Ex vivo assessment of irrigant penetration and renewal during the cleaning and shaping of root canals: a digital subtraction radiographic study.

AIM: To assess radiographically irrigant penetration in the root canal system of curved roots during root canal shaping procedures ex vivo. METHODOLOGY: Thirty extracted mandibular molar teeth with moderate to severe curvature were used. A special aiming device was used to guarantee that each successive radiograph was taken with the same positioning. The mesiolingual canal of each tooth was instrumented using the ProTaper system. For each step of the shaping procedure, two irrigation modalities were repeated in the same order. Active irrigation consisted of a 0.5-mL flush of sodium diatrizoate solution (Hypaque 50%) immediately followed by agitation with a size 08 K-file. Passive irrigation consisted of a 0.5-mL flush of sodium hypochlorite solution delivered with a syringe through a 27-gauge notched tip needle. A digital radiograph was taken after each modality and stored on computer for subsequent digital subtraction and measures of the depths of irrigant penetration. Comparisons were performed within an analysis-of-variance framework in a repeated-measures approach. RESULTS: The penetration of irrigants was significantly greater for each successive step of the shaping procedure when the two modalities were analysed separately (P < 0.001). The difference between the two modalities was statistically significant for each step of the shaping procedure (P < 0.0001). CONCLUSIONS: Shaping root canals improved both penetration and exchange of irrigant inside the root canal system. Complete renewal of the solution was impossible to achieve with a conventional syringe delivery system and a limited volume of solution. Recapitulation with a K-file after flushing improved irrigant penetration.

Ex vivo assessment of irrigant penetration and renewal during the final irrigation regimen.

AIM: To assess irrigant penetration in curved canals after shaping procedures ex vivo. METHODOLOGY: Thirty extracted mandibular molars with moderate to severe root canal curvature were included. A special aiming device was used to guarantee that each successive radiograph was taken with the same positioning. The mesiolingual canal of each tooth was instrumented with ProTaper rotary files. Apical third preparation was completed with an F1 instrument before additional step-back enlargement using F2 then F3 instruments. For each apical taper, the teeth were submitted successively to active irrigation (AI) then to passive irrigation (PI). AI consisted of a 0.5 mL flush of sodium diatrizoate (Hypaque 50%) immediately followed by manual mechanical activation with a gutta-percha point. PI consisted in flushing the canals with sodium hypochlorite passively delivered with a syringe. A digital radiograph was taken after each modality. The influence of needle tip design, needle tip insertion level, irrigant volume, root canal taper and solution activation was assessed by using digital subtraction radiography and measures of the depths of irrigant penetration. Comparisons were performed within an analysis of variance framework in a repeated-measures approach. RESULTS: For PI, all the four explanatory variables 'apical taper', 'volume of irrigant used', 'corono-apical level of needle tip placement', 'needle tip design' had a significant (P < 0.005) influence on outcome of irrigation penetration. CONCLUSIONS: Only active irrigation allowed complete penetration and exchange of irrigating solution. For syringe irrigation alone, the level of needle tip placement in the canal was the most dominating factor.

The influence of previous non-surgical re-treatment on the outcome of endodontic surgery.

AIM: The aim of this study was to evaluate retrospectively if the outcome of periradicular surgery at four year follow-up can be affected by a previous orthograde re-treatment. METHODS: Eighty-one patients with 118 endodontically treated teeth who underwent surgical retreatment were divided in three groups. In group OA endodontic re-treatment was feasible and was attempted but, owing to the persistence of clinical symptoms and radiographic lesion, apical surgery was performed 4.8 ± 3.5 months later. In group OF endodontic re-treatment was feasible but was not performed, with subsequent apical surgery. In group ONF endodontic re-treatment was unfeasible, and apical surgery was performed. The treatment outcome was assessed four years postsurgery according to clinical and radiographic criteria. RESULTS: Seventy-six patients (112 teeth) could be evaluated at four years. In the ONF group five anterior maxillary teeth, belonging to three female patients, failed to heal. Three failures in three patients occurred in the OF group. No failure was recorded in the OA group. Three teeth in three patients were classified as uncertain healing in each group. The outcome of group OA resulted significantly better than the other treatment groups for both tooth-based and patient-based analysis. No significant effect was found as related to jaw, tooth type, presence of a post. A significant relation was found with gender (P=0.04). A negative correlation was found between outcome and age (Pearson's coefficient=-0.09), suggesting that the probability of failure increases with age. CONCLUSION: Orthograde re-treatment prior to apical surgery could be considered a valid alternative to tooth extraction and not an over-treatment.

