Roentgenographic Investigation of Frequency and Degree of Canal Curvatures in Human Permanent Teeth

doi:10.1097/00004770-200203000-00017

Journal of Endodontics

Volume 28, Issue 3, March 2002, Pages 211-216

https://doi.org/10.1097/00004770-200203000-00017 Get rights and content

Canal curvatures of 700 permanent human teeth were determined by measuring the angle and the radius of the curvatures and the length of the curved part of the canal. For each type of tooth (except third molars) 50 were selected at random and were investigated. Size 08 silver points were inserted into the canals, and the teeth were radiographed from a facial and proximal view by using a standardized technique. All radiographs were analyzed by a computerized digital image processing system. Of the 1163 root canals examined, 980 (84%) were curved and 65% showed an angle ≤ 27 degrees with radii < 40 mm. Thirteen percent displayed angles between 27 degrees and 35 degrees with radii not greater than 15 mm, and 9% of all canals that were investigated had curves > 35 degrees with the greatest radius of 13 mm. The greatest angle of all the teeth was 75 degrees with a radius of 2 mm. To define the canal curvature mathematically and unambiguously, the angle, the radius, and the length of the curve should be given.

Section snippets

MATERIALS AND METHODS

In 10 private practices, all extracted human permanent teeth were collected and sorted according to tooth type. Each tooth was categorized as one of 14 types: maxillary central incisors, maxillary lateral incisors, maxillary canines, maxillary first premolars, maxillary second premolars, maxillary first molars, maxillary second molars, and the same groups were used to categorize the mandibular teeth. In each group, 50 teeth were selected randomly for the investigation. Thus, a total of 700

RESULTS

Of the 1163 root canals examined, 97.4% were patent to a size 08 silver point to the apical foramen and 980 (84%) were curved (Table 1). In total, 204 (17.5%) canals exhibited a secondary curvature and were, therefore, classified as S-shaped root canals. In maxillary teeth, 12.3% of all canals that were investigated were S-shaped, and 23.3% in mandibular teeth were S-shaped.

b = buccal canal; p = palatal canal; s = singular root canal; mb = mesio-buccal canal; mb2 = second mesio-buccal canal; db

DISCUSSION

Successful root canal instrumentation requires considerable knowledge of canal curvature. Because the result of debridement is affected significantly by the radius of curvature (¹⁵) and nearly all types of teeth showed curvatures in the unseen PV, the purpose of this study was to describe the degree of root canal curvatures by measuring an arbitrary angle, according to Schneider (¹⁰), and the radius and length of the curved portion by using a computerized digital image processing program.

