Showing papers in "International Endodontic Journal in 2000"

An overview of nickel-titanium alloys used in dentistry.

Abstract: The nickel-titanium alloy Nitinol has been used in the manufacture of endodontic instruments in recent years. Nitinol alloys have greater strength and a lower modulus of elasticity compared with stainless steel alloys. The super-elastic behaviour of Nitinol wires means that on unloading they return to their original shape following deformation. These properties are of interest in endodontology as they allow construction of root canal instruments that utilize these favourable characteristics to provide an advantage when preparing curved canals. This review aims to provide an overview of Nitinol alloys used in dentistry in order for its unique characteristics to be appreciated.

Complications during root canal irrigation--literature review and case reports.

Abstract: Hulsmann M, Hahn W. Complications during root canal irrigation ‐ literature review and case reports. International Endodontic Journal , 33 , 186‐193, 2000. Literature review and case reports The liter ature concerning the aetiology, symptomatology and therapy of complications during root canal irrigation is reviewed. Three cases of inadvertent injection of sodium hypochlorite and hydrogen peroxide beyond the root apex are presented. Clinical symptoms are discussed, as well as preventive and therapeutic considerations.

Inactivation of local root canal medicaments by dentine: an in vitro study.

Abstract: Aims The aim of the study was to investigate the inactivation by dentine of the antibacterial activity of various commonly used local root canal medicaments. Methodology The medicaments tested were saturated calcium hydroxide solution, 1% sodium hypochlorite, 0.5% and 0.05% chlorhexidine acetate, and 2/4% and 0.2/0.4% iodine potassium iodide. Dentine was sterilized by autoclaving and crushed into powder with a particle size of 0.2–20μm. Aliquots of dentine suspension were incubated with the medicaments in sealed test tubes at 378C for 24 h or 1 h before adding the bacteria. In some experiments bacteria were added simultaneously with dentine powder and the medicament. Enterococcus faecalis A197A was used as a test organism. Samples for bacterial culturing were taken from the suspensions at 5 min, 1 h and 24 h after adding the bacteria. Results Dentine powder had an inhibitory effect on all medicaments tested. The effect was dependent on the concentration of the medicament as well as on the length of the time the medicament was preincubated with dentine powder before adding the bacteria. The effect of calcium hydroxide on E. faecalis was totally abolished by the presence of dentine powder. Similarly, 0.2/0.4% iodine potassium iodide lost its effect after preincubation for 1 h with dentine before adding the bacteria. The effect of 0.05% chlorhexidine and 1% sodium hypochlorite on E. faecalis was reduced but not totally eliminated by the presence of dentine. No inhibition could be measured when full strength solutions of chlorhexidine and iodine potassium iodide were used in killing E. faecalis. Conclusions The dentine powder model appears to be an efficient tool for the study of interactions between local endodontic medicaments, dentine, and microbes.

Periapical status and quality of root fillings and coronal restorations in a Danish population.

Abstract: Kirkevang L-L, Orstavik D, Horsted-Bindslev P, Wenzel A. Periapical status and quality of root fillings and coronal restorations in a Danish population. International Endodontic Journal , 33 , 509‐515, 2000. Aim The aim of this study was to investigate the quality of endodontic and coronal restorations and the association with periapical status in a Danish population. Methodology A total of 614 randomly selected individuals (20 ‐ 60+ years of age) from Aarhus County had a full-mouth radiographic examination. The quality of endodontic and coronal restorations and the periapical status of endodontically treated teeth were assessed by radiographic criteria. Root fillings were categorized as ‘adequate’ or ‘inadequate’ with regard to root filling length and lateral seal. Coronal restorations were categorized into ‘adequate’ and ‘inadequate’, defined by the absence or presence of radiographic signs of overhangs or open margins. Results were analysed statistically using the chi-squared test. Results The total number of endodontically treated teeth was 773, and 52.3% had apical periodontitis (AP). Root-filled teeth with an adequate lateral seal had a lower incidence of AP than teeth with an inadequate seal (44.3% vs. 57.8%), and teeth with an adequate root filling length were associated with a better periapical status than teeth with inadequate length of the root filling (42.0% vs. 67.6%). Similarly, adequate coronal restorations were associated with better periapical status than inadequate restorations (48.0% vs. 63.9%). When both root filling and coronal restoration quality were assessed, the incidence of AP ranged from 31.2% (optimal quality) to 78.3% (all parameters scored as inadequate). Conclusions Inadequate root canal and coronal restorations were associated with an increased incidence of AP.

Periapical health related to the quality of root canal treatment in a Belgian population

Abstract: Aim The aim of this study was to collect data on the prevalence and technical standard of root canal treatment as well as the prevalence of apical periodontitis in Belgium. Methodology The panoramic radiographs of 206 Belgian adults attending the Dental School of the University Hospital of Gent were examined for endodontic treatment, periapical conditions and coronal restorations. Results Of the 4617 teeth examined, 6.8% were endodontically treated. Periapical radiolucencies were found in 6.6% of all teeth and in 40.4% of the endodontically treated teeth. More than half of the root-filled teeth (56.7%) were scored inadequate on the basis of a criterion evaluating the level of the root canal filling. Conclusion The endodontic treatment need of this Belgian subpopulation was great and the technical standard of root canal treatment disappointing. The findings indicate that there is still a substantial need for postgraduate endodontic education in Belgium and a need for specialists in endodontology.