The use of mineral trioxide aggregate in one-visit apexification treatment: a prospective study.

AIM: To assess the outcome of apexification using mineral trioxide aggregate (MTA). METHODOLOGY: Fifty-seven teeth with open apices on 50 patients referred for root canal treatment received an apexification procedure in one appointment with MTA by the same operator. Patients were recalled at 6 months, 12 months and every year thereafter. Blind to the treatment record, two examiners assessed the pre-treatment, post-treatment and control radiographs of the study patients in a dark room using a magnifier. Each apex visible on the radiographs was scored with the periapical index (PAI), and the size of the apical lesion was measured. The presence of an apical bridge was also noted. Kappa-Cohen test was used for examiners calibration. The paired t-test was used for statistical analysis of apical healing. RESULTS: Forty-three cases were included with at least 12 months follow-up. When considering the PAI score and the decrease in size of the apical lesion, healing occurred in 81% of cases. CONCLUSION: Apexification in one step using an apical plug of MTA can be considered a predictable treatment, and may be an alternative to the use of calcium hydroxide.

Ultrastructural and immunocytochemical characterization of immortalized odontoblast MO6-G3.

AIM: To investigate an immortalized murine odontoblast cell line as a potential alternative for experimental studies on dentinogenesis. METHODOLOGY: The MO6-G3 cell line was investigated morphologically over 3, 7, 11 and 42 days of culture, using histochemical localization of dentine sialoprotein (DSP), alkaline phosphatase (AP), type I collagen and actin filaments, histoenzymatic staining and biochemical investigation of AP and finally, transmission and scanning electron microscopy. RESULTS: Scanning electron micrographs showed elongated cells. Accordingly, a polarized organization of odontoblasts was observed by transmission electron microscopy, identifying distinct subcellular compartments as described in vivo. The secretion apparatus, which includes cisternae of rough endoplasmic reticulum, Golgi apparatus saccules and secretion vesicles and granules, was longitudinally organized in the supranuclear compartment ending distally in the secretory pole. A cellular process was observed. The investigation of the cytoskeleton network revealed that actin microfilaments were organized in parallel stress fibre oriented depending on the longitudinal axis of the cytoplasm. Immunofluorescent labelling showed a continuous expression of type I collagen, DSP and AP. A unipolar distribution characterized intracellular DSP immunoreactivity. Histoenzymology revealed AP active sites increasing from 3 to 11 days albeit with a moderate level of activity comparatively to the in vivo situation in dental cells. CONCLUSION: This cell line MO6-G3 not only showed the criteria of odontoblast phenotype as previously reported but also the characteristic morphodifferentiation pattern of polarized odontoblasts at the cellular level but with an apparent random distribution.

Multidisciplinary approach to the immediate esthetic repair and long-term treatment of an oblique crown-root fracture.

This case report describes the esthetic management of a dental trauma at the first visit and its subsequent treatments to restore the esthetics and function. Today, patients expect adequate esthetics and the ability to confidently smile immediately after the first appointment. In addition, they require that esthetics is maintained throughout the definitive treatment phase as well. After the use of the fractured crown as a temporary replacement crown, an orthodontic extrusion was undertaken to restore the physiological periodontal attachment. The tooth was then splinted for 6 months and at completion of this orthodontic stage, the permanent restoration was fabricated.

Analysis of mechanical preparations in extracted teeth using ProTaper rotary instruments: value of the safety quotient.