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Twenty-four flattened distal root canals of mandibular molars with a buccolingual diameter 4 or more times larger than the mesiodistal diameter were prepared with Reciproc Blue (RB) R40 (VDW GmbH, Munich, Germany) and filled using the Tagger hybrid technique. All canals were retreated with RB R40, and apical enlargement was performed with RB R50 (VDW GmbH). The specimens were randomly distributed into 2 groups: XPFR or Flatsonic (n = 12). The percentage of remaining filling material after retreatment and centralization ability was evaluated. Data were submitted to Mann-Whitney, Wilcoxon, and unpaired t tests (α = 5%).
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Comparison of Curvature Severity Between Sagittal and Coronal Planes of Mesiobuccal Canals in Permanent Maxillary First Molars Using Multiple Complexity-risk Criteria: A CBCT Cross-sectional Study of a Brazilian Subpopulation
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This study aimed to compare the curvature severity of mesio-buccal (MB) canals between sagittal and coronal planes using cone-beam computed tomography.
In a Brazilian subpopulation, untreated MB1 (n = 141) and MB2 (n = 72) with single curvatures in sagittal and coronal planes were measured to determine their angle and radius (r), plus the prevalence of S-shaped canals was recorded. Curvature severity was defined according to the American Association of Endodontists Case Difficulty Assessment form (AAE) and EndoApp (EA), as well as their modified versions that consider angle and radii (AAE-r, EA-r). Data were converted into mean angle and r, percentage of canals >30°, AAE, EA, AAE-r and EA-r categories. The influence of r on case severity was assessed. Statistical analysis was performed using t-tests and chi-squared tests. The level of significance was set as P ≤ .05.
For single curvatures, significantly higher mean degrees (SD) angles were found in the sagittal views in both canals (MB1 sagittal: 35 [11]; MB1 coronal: 13 [13]; MB2 sagittal: 29 [14]; MB2 coronal: 22 [15] [P < .05]). A greater percentage of angles >30° (MB1: 56.7% vs 6.4%; MB2: 44.4% vs 22.2%) in sagittal planes compared to coronal planes was also found. Conversely, a higher prevalence of S-shaped canals (MB1: 33.3% vs 7.1% MB2: 31.9% vs 15.3%) was observed in coronal planes. Significant differences between AAE and AAE-r were present with greater case severity when radii were considered (P < .05).
Sagittal planes were associated with more severe single curvatures, while coronal planes had a greater prevalence of S-shaped canals.
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LAI (89.3% ± 5.9%) showed the greatest hydrogel removal followed by SAI-E (65.5% ± 3.3%) and ultrasonically-activated irrigation (59.1% ± 4.7%), with significant differences between these groups (P < .05). Needle irrigation, MA, and sonically-activated irrigation EndoActivator performed equally (P > .05) and obtained the significantly lowest values (P < .05). LAI and SAI-E showed the significantly best hydrogel removal from the main canal (P < .05). At all three levels, LAI removed significantly more hydrogel from the lateral canals than all other techniques (P < .05).
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Citation Excerpt :
The canal curvature was measured according to the Schneider method and recorded as α (Fig. 2).15 The radius of curvature (r) was calculated according to the formula suggested by Schäfer.16 In brief, if the length of the chord between the beginning of the curve and the apical foramen was measured as S (Fig. 2), then r = S/2sinα.
Glide path management (GPM) is a consequential clinical step that serves to influence predictably successful root canal therapy. However, the effect of GPM on the shaping ability of single-file system remains controversial. This study compared the performance of rotary single-file One Curve (OC) and reciprocating single-file Reciproc Blue (RCB) in combination with/without different glide path techniques: no glide path preparation (NG), PathFile (PF), ProGlider (PG) and WaveOne Gold Glider (WOGG), respectively.
80 simulated curved canals (n = 10 canals/per group) were instrumented to an apical size of 0.25 mm using OC and RCB in combination with/without different glide path techniques, respectively. The amount of resin removal, canal transportation, and the degree of canal straightening were measured in Photoshop CS6 software. Statistical analysis of the data was performed by using Kruskal–Wallis test, followed by Dunn's post hoc test with Bonferroni correction (α = 0.05).
Post–glide path analysis found that WOGG and PG produced less canal transportation and curvature straightening than PF (P < 0.05). Post-shaping analysis showed that OC groups removed significantly less resin than RCB groups (P < 0.05). The PG and WOGG subgroups in both OC groups and RCB groups produced less transportation and curvature straightening than NG and PF subgroups (P < 0.05). OC + PG subgroup and OC + WOGG subgroup yielded the least canal transportation and curvature straightening (P < 0.05).
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CLINICAL ARTICLESRoentgenographic Investigation of Frequency and Degree of Canal Curvatures in Human Permanent Teeth

Section snippets

MATERIALS AND METHODS

RESULTS

DISCUSSION

J Endodon

J Endodon

J Endodon

J Endodon

Oral Surg Oral Med Oral Pathol

J Endodon

Oral Surg Oral Med Oral Pathol

Oral Surg Oral Med Oral Pathol

CLINICAL ARTICLES
Roentgenographic Investigation of Frequency and Degree of Canal Curvatures in Human Permanent Teeth