Lasers in endodontics: a review.

Abstract: Since the development of the ruby laser by Maiman in 1960 and the application of the laser for endodontics by Weichman in 1971, a variety of papers on potential applications for lasers in endodontics have been published. The purpose of this paper is to summarize laser applications in endodontics, including their use in pulp diagnosis, dentinal hypersensitivity, pulp capping and pulpotomy, sterilization of root canals, root canal shaping and obturation and apicectomy. The effects of laser on root canal walls and periodontal tissues are also reviewed. The essential question is whether a laser can provide equal or improved treatment over conventional care. Secondary issues include treatment duration and cost/benefit ratio. This article reviews the role of lasers in endodontics since the early 1970s, summarizes many research reports from the last decade, and surmises what the future may hold for lasers in endodontics. With the potential availability of many new laser wavelengths and modes, much interest is developing in this promising field.

Influence of calcium hydroxide intracanal dressings on the prognosis of teeth with endodontically induced periapical lesions.

Abstract: Weiger R, Rosendahl R, Los t C. Influence of calcium hydroxide intracanal dressings on the prognosis of teeth with endodontically induced periapical lesions. International Endodontic Journal, 33, 219-226, 2000. Aim This prospective clinical study explored the influence of calcium hydroxide as an interappointment dressing on the healing of periapical lesions associated with pulpless teeth that had not been endodontically treated previously. This was achieved by comparing the prognosis after a two-visit root canal treatment with that following a one-visit treatment. Methodology Seventy-three patients were recruited having one tooth with an endodontically induced lesion. Of these patients, 67 could be re-examined. Calcium hydroxide was placed in the instrumented root canals of 31 teeth for at least one week and the treatment finished at the second visit. Thirty-six teeth were root canal treated at one visit. The criteria for success were the absence of signs and symptoms indicating an acute phase of periapical periodontitis and radiographically a periodontal ligament space ofnormal width. Methods for event time analysis were used to evaluate and compare the prognosis of both treatment approaches. Results The probability that complete periapical healing will take place increased continuously with the length of the observation period. In both treatment groups the likelihood that the root canal treatment yields a success within an observation time of five years exceeded 90%. A statistically significant difference between the two treatment groups could not be detected. Conclusions From a microbiological perspective, one-visit root canal treatment created favourable envir- onmental conditions for periapical repair similar to the two-visit therapy when calcium hydroxide was used as antimicrobial dressing. One-visit root canal treatment is an acceptable alternative to two-visit treatment for pulpless teeth associated with an endodontically induced lesion.

Prognosis in periradicular surgery: a clinical prospective study.

Abstract: Zuolo ML, Ferreira MOF, Gutmann JL. Prognosis in periradicular surgery: a clinical prospective study. International Endodontic Journal, 33, 91–98, 2000. Aim The purpose of this prospective study was to evaluate the prognosis of periradicular surgery using well-defined case selection and a rigorous surgical protocol. Methodology Teeth to be treated surgically demonstrated a periradicular lesion of strictly endodontic origin with or without clinical signs and symptoms of inflammation. A total of 114 teeth were treated. Following the reflection of a full mucoperiosteal tissue flap, residual soft tissues were curetted, root ends were resected with a fine high-speed diamond bur, root-end cavities were prepared ultrasonically with diamond tips, and IRM root-end fillings were placed. Cases were followed clinically and radiographically for a period ranging from 1 to 4 years. Results The results of this study showed 91.2% success out of a total of 102 teeth available for follow-up, based on accepted parameters of evaluation. Cases were considered successful if there were no clinical signs or symptoms present and there was radiographic evidence of complete or incomplete healing (scar tissue). Factors related to case selection, parameters of healing and surgical technique are discussed in relation to the success rate identified in this prospective study. Conclusions Adherence to a strict endodontic surgical protocol and the use of contemporary techniques and materials will result in a predictably successful outcome in a wide range of teeth.

A comparison of the relative efficacies of four hand and rotary instrumentation techniques during endodontic retreatment.

Abstract: Aim The purpose of this study was to quantify the amount of remaining gutta-percha/sealer on the walls of root canals when two engine-driven instruments (Quantec and ProFile) and two hand instruments (K-file and Hedstrom file) were used to remove these materials. The amount of apically extruded debris and the time required for treatment were also recorded. Methodology One hundred extracted mandibular premolars were prepared using a modified step-back, flare technique and obturated with the lateral condensation technique. After repreparation with the test instruments, the specimens were cut transversally at the cervical, middle and apical thirds with steel discs and the three sections were split longitudinally. The amount of residual debris on the canal walls in each section was examined using a stereomicroscope. Results In all groups the cervical and middle thirds showed no debris. In the apical third, obturating material was observed in some specimens. No statistically significant difference was found between the two groups for incidence of debris, although the Hedstrom group showed a greater number of samples with remaining gutta-percha/sealer. When analysing dirty specimens only, there was a statistically significant difference between the four groups (P < 0.01) with the Hedstrom group having significantly less length of canal wall with remaining obturation material than the Quantec group. There was no significant difference amongst the groups for weight of extruded debris. However, there was a significant difference amongst the groups for mean treatment time with the Hedstrom file group requiring significantly less time than the Quantec group (P < 0.001); no significant differences were found between the other groups. Six instruments fractured in the Quantec group, four in the ProFile group, two in the Hedstrom group and two in the K-type group. Conclusions The results showed that overall, all instruments may leave filling material inside the root canal. During retreatment there is a risk of instrument breakage, especially rotary instruments.