The purpose of this study was to apply the Endographe to analyze the vertical forces and torque developed during mechanical preparations in extracted teeth. The data collected in this study may be used to calculate the safety quotient (SQ) as proposed by J.T. McSpadden. The SQ formula is defined as the torque required to break a file at D3 divided by the mean working torque required to cut dentin. The Endographe is a unique force-analyzer device equipped to measure, record, and generate graphs of the vertical forces and torque exerted during root canal preparation. All preparations were performed by endodontists in roots with narrow, more restrictive canals, larger, more open canals, or in roots sectioned in two halves. All canals, including the sectioned canals, were prepared with ProTaper files in accordance with the manufacturer's guidelines for use. For narrow canals, the mean values of the generated vertical forces (g) and torque (g.cm) varied from 80 (+/- 20) g (SX) to 232 (+/- 60) g (F2) and from 80 (+/- 24) g x cm (F1) to 150 (+/- 45) g x cm (S2), respectively. For large canals, the mean values of the generated vertical forces (g) and torque (g x cm) varied from 80 (+/- 20) g (SX) to 340 (+/- 20) g (F1) and from 31 (+/- 9) g x cm (S2) to 96 (+/- 35) g x cm (SX), respectively. The SQ varied from 0.93 to 7.95 for narrow canals and from 1.58 to 14.50 for large canals. The SQ is intended to provide values that can be analyzed to predict whether a rotary file will have a tendency to break or will work safely during clinical use. However, if the formula is going to provide useful information, it must index the "rotation to failure torque" with the "mean working torque" at a specific location along the cutting blades of a file. Additionally, this mathematical formula does not account for factors such as the concentration of forces, the way the instruments are used, or the wear of the instruments. A precise protocol for canal preparation should emphasize using small flexible stainless steel hand files to create or verify that within any portion of a root canal there is sufficient space for rotary instruments to follow. When there is a confirmed smooth, reproducible glide path, then a "secured" space exists to safely guide the more flexible terminal extent of a rotary NiTi file. Endogrammes provide an innovative approach to the analysis of mechanical preparations and suggest that the ProTaper shaping files are best used with lateral forces to decrease the coronal screwing effect. The ProTaper finishing files should be used with slow penetration and be introduced only into canals that have a confirmed smooth and reproducible glide path. When any part of the overall length of a canal has been secured, then the number of instruments, the time spent utilizing each instrument, and the overall time progressing through a sequence of instruments to shape this region of the canal is reduced.

Radiographic evaluation of the prevalence and technical quality of root canal treatment in a French subpopulation.

AIM: This study was undertaken to examine the prevalence and technical quality of root fillings and the periapical status of endodontically treated teeth in a French subpopulation. METHODOLOGY: Full-mouth periapical radiographs were obtained from 208 consecutive adult patients seeking care within the dental service provided by the Hôtel-Dieu in Paris. The occurrence and technical quality of root fillings were assessed for each root according to the position and the density of the obturation. The periapical status was evaluated using the Periapical Index Scoring System. The type of coronal restoration and the presence of posts were also noted. RESULTS: Of the 8743 roots included in the survey, 23% were root-filled. An acceptable standard of treatment was found in 21% of roots with 16% of these cases associated with signs of periapical disease. In roots with unacceptable root-fillings, 27% had periapical pathology. A post was seen in 26% of the root-filled canals, with 29% of these cases associated with periapical pathology. An intracoronal restoration existed in 30% of the filled roots, of which 22% exhibited a periapical lesion. An extra-coronal restoration was present in 60% of the filled roots, of which 24% had radiographic signs of periapical pathology. The remaining 10% of filled roots that had no coronal restoration were associated with periapical pathology in 33% of cases. At least one periapical lesion was seen in 63% of the patients. CONCLUSION: The results demonstrate a high prevalence of root-filled teeth and poor technical quality of treatment. Roots presenting with acceptable root fillings were associated with a lower prevalence of periapical pathology (P < 0.001). Posts in roots were associated with periapical pathology significantly more than in roots without posts (P < 0.001).

Influence of rotational speed, torque and operator proficiency on failure of Greater Taper files.

