filled tooth that is not expected to heal should be retreated. Arguments to withhold retreatment should be based on (i) respect for patient autonomy, (ii) retreatment risks or (iii) retreatment costs.

Longitudinal radiological study of the oral health parameters in an elderly Finnish population.

In the oldest elderly, an increase in the number of remaining teeth may increase oral infection foci. The aim of this follow-up study was to examine the radiologically detected oral health condition of a group of home-living elderly in Helsinki at 5-year intervals. The population of this study comprised 103 home-living elderly people, all participants of the population-based Helsinki Aging Study. Panoramic radiography supplemented by intraoral radiographs was performed on all these participants at the Institute of Dentistry, University of Helsinki, in 1990-1991. Follow-up radiographic examination was completed in 1995-1996. Mean number of teeth decreased during the follow-up period from 13.2 +/- 9.0 to 12.5 +/- 9.2 (P= 0.0001). Mean number of teeth with periapical lesions decreased in men from 1.3 +/- 1.4 to 0.6 +/- 0.9 (P = 0.007), but no differences in number of teeth with periapical findings were observed in women. There were relatively few changes in the subjects' radiographic periodontal findings. However, fewer teeth with vertical bone pockets >1-3 mm deep were found in the follow-up study than 5 years earlier (0.6 +/- 1.2 vs 1.1 +/- 1.8; P= 0.0008). In both the baseline and the follow-up studies the radiographic findings occurred in the subjects who had retained more natural teeth. In the follow-up study, 68% of the subjects had radiographically detected signs of chronic oral infection foci. It may be concluded that radiographically detected oral health parameters remain relatively unchanged, but treatment need is higher among those who have successfully retained their natural dentition into old age.