Shaping ability of Hero 642 rotary nickel-titanium instruments in simulated root canals: Part 1.

Abstract: Aim To determine the general efficacy and shaping ability of Hero 642 nickel–titanium rotary instruments during the preparation of simulated canals. Part 1 of this two-part report describes the efficacy of the instruments in terms of three-dimensional canal form. Methodology A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by Hero 642 instruments using a crown-down preparation sequence. The efficacy of the instruments was assessed in terms of preparation time, instrument failure, canal blockages and loss of canal length. Intra-canal impressions were taken of the prepared canals in order to assess three-dimensional canal form. Results The mean time for canal preparation was 8.6 min and was influenced significantly (P < 0.05) by canal shape. Two instruments fractured and eight instruments deformed; significant differences were observed between canal shapes (P < 0.05). All of the canals remained patent. Fifteen canals (39.5%) maintained the correct working distance, 15 lost distance and eight canals gained length. Examination of intracanal impressions demonstrated that the majority of canals (79%) had apical stops; canal shape had a significant influence (P < 0.001) on the quality of apical stops. With one exception all canals had smooth canal walls and all of the canals showed good flow characteristics. Taper was poor in 30 canals (79%) and good in eight canals (21%). Conclusions Hero 642 rotary nickel–titanium instruments prepared simulated canals rapidly but with a three-dimensional form that lacked adequate taper.

Root canal anatomy of maxillary first and second permanent molars

Abstract: AIM The aim of this investigation was to study the root canal anatomy of maxillary first and second molar teeth from an Irish population sample using a clearing technique. METHODOLOGY Eighty-three extracted permanent maxillary right first molars and 40 permanent right maxillary second molars were included in this investigation. The specimens were demineralized and then cleared using methyl salicylate. The following observations were made: number of roots, prevalence of fusion, types of root canals using Vertucci's classification, presence and position of lateral canals, presence and position of transverse anastomoses, number and position of apical foramina and the frequency of occurrence of apical deltas. RESULTS Eleven per cent of maxillary first molars and 43% of maxillary second molars had fused roots. A total of 78% of mesiobuccal roots in maxillary first and 58% in maxillary second molars had two canals. Sixty-two per cent of maxillary first and 50% of maxillary second molars had two apical foramina. There was a significant inverse relationship between age and the occurrence of two canals and between age and the occurrence of transverse anastomoses in both tooth morphotypes (P < or = 0.05). CONCLUSIONS It is concluded that a significant proportion of the first and second molar specimens studied had two canals in the mesiobuccal root (78% and 58%, respectively) and that the occurrence of two canals and transverse anastomoses decreased significantly with increasing age.

Cyclic fatigue of ProFile rotary instruments after clinical use.

Abstract: Aim The purpose of this study was to evaluate cyclic fatigue of .06 ProFile Ni-Ti rotary instruments after clinical use in molar teeth. Methodology In group 1, instruments size 40–15 were used in a crown-down technique using 2.5% NaOCl as an irrigant. Fifty-two molars were included and 13 sets of Profile Ni-Ti rotary instruments were used. Each set of instruments was used in four molars, and was steam autoclaved before each use. Group 2 (10 sets of new ProFile Ni-Ti rotary instruments) was the control group. Cyclic fatigue was tested by rotating the instruments in a 908 metallic tube until they broke. Results One-way analysis of variance did not show any statistically significant differences amongst the files from both groups regarding cyclic fatigue. Conclusions It was concluded that sterilization and clinical use in the presence of NaOCl did not lead to a decrease in the number of rotations to breakage of the files.

Sealer distribution in root canals obturated by three techniques

Abstract: Wu M-K, Ozok AR, Wesselink PR. Sealer distribution in root canals obturated by three techniques. International Endodontic Journal , 33 , 340‐345, 2000. Aim The aim of this study was to observe sealer distribution in root canals filled by different root filling techniques. Methodology AH26 (0.05 mL) dyed with carbon black powder was placed into the prepared root canals of maxillary central incisors using a lentulo spiral. Thereafter the canals were obturated using three different gutta-percha root-filling techniques. Horizontal sections were cut in the apical and middle portions of the filled canals. Images of the cross sections were scanned and the percentage of sealer coated canal perimeter (PSCP) was measured using a computer digital imaging system. Results At 3 mm from the apex, the PSCP after lateral condensation was similar to that after vertical condensation ( P > 0.05). At 6 mm from the apex, however, the PSCP was significantly higher after lateral condensation than after vertical condensation ( P < 0.05). At both levels the PSCP was significantly higher after single cone (no condensation) than after the other two condensation techniques ( P < 0.0001). Conclusions Sealer may be removed from the canal wall by the condensation procedures.