AIM: The purpose of this study was to evaluate the influence of rotational speed. torque, and operator experience on the incidence of locking, deformation, and separation of instruments when using a specific Ni-Ti rotary instrumentation technique in extracted human teeth. METHODOLOGY: Greater Taper Ni-Ti rotary instruments (GT) were used in a crown-down technique. In one group (rotational speed evaluation) of canals (n = 300) speeds of 150, 2 50 and 350 r.p.m. (subgroups 1, 2 and 3) were used. Each one of the subgroups included 100 canals. In a second group (evaluation of torque) (n = 300) torque was set at 20, 30 and 55 Ncm (subgroups 4, 5 and 6). In the third group (evaluation of operator proficiency) (n = 300 three operators with varying experience (subgroups 7, 8 and 9) were also compared. Each subgroup included the use of 10 sets of GT rotary instruments and 100 canals of extracted human molars. Each set of instruments was used in up to 10 canals and sterilized before each case. NaOCl 2.5% was used as an irrigant. The number of locked, deformed, and separated instruments was recorded for each group. Statistical analysis was carried out with pairwise comparisons using Fisher's exact tests for each of the failure type. RESULTS: When the influence of rotational speed was evaluated, instrument deformation and separation did not occur in subgroups 1 (150) r.p.m.), 2 (250 r.p.m.), and 3 (350) r.p.m.). Instrument locking occurred in subgroup 3 only. Statistical analysis demonstrated a significant difference between the 150 and 350 r.p.m. groups and between the 250 and 350 r.p.m. groups with respect to instrument locking. In torque evaluation, neither separation, deformation nor locking occurred during the use of the instruments, at 150 r.p.m., and at the different torque values. When the operators were compared, although two instruments were separated in canals prepared by the least experienced operator. Fisher's exact tests did not demonstrate a significant difference between the three subgroups. Instrument locking, deformation, and separation did not occur with the most experienced operator. None of the instruments separated with the trained operator. CONCLUSIONS: Preclinical training in the use of the GT rotary instruments when used with a crown-down technique at 150 r.p.m. was crucial in avoiding instrument separation and reducing the incidence of instrument locking and deformation.

Analysis of the endogrammes developed during obturations on extracted teeth using system B.

The ability of an obturation technique to fill the root canal system tridimensionally depends partially on the timing and intensity of force applications. The aim of this study was to use the Endographe to analyze the forces and wedging effects developed in the root canal using a new obturation technique: System B. This system uses a heat plugger that simultaneously heats and pushes gutta-percha. The plugger was used to soften and move the gutta-percha apically during the down-pack stage. Two different methods, however, were used to withdraw the plugger from the compacted gutta-percha. One used the burst heat method, and the other was cold withdrawal. Five endodontists performed 50 obturations of prepared extracted teeth and 50 obturations of the "wedging effect" holder of the Endographe. The practitioner-obturation assignment was randomized. For each obturation the biggest plugger possible in relationship to the shape of the canal was chosen. For the obturation of the special holder the same tip was chosen. Endogrammes showed the force application and wedging effect sequences. The mean values for the vertical and horizontal forces and the wedging effect were, respectively, 16 +/- 2 N, 5 +/- 1 N, and 9 +/- 1 N. These results suggest that System B is one of the best techniques in terms of the developed vertical forces (low values) and the resulting wedging effect (high values) in relationship to the plasticity of the gutta-percha. The Endogrammes provide a new approach to the analysis of obturation techniques and a means to demonstrate correct and optimal manipulation of the new System B plugger.

Failure of ProFile instruments used with high and low torque motors.

AIM: The purpose of this study was to evaluate the failure incidence of ProFile nickel-titanium rotary instruments when used in conjunction with different motors and a specific instrumentation technique. METHODOLOGY: ProFile Ni-Ti rotary instruments (PRI) with 0.06 taper were used in a crown-down technique. In groups 1, 2 and 3, an air, a high torque and a low torque motor were used, respectively. Each group included 30 canals in extracted human molars. One set of PRI sizes 40-15 was used for each canal; they were sterilized before each case. A 2.5% NaOCl solution was used as an irrigant. The number of deformed and separated instruments was recorded for the various experimental groups. RESULTS: Instrument separation did not occur in any of the three groups. One and two instruments were deformed when using the air and high torque motors, respectively. CONCLUSIONS: The results indicated no difference between the three motors with respect to the incidence of instrument failure. The results suggest that the use of PRI in a crown-down manner with air control motors was safe.

Qualitative description of a new preparation technique: the balanced-force motion using the Endographe.

The forces and torque applied during the balanced-force motion technique of root canal preparation were measured with the Endographe. Five endodontists prepared 100 extracted teeth, all straight and with similar root anatomy. The assignment of "tooth practitioner" was randomized. Gates-Glidden burs were used to prepare the coronal part and ensure apical patency for the other instruments. The balanced-force technique with conventional instruments was then used for the body of the canal. For the apical part either the watch-winding pull with conventional instruments or the reversed balanced-force technique with manual GT files was used. The Endogrammes were similar among endodontists for the coronal phase and showed low vertical forces in contrast with the lateral forces. For the body the Endogrammes were highly specific and described perfectly the different steps of instrument work. For the apical part the Endogrammes of the conventional instruments showed a lack of vertical forces. The Endogrammes of the manual GT files showed that torque was applied inversely to that of the conventional instruments. Force application was similar. In conclusion these objective data indicate the correct way of working with the different techniques incorporated into the balanced-force motion technique.

Influence of rotational speed, torque and operator's proficiency on ProFile failures.

AIM: The purpose of this study was to evaluate the influence of rotational speed, torque, and operator experience with a specific Ni-Ti rotary instrumentation technique on the incidence of locking, deformation and separation of instruments. METHODOLOGY: ProFile Ni-Ti rotary instruments (PRI) sizes 40-15 with a 6% taper were used in a crown-down technique. In one group of canals (n = 300) speeds of 150, 250 and 350 rpm (subgroups 1, 2 and 3) were used. Each one of the subgroups included 100 canals. In a second group (n = 300) torque was set at 20, 30 and 55 Ncm (subgroups 4, 5 and 6). In the third group (n = 300) three operators with varying experience (subgroups 7, 8 and 9) were also compared. Each subgroup included the use of 10 sets of PRI and 100 canals of extracted human molars. Each set of PRI was used in up to 10 canals and then sterilized before each case. NaOCl 2.5% was used as an irrigant. The number of locked, deformed, and separated instruments for the different groups, and within each part of the study was analysed statistically for significance with chi-squared tests. RESULTS: In group 1 only one instrument was deformed in the 150-rpm group and no instruments separated or locked. In the 250-rpm group instrument separation did not occur, however, a high incidence of locking, deformation and separation was noted in the 350-rpm group. In general, instrument sizes 30-15 locked, deformed and separated. Chi-squared statistics showed a significant difference between the 150 and 350 rpm groups but no difference between the 150 and 250 rpm groups with regard to instrument separation. Overall, there was a trend toward a higher incidence of instrument deformation and separation in smaller instruments. Locking and separation occurred during the final passage of the instruments, in the last (tenth) canal in each subgroup. In the second group, neither separation nor deformation and locking occurred during the use of the ProFile instruments, at 150 rpm, and at the different torque values. In the third group, chi-squared analysis demonstrated that significantly more instruments separated with the least experienced operator. Instrument locking, deformation, and separation did not occur with the most experienced operator. CONCLUSIONS: Preclinical training in the use of the PRI technique with crown-down at 150 rpm were crucial in avoiding instrument separation and reducing the incidence of instrument locking and deformation.

Cyclic fatigue of ProFile rotary instruments after clinical use.

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 90 degrees 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.

Analysis of forces developed during mechanical preparation of extracted teeth using Profile NiTi rotary instruments.

AIM: The aim of this study was to analyse the vertical forces and torque developed in the root canal system of extracted teeth during mechanical preparation using ProFile NiTi instruments. METHODOLOGY: Instrument wear and fracture is in great part due to the repeated application of forces and torque during the course of root-canal preparation but research into the direct relationship has been hampered by the lack of adequate measuring devices. Measurements of these forces and torque were made with a new force analyser device, the Endographe, that was equipped with a holder to record and generate graphs of the vertical forces and torque exerted during the preparations. These preparations was performed by endodontists or students either with a series of instruments of increasing size or with the crown-down pressureless technique. RESULTS: The mean values for the endodontists of the generated vertical forces and torque varied, respectively, from 4 to 6N and from 7.105 to 12.105 Nm for the step-back technique and from 2.9 to 4.2 N and from 18.105 to 20.105 Nm for the crown-down technique. This suggested that the crown-down technique generated lower stresses (lower torque and lower vertical forces), although these findings also depend on the shape of individual canals. The students initially showed wide variations in generated forces, with significantly lower vertical force the torque values. By the end of the experimental sessions their values were similar to those of the endodontists, which indicated improvement in the efficiency of manipulation. CONCLUSIONS: Further work is needed to investigate the relationship between the force and the torque data from this study and the incidence of instrument fracture with the two techniques, as the clinical implications are considerable. It must be noted, however, that the Endographe is unable to take into account the cutting efficiency of the instruments. The use of graphs provides a new approach to the analysis of mechanical preparation.

Location of contact areas on rotary Profile instruments in relationship to the forces developed during mechanical preparation on extracted teeth.