Apical inflammatory root resorption: a correlative radiographic and histological assessment

Abstract: AIM: To assess the reliability of routine single radiographs in the diagnosis of inflammatory apical root resorption by correlating the radiographic and histological findings. METHODOLOGY: The material comprised serial and step serial sections of plastic-embedded root-apices with attached apical periodontitis lesions that were prepared for a previous study and the diagnostic radiographs. The histological sections of 114 specimens were analysed by light microscopy and categorized into three groups: (i) those without any resorption (0); (ii) those with moderate resorption (+); and (iii) those with severe resorption (+ +). The radiographs were examined by a separate examiner and graded with a similar categorization of no resorption (0); moderate (+); and severe (+ +) apical resorption. RESULTS: Radiographically, 19% of the teeth were diagnosed as having apical inflammatory root resorption, whereas histologically, 81% of the teeth revealed apical inflammatory root resorption. A correlative radiographic and histological assessment (n = 104) revealed a coincidence of diagnosis in 7% of the specimens and noncoincidence of diagnosis in 76% of the specimens. CONCLUSIONS: The results indicate that routine single radiographs are not sufficiently accurate or sensitive to consistently diagnose apical root resorptive defects developing as a consequence of apical periodontitis.

Evaluation of apical sealing of three endodontic sealers.

Abstract: De Almeida WA, Leonardo MR, Tanomaru Filho M, Silva LAB. Evaluation of apical sealing of three endodontic sealers. International Endodontic Journal, 33, 25–27, 2000. Aim The apical sealing ability of three different endodontic sealers was evaluated in extracted teeth using dye penetration. Methodology The root canals of 99 extracted human maxillary central incisors were prepared sequentially 2mm beyond the apical foramen with a size 55 Nitiflex file. The teeth were divided into three experimental groups and obturated by lateral condensation of cold gutta-percha and one of the following sealers: group 1, zinc oxide and eugenol sealer (Fill Canal); group 2, glass ionomer sealer (Ketac-Endo) and group 3, epoxy resin sealer (AH Plus). The teeth were covered with nail varnish to within 1mm of the apical foramen and immersed in 2% methylene blue in a reduced pressure environment for 24h. After this period, the teeth were washed and cut longitudinally for apical leakage analysis. The values were obtained from the maximum depth of leakage as well as the average between the maximum and minimum values observed for each group. Results Statistical evaluation of the results showed no significant difference in the leakage between Fill Canal and Ketac-Endo (P >0.05). Leakage with AH Plus was significantly less (P <0.01) than with the other sealers. Conclusions All three sealers allowed some leakage to occur. Leakage with AH Plus was significantly different than with Fill Canal or Ketac-Endo.

Diminished leakage along root canals filled with gutta-percha without sealer over time: a laboratory study.

Abstract: Wu M-K, Fan B, Wesselink PR. Diminished leakage along root canals filled with gutta-percha without sealer over time: a laboratory study. International Endodontic Journal, 33, 121‐125, 2000. Aim The aim of this study was to investigate the long-term seal of gutta-percha (GP) without sealer. Methodology Extracted human maxillary central incisors were prepared and obturated using heat- or chloroform-softened GP only, or GP in combination with a root canal sealer. Leakage along root fillings was measured at 48 h and after a period of 6 months using a fluid transport model. Results At 48 h the GP-filled roots without sealer leaked more than the control roots filled with GP and sealer (P 0.05). Conclusions The long-term seal of root fillings is affected by the volume change of both GP and sealer. Leakage reduction due to expansion of GP may compensate to a certain extent for leakage that may occur from sealer dissolution.

Use of rubber dam and irrigant selection in UK general dental practice.

Abstract: Aim To evaluate factors which influence rubber dam use and irrigant selection in UK National Health Service (NHS) endodontics. Methodology A postal survey was conducted amongst two age cohorts of dentists, representing all of the 1970–73 (older) and 1990–93 (younger) graduates of two northern English dental schools (n = 643). Key and supplementary questions were posed on levels of rubber dam use, irrigant selection, and factors influencing practice in NHS endodontics. After manual checking, validated (dual) entry of responses was made to a flat ASCII data file before analysis with SPSS software. The threshold for statistical significance was set at the 95% probability level. Results Eighty-five per cent of the valid sample responded to the questionnaire. Regardless of age and qualifying school, less than one-fifth of dentists always or frequently used rubber dam, whilst 60% never used it. Qualifying school had a significant influence on rubber dam use, whilst age had a variable influence. Major disincentives to the use of rubber dam included the perception that patients do not like it, that the NHS fee was inadequate to justify its use, that it took too long to apply, and that dentists had received inadequate training. Frequent users of rubber dam were significantly less likely to cite these disincentives than nonusers. Overall, local anaesthetic solution was the most common endodontic irrigant. Irrigant choice was strongly linked to rubber dam use, and to graduation cohort. Seventy-one per cent of rubber dam users irrigated with sodium hypochlorite, compared with only 38% of nonusers. This pattern was reversed for local anaesthetic irrigation. Younger graduates were significantly more likely to irrigate with local anaesthetic solution than their older counterparts, and the younger graduates of one school showed a highly significant increase in the use of chlorhexidine. Conclusions 1) The majority of UK Health Service dentists never use rubber dam isolation in endodontic treatment. 2) Qualifying school has a significant impact on rubber dam use, and irrigant selection. 3) Use of rubber dam has a significant association with irrigant choice in endodontics.