AIM: The aim of this study was to locate the areas of direct instrument contact with dentine in the root canal system during rotary preparation and to analyse the relationship between these areas and the vertical forces and torque developed during the preparation. METHODOLOGY: Canal preparations were performed by endodontists either with the step-back (SB) or the crown-down (CD) technique. In order to locate the areas of contact, the instruments were coated with two layers of gold by electro-deposition. They were photographed before and after use, and a coding system, based on mm from the instrument tip, was devised to designate areas of gold removal or instrument wear due to friction. To standarise the conditions of instrument manipulation, the teeth were fixed in the Endographe holder, and this device was used to measure vertical forces and torque. RESULTS: The results showed that the first series of instruments used for the CD technique (taper 0.06) left 2 +/- 1 mm of the tip with the gold intact, indicating that these instruments and this step of the CD technique are the safest part of the preparation. For all other instruments (taper 0.04 series), the areas of gold removal involved the 3 mm around the tip and this finding was independent of the order of instrument use and preparation technique (SB or CD). The differences between the two techniques were significant in terms of the mean area of decolouration and the mean force and torque values. For the SB and CD techniques, the contact areas were, respectively, 10 +/- 3 and 7 +/- 2 mm. The forces and torque values were correspondingly higher for SB vs. CD; the mean values were, respectively, 19 and 21 N for vertical forces and 16 10(5) and 13 10(5) Nm for torque. CONCLUSIONS: The recorded torque values and the location on the instruments of the areas of contact with dentine during this development of torque i.e. at or near the tip, indicate that great caution should be used with the rotary technique, particularly with the taper 0.04 instruments, regardless of preparation technique.

Cyclic fatigue of Profile rotary instruments after simulated clinical use.

AIM: The purpose of this study was to evaluate cyclic fatigue of Profile Ni-Ti rotary instruments (PRIs) after dry heat sterilization and up to 10 times simulated clinical use. METHODOLOGY: Instruments of size 40-15 were used in a crown-down technique. Three groups were included in this study. In groups 1 and 2, each set of instruments was used in five and 10 canals, respectively. Group 3 was the control group. NaOCl at a concentration of 2.5% was used as an irrigant. Each set of instruments was sterilized before each use. RESULTS: The PRI size 40 demonstrated the lowest incidence of rotations to breakage. One-way analysis of variance and Turkey's HSD test showed statistically significant differences among different file sizes within each group. CONCLUSIONS: The results showed that dry heat sterilization and simulated clinical use in the presence of NaOCl did not lead to a decrease in the number of rotations to breakage of the files.

Analysis of forces developed during obturations. Wedging effect: Part I.

The aim of this study was to define the "wedging effect" created by the intracanal forces developed during obturations and to measure it using a force analyzer device. In endodontics, the wedging effect is the result of, for example, a plugger pushing gutta-percha into a canal: the plugger functions much as the rod of a hydraulic jack and the vertical force applied by this rod induces in the cylinder (i.e. the canal) a hydrostatic pressure that is relatively equal in all directions. It is these forces resulting from the hydrostatic pressure that have been labeled the wedging effect. The original device, the Endographe, had a monobloc cupule for measuring the external vertical and horizontal forces developed by a practitioner, but it was unable to measure the intracanal forces. With a new cupule composed of two independent parts joined under pressure, the wedging effect was recorded and analyzed. Two obturation methods, warm vertical compaction and lateral condensation, were performed by endodontists. The forces were depicted by Endogrammes as a function of time. For all of the forces developed during the two techniques, the mean values showed a nonsignificant difference between the different practitioners. The use of graphs provides a new approach to the analysis of intracanal forces as they develop our time and permits the comparison of different obturation techniques.

Analysis of forces developed during obturations. Wedging effect: Part II.

The aim of this study was to use a force analyzer device, the modified Endographe with a new cupule, to compare the forces and wedging effects developed in the root canal using four obturation techniques: warm vertical compaction, lateral condensation, thermomechanical compaction, and Thermafil condensation. The different methods--that varied in instrumentation, duration, and compaction load--were studied from graphs representing the force application sequences. In addition, the graphs resulting from modifications in technique (such as using an undersized spreader and pluggers that were either too small or too big) and deliberately induced failures in technique (by use of a too small condenser or a too small master cone) were studied. The mean values for the wedging effect for warm vertical compaction, lateral condensation, thermomechanical compaction, and Thermafil condensation were, respectively, 0.65 +/- 0.07 kg, 0.8 +/- 0.1 kg, 0.6 +/- 0.08 kg, and 0.03 +/- 0.01 kg. The use of graphs provides a new approach to the analysis of obturation techniques.