Radiographic evaluation of periapical healing after obturation of infected root canals: an in vivo study

Abstract: Katebzadeh N, Sigurdsson A, Trope M. Radiographic evaluation of periapical healing after obturation of infected root canals: an in vivo study. International Endodontic Journal, 33, 60–65, 2000. Aim To radiographically compare periapical repair of roots with infected root canals obturated in one-step or with calcium hydroxide (Ca(OH)2) intracanal medication in two steps. Methodology Standardized preoperative periapical radiographs were taken of 72 roots of vital dogs' teeth. All roots were then aseptically instrumented to ISO size 45. As negative controls, 12 roots were aseptically obturated. The remaining roots were infected with dental plaque and closed. Six weeks later, apical periodontitis was radiographically confirmed in the infected roots. The roots were divided into the following groups: group 1, one-step (n=24); roots were irrigated with 10 cc saline, obturated, and permanently restored. Group 2, Ca(OH)2 (n=24); roots were treated as in group 1, except that after saline irrigation Ca(OH)2 medicament was placed in the canal 1 week before obturation. Group 3, positive control (n=12); the roots were irrigated with saline, access permanently closed but canals not obturated. Group 4, negative control (n=12); previously aseptically obturated roots were permanently restored. After 6 months, standardized postoperative radiographs were obtained. Three independent evaluators blinded to the treatment groups evaluated the preoperative and postoperative radiographs. The evaluators were instructed to rate each root, based on changes on the radiographs, as failed, improved or healed. Results Radiographically, the percentage of cases that completely healed were similar for the one-step and Ca(OH)2 groups (35.3% vs. 36.8%). However, the Ca(OH)2 group had fewer failed cases (15.8% vs. 41.2%) and more improved cases (47.4% vs. 23.5%) than the one-step group. Conclusion Power statistics demonstrated that at 43 cases per group, Ca(OH)2 treatment would be statistically superior to one-step treatment. We consider this number to be clinically important.

Shaping ability of Hero 642 rotary nickel–titanium instruments in simulated root canals: Part 2

Abstract: Aim To determine the shaping ability of Hero 642 nickel–titanium rotary instruments during the preparation of simulated canals. Methodology A total of 40 simulated root canals made up of four different shapes, in terms of angle and position of curvature, were prepared by Hero 642 instruments using a crown-down preparation sequence. Pre- and postoperative images of the canals were taken using a video camera attached to a computer with image analysis software. The pre- and postoperative views were superimposed to highlight the amount and position of material removed during preparation. This report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and overall postoperative shape. Results Four zips and four elbows were created during preparation, all in canals with 40°, 12 mm curves. No perforations or danger zones were created. Highly significant differences (P < 0.001) were apparent between the canal shapes in total canal width at the apex and beginning of the curve, and in the amount of resin removed from the inner and outer aspects of the curve at the orifice. Canal transportation was most frequently directed toward the outer aspect of the curve at specific points along the canal, except at the orifice, where it was apparent that canals with 20° curves transported toward the inner. Overall, mean absolute transportation was always less than 0.15 mm; however, significant differences occurred between canal shapes at the end-point (P < 0.01), apex of the curve (P < 0.01) and at the orifice (P < 0.01). Conclusions Under the conditions of this study, Hero 642 rotary nickel–titanium instruments created canals with few aberrations and no perforations. The relatively high proportion of aberrations in canals with short, acute curves may indicate that instruments with increased taper should be used with caution at or near the full working distance. Further research in real teeth is necessary to elucidate the full potential of these new rotary instruments for use in root canal preparation.

Effectiveness of 1 mol L-1 citric acid and 15% EDTA irrigation on smear layer removal.

Abstract: Di Lenarda R, Cadenaro M, Sbaizero O. Effectiveness of 1 mol L− 1 citric acid and 15% EDTA irrigation on smear layer removal. International Endodontic Journal, 33, 46–52, 2000. Aim The aim of this study was to evaluate in vitro the cleansing and smear layer removal capability of alternate canal irrigation with citric acid and NaOCl. Methodology Eighty-one teeth were divided into three groups on the basis of the type of instrumentation, namely, manual stainless steel, Ni-Ti mechanized ProFile .04 taper or MACXim. The groups were further divided on the basis of irrigation protocol: 5% NaOCl alone, NaOCl alternated with 1 mol L−1 citric acid solution or a combination of 15% EDTA and Cetrimide solution. After longitudinal sectioning, dentinal walls were microphotographed with scanning electron microscopy at ×300 and ×1000 magnifications. Qualitative and quantitative cleansing level evaluations were performed using computerized image analysis software. Data were statistically evaluated using Kruskal–Wallis analysis and t-test. Results Qualitative evaluation at ×300 and ×1000 showed no statistically significant differences in cleansing ability between citric acid, EDTA and NaOCl groups. Quantitative evaluation of smear layer removal, measured as open tubules/total dentinal surface ratio, showed that 1 mol L−1 citric acid solution was comparable to EDTA (11.97% vs. 10.36%) (NS); in samples treated with ProFile .04 taper instruments citric acid was most effective (16.17%), whilst in the group treated with manual instrumentation EDTA and Cetrimide were the most effective (11.94%). Specimens irrigated with 5% NaOCl demonstrated significantly more cleansing than those obtained in the other two groups (P <0.001). Conclusions 1 mol L−1 citric acid solution was as effective in removing smear layer as EDTA, but was superior in specimens treated with ProFile .04 taper instruments.

The effects of Ledermix paste on discolouration of immature teeth.

Abstract: Aim The aims of this study were to: (i) investigate the effects of Ledermix paste as an intracanal medicament on discolouration of immature teeth, (ii) examine whether the discolouring effects were related to the method of application, (iii) examine the effects of sunlight upon discolouration of immature teeth and (iv) compare the degree of discolouration between mature and immature teeth. Methodology The root canals of 45 immature extracted human teeth were prepared and filled with either Ledermix paste, calcium hydroxide [Ca(OH)2], or saline. In group 1, Ledermix paste was only placed apical to the cemento-enamel junction (CEJ) whilst in groups 2 and 3, the paste filled the entire pulp chamber and the root canals. In group 4, Ca(OH)2 paste and in group 5, saline (control) were allowed to fill the pulp chamber and the root canals. Group 3 teeth were kept in the dark and the other groups were exposed to daylight for 12 weeks. Results After 12 weeks, sunlight exposure had caused dark grey-brown staining in the Ledermix groups but this did not occur when the teeth were kept in the dark. More severe staining was noted when Ledermix paste filled the pulp chamber than when the paste was restricted to below the CEJ and when teeth were exposed to sunlight. When compared to the results of a similar study using mature teeth, the results were similar but the immature teeth were more severely stained than the mature teeth. The Ca(OH)2 paste caused an increase in lightness and yellowness in immature teeth. Conclusion It was concluded that Ledermix paste may cause discolouration of immature teeth. Such effects can be minimized if placement of the paste is restricted to below the gingival margin. Clinicians should ensure that Ledermix paste is not left on the walls of access cavities, especially in immature teeth.

The standardized‐taper root canal preparation – Part 1. Concepts for variably tapered shaping instruments

Abstract: Buchanan LS. The standardized-taper root canal preparation - Part 1. Concepts for variably tapered shaping instruments. International Endodontic Journal , 33 , 516-529, 2000. Aim To introduce the concept of variable taper instruments for predictable and ergonomic root canal preparation, and demonstrate the design features of Greater Taper files. Summary Optimal root canal shaping is difficult to practice and teach with traditional instruments. Instrument sequences are complex, with up to 18 instruments and 63 pro- cedural stages, providing almost limitless scope for poor results and iatrogenic error. In the first of six articles, Dr Buchanan describes the Variable Taper concept, which grew from such frustrations, and represents a new concept in file design. Milled from NiTi alloys in tapers of 0.06, 0.08, 0.10 and 0.12 mm mm -1 , with accessory files for wide canals, their design embodies the key shaping features of adequate coronal enlarge- ment, full deep shape, and predictable apical resistance form case after case. The ease and simplicity of their use is described, and enhanced cleaning and obturation outcomes discussed in relation to their unique design features. Key learning points • Canal preparation is difficult to practice and teach with traditional K-files and Gates Glidden drills. • Variable Taper files are designed to offer the optimal preparation features of adequate (not excessive) coronal enlargement, full deep shape, and apical resistance form in a simple instrument sequence. • Variable Taper technique is simple to master, and offers predictable cleaning and obturation outcomes, even in inexperienced hands.

A ‘one‐bottle’ adhesive system for bonding a fibre post into a root canal: an SEM evaluation of the post–resin interface

Abstract: Ferrari M, Mannocci F. A ‘one-bottle’ adhesive system for bonding a fibre post into a root canal: an SEM evaluation of the post-resin interface. International Endodontic Journal, 33, 397–400, 2000. Aim This report presents a case in which a ‘one-bottle’ adhesive system was used in combination with proprietary resin cement for bonding a fibre post. Methodology The fibre post was placed into the root canal of a fractured root under clinical conditions and then extracted 1 week later. Using scanning electron microscopy, half of the root was evaluated for hybrid layer formation and the other half for assessing resin tags. Results The investigation demonstrated that a ‘one-bottle’ system can infiltrate etched dentine. Conclusions The ‘one-bottle’ system tested in this study can create a mechanical interlocking with root etched dentine under clinical conditions.

Root canal treatment and general health: a review of the literature.

Abstract: Murray CA, Saunders WP. Root canal treatment and general health: a review of the literature. International Endodontic Journal,33, 1–18, 2000. Review The focal infection theory was prominent in the medical literature during the early 1900s and curtailed the progress of endodontics. This theory proposed that microorganisms, or their toxins, arising from a focus of circumscribed infection within a tissue could disseminate systemically, resulting in the initiation or exacerbation of systemic illness or the damage of a distant tissue site. For example, during the focal infection era rheumatoid arthritis (RA) was identified as having a close relationship with dental health. The theory was eventually discredited because there was only anecdotal evidence to support its claims and few scientifically controlled studies. There has been a renewed interest in the influence that foci of infection within the oral tissues may have on general health. Some current research suggests a possible relationship between dental health and cardiovascular disease and published case reports have cited dental sources as causes for several systemic illnesses. Improved laboratory procedures employing sophisticated molecular biological techniques and enhanced culturing techniques have allowed researchers to confirm that bacteria recovered from the peripheral blood during root canal treatment originated in the root canal. It has been suggested that the bacteraemia, or the associated bacterial endotoxins, subsequent to root canal treatment, may cause potential systemic complications. Further research is required, however, using current sampling and laboratory methods from scientifically controlled population groups to determine if a significant relationship between general health and periradicular infection exists.

Efficacy of Quantec rotary instruments for gutta-percha removal

Abstract: Aim The purpose of this study was to evaluate Quantec SC rotary instruments for removal of gutta-percha during retreatment of straight root canals. Methodology The root canals of 30 central incisors were instrumented and obturated before the teeth were randomly divided into three groups of 10 specimens each. Quantec SC rotary instruments and a 16 : 1 reduction handpiece powered by an electric motor were then used to remove the gutta-percha and sealer from canals. A different speed was used in each group (group 1, 350 r.p.m.; group 2, 700 r.p.m.; and group 3, 1500 r.p.m.). The followings factors were evaluated: time taken to reach working length, time for gutta-percha removal, total time, apically extruded material during filling removal and number of fractured instruments. Radiographs were taken after the filling removal and after the canal wall cleanliness was evaluated. The teeth were grooved longitudinally, divided, and the walls of each half were evaluated visually for cleanliness. They were then digitized using a scanner and the residual debris measured. Results The group in which a speed of 1500 r.p.m. was used had significantly faster treatment than the other groups. The amount of apically extruded material was not significantly different between groups. The only significant difference between groups for canal cleanliness was the middle third by radiographic evaluation: the group of 350 r.p.m. had larger amount of debris than the others. In group 1, six instruments fractured; in group 2, four instruments fractured; and in group 3, one instrument fractured. Conclusions Cleanliness and residual debris were equivalent for each group, but the use of 1500 r.p.m. speed was more rapid and fewer instruments fractured.

A comparison of two nickel-titanium instrumentation techniques in teeth using microcomputed tomography.

Abstract: Aim The aim of the study was to compare the shaping of root canals by two nickel–titanium instrumentation techniques using microcomputed tomography (MCT). Methodology Ten mandibular first molar teeth (30 canals) that had intact crowns and fully formed roots were scanned using MCT. Fifteen canals were instrumented using NiTiFlex hand files (Maillefer) using balanced force. The remainder were instrumented using prototype ProFile 0.04 Taper instruments (Dentsply) in a crown-down manner to an apical size ISO 25. The teeth were scanned again following instrumentation. The two instrumentation techniques were compared in a total of 27 canals. The area of dentine removed at pre-determined levels (2.0, 3.0, 4.5, 6.0, 7.5 mm) from the apex was measured. Transportation and centring were recorded. Images constructed at these levels were compared with video images of equivalent physical sections created after the second scan. The volume of dentine removed in the apical 7.5 mm of the root canals of each tooth was calculated and the different techniques compared. Rendered three-dimensional images were used to assess the preparations qualitatively. The time taken for preparation was recorded. Results There was no significant difference between hand instrumentation with NitiFlex files and machine instrumentation with prototype ProFile 0.04 Taper instruments for any of the variables tested. Conclusions Both techniques produced well centred and tapered preparations.

Cleaning effectiveness of root canal irrigation with electrochemically activated anolyte and catholyte solutions: a pilot study.

Abstract: Aim The aim of this study was to evaluate the potential of electrochemically activated (ECA) anolyte and catholyte solutions to clean root canals during conventional root canal preparation. Methodology Twenty extracted single-rooted human mature permanent teeth were allocated randomly into four groups of five teeth. The pulp chambers were accessed and the canals prepared by hand with conventional stainless steel endodontic instruments using a double-flared technique. One or other of the following irrigants was used during preparation: distilled water, 3% NaOCl, anolyte neutral cathodic (ANC) (300 mg L−1 of active chlorine), and a combination of anolyte neutral cathodic (ANC) (300 mg L−1 of active chlorine) and catholyte. The teeth were split longitudinally and the canal walls examined for debris and smear layer by scanning electron microscopy. SEM photomicrographs were taken separately in the coronal, middle and apical parts of canal at magnification of ×800 to evaluate the debridement of extra-cellular matrix and at a magnification of ×2500 to evaluate the presence of smear layer. Results Irrigation with distilled water did not remove debris in the apical part of canals and left a continuous and firm smear layer overlying compressed low-mineralized predentine. All chemically active irrigants demonstrated improved cleaning potential compared to distilled water. The quality of loose debris elimination was similar for NaOCl and the anolyte ANC solution. The combination of anolyte ANC and catholyte resulted in improved cleaning, particularly in the apical third of canals. The evaluation of smear layer demonstrated that none of the irrigants were effective in its total removal; however, chemically active irrigants affected its surface and thickness. Compared to NaOCl, the ECA solutions left a thinner smear layer with a smoother and more even surface. NaOCl enhanced the opening of tubules predominantly in the coronal and middle thirds of canals, whereas combination of ANC and catholyte resulted in more numerous open dentine tubules throughout the whole length of canals. Conclusions Irrigation with electrochemically activated solutions cleaned root canal walls and may be an alternative to NaOCl in conventional root canal treatment. Further investigation of ECA solutions for root canal irrigation is warranted.

Dissolution of root canal sealer cements in volatile solvents

Abstract: Whitworth JM, Boursin EM. Dissolution of root canal sealer cements in volatile solvents. International Endodontic Journal, 33, 19–24, 2000. Aim There are few published data on the solubility profiles of endodontic sealers in solvents commonly employed in root canal retreatment. This study tested the hypothesis that root canal sealer cements are insoluble in the volatile solvents chloroform and halothane. Methodology Standardized samples (n=5) of glass ionomer (Ketac Endo), zinc oxide-eugenol (Tubli-Seal EWT), calcium hydroxide (Apexit) and epoxy resin (AH Plus) based sealers were immersed in chloroform or halothane for 30 s, 1 min, 5 min and 10 min. Mean loss of weight was plotted against time of exposure, and differences in behaviour assessed by multiple paired t-tests (P <0.01). Results Clear differences were shown in the solubility profiles of major classes of root canal sealer cements in two common volatile solvents. In comparison with other classes of material, Ketac Endo was the least soluble in chloroform and halothane (P 0.01). Tubli-Seal EWT was significantly less soluble in halothane than chloroform (5.19% and 62.5% weight loss after 10 min exposure, respectively (P <0.01)). Its solubility in halothane was not significantly different from that of Apexit. AH Plus was significantly more soluble than all other materials in both chloroform and halothane (96% and 68% weight loss after 10 min exposure, respectively (P <0.01)). Conclusions There are significant differences in the solubility profiles of major classes of root canal sealer in common organic solvents. Efforts should continue to find a more universally effective solvent for use in root canal retreatment.

Identification of root canals in molars by tuned-aperture computed tomography.

Abstract: Aim To compare the tuned-aperture computed tomography system of imaging to conventional D-speed film for their ability to identify root canals in extracted human molars. Methodology Thirteen maxillary and six mandibular human molars were mounted in acrylic blocks to simulate clinical conditions by surrounding the teeth with a radiodense structure. The teeth were then imaged with conventional D-speed film using a standard paralleling technique, and with a modified orthopantomograph OP100 machine using a Schick no. 2 size CCD sensor as the image receptor. The source images were registered and TACT slices were generated using TACT Workbench™ Software. Three observers were asked to identify the number of canals in the conventional film group and the TACT image group using specific criteria. Ground truth was established by cross-sectioning the teeth at the coronal, middle, and apical thirds of the roots and directly visualizing the root canal morphology. Results TACT imaging detected 36% of 4th canals in maxillary molars and 80% of third canals in mandibular molars. Conventional film detected 0% of fourth canals in maxillary molars and 0% of third canals in mandibular molars. The differences in canal detection between the two techniques were statistically significant (Wilcoxon matched pair sign rank test, P = 0.001). Conclusions In this study, the TACT system of digital imaging was superior to conventional film in the detection of root canals in human molars and may be useful for the detection of root canals that will probably be missed upon conventional X-ray examination.

Comparative radiopacity of tetracalcium phosphate and other root‐end filling materials

Abstract: Aim This study compared the radiopacity of tetracalcium phosphate (TTCP) and 11 root-end filling materials relative to human dentine. Methodology Specimens of 2 mm thickness and a graduated aluminium stepwedge were placed on dental X-ray films and exposed to an X-ray beam. The optical densities of the specimens and aluminium steps were measured. The optical densities of the specimens were correlated to the equivalent thickness of aluminium with a regression analysis equation. The equation was used to calculate the equivalent aluminium thickness of each of the specimens. Results Nine of the materials were found to be of acceptable radiopacity (at least 2 mm Al more radiopaque than dentine). TCCP and two of the glass-ionomer compounds were found to have insufficient radiopacity to be radiographically distinguishable from human dentine. Conclusions All the materials were found to be distinguishable radiographically from dentine, except for Vitrebond, TTCP and Ketac-Fil. Amalgam was the most radiopaque material and Ketac-Fil was the least radiopaque material tested.