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PubMed2006

Residual dentin thickness in bifurcated maxillary premolars after root canal and dowel space preparation.

Residual dentin thickness in 25 extracted bifurcated maxillary premolars after canal and Parapost preparation was assessed using acrylic muffle, after embedding in polyester resin and sectioned horizontally. After each procedure, the residual dentin thickness was compared to the original dentin thickness at eight aspects in three root levels. Residual dentin thickness measurements were calculated using photographs and a Digitizer. In the lingual aspect, the original dentin thickness averaged 0.99 mm (coronal slice) and 0.78 mm (middle slice). Dentin removal after dowel preparation was 31%. Three-way ANOVA with repeated measures was used. The difference in residual dentin thickness was highly significant regarding procedure (canal and dowel preparation, p < 0.0001), slice (middle, coronal, p < 0.0001), and the eight aspects (p < 0.0001). This in vitro study emphasizes the minimal dentin width of the buccal root, especially towards the bifurcation. Thus, dowels should be avoided in this root.

Analysis of Variance↗
PubMed2006

The radix entomolaris and paramolaris: clinical approach in endodontics.

Mandibular molars can have an additional root located lingually (the radix entomolaris) or buccally (the radix paramolaris). If present, an awareness and understanding of this unusual root and its root canal morphology can contribute to the successful outcome of root canal treatment. This report discusses endodontic treatment of three mandibular molars with a radix entomolaris or paramolaris, both of which are rare macrostructures in the Caucasian population. The prevalence, the external morphological variations and internal anatomy of the radix entomolaris and paramolaris are described. Avoiding procedural errors during endodontic therapy demand an adapted clinical approach to diagnosis and root canal treatment.

Adult↗
PubMed2005

The risk of furcal perforation in mandibular molars using Gates-Glidden drills with anticurvature pressure.

OBJECTIVE: The aim of this study was to determine whether using Gates-Glidden (GG) drills and anticurvature pressure in curved mesial root canals of mandibular molars could remove more dentin from the mesial canal wall and remove less dentin from the distal canal wall at a level 2 mm below the furcation. STUDY DESIGN: In 5 groups of mesial roots with an average curvature of 32-34 degrees, 103 canals were prepared using a size #2 or #3 GG drill in the coronal third (straight portion of the canal only) or coronal half (straight portion and part of the curved portion), with or without applying anticurvature pressure. Using a modification of the Bramante muffle mold the cross-section of the mesial root at 2 mm below bifurcation was photographed twice, before and after the use of GG; the photos were then scanned as tagged image files. The thickness of the mesial and distal canal walls wer measured using an image analysis program. The reduction of the wall thickness after the use of GG was calculated. RESULTS: Before enlargement, the average and minimal thickness of the distal wall was 0.92 and 0.43 mm respectively, thinner than that of the mesial wall (1.50 and 0.87 mm, correspondingly). After the use of GG, the reduction of the mesial wall was similar to the reduction of the distal wall (P > .05 for all groups). In 4 groups the maximal reduction of the distal wall was > or =0.72 mm. CONCLUSIONS: After using GG drills and anticurvature pressure, dentin was uniformly removed regardless of the size of the GG and the depth of placement of GG. Flaring with GG drills in mandibular molars may result in perforations; application of anticurvature pressure did not reduce the risk.

Dental Instruments↗
PubMed1991

Vertical root fracture and relative deformation during obturation and post cementation.

There are several speculated etiologies of vertical root fractures such as pressure exerted during post placement and excessive forces during lateral condensation. However, there are no reports comparing these two forces by use of the same measurement system. This study determined and compared on single-rooted teeth (1) the amount of strain to the root that occurs during obturation and post cementation and (2) the incidence of incomplete and complete vertical root fractures occurring during the aforementioned procedures. Canals of 32 extracted maxillary central incisors were step-back prepared. Teeth were randomly divided into negative and positive controls and experimental groups. The amount of root distortion was recorded with a strain gauge during each of the following procedures: (1) lateral condensation, and (2) lateral condensation plus cementation of a cast gold post. Relative deformations were compared statistically. Teeth were examined by transillumination and stereomicroscopy for incomplete and complete fractures and compared among groups. Data showed significantly more relative deformation with placement of a post and loading than with obturation alone. The accumulation of strain from both procedures did not significantly increase incidence of vertical root fractures. The results indicate that stresses from cementation of posts is more likely to cause relative deformation of roots.

Cementation↗
PubMed1987

Odontic trisection: an alternative therapy.

The purpose of this article is to familiarize dentists with alternative methods of therapy for trifurcation involvement. Because failures with complex treatment are a reality, patients should be informed of the risks before treatment is instituted. Despite the potential for failure, longitudinal clinical results support the extraordinary measures to retain teeth in critical arch positions.

Crowns↗
PubMed1989

Effect of metal collars on resistance of endodontically treated teeth to root fracture.

Fractures of restored pulpless teeth without reinforcement are a familiar dilemma to the dentist. This study examined the effect of a metal collar with approximate 3 degrees of taper on the resistance of endodontically treated roots to fracture. Teeth without copings failed at a load of 49.6 kg whereas teeth with metal collars failed at a load of 65.29 kg. Our findings indicated that reinforcement with a metal collar is necessary to enhance resistance to root fracture.

Crowns↗
PubMed1998

A retrospective study of 236 patients with teeth restored by carbon fiber-reinforced epoxy resin posts.

STATEMENT OF PROBLEM: The Composipost dowel is made of stretched, aligned carbon fibres embedded in an epoxy-resin matrix. It is widely used in Europe and Canada for the restoration of endodontically treated teeth and was introduced in the United States 2 years ago as the C-Post dowel. PURPOSE: This retrospective study evaluated treatment outcome of the Composipost system after 2 to 3 years. MATERIAL AND METHODS: A total of 236 patients treated during a 1-year period by seven Swedish dental practitioners were included. Of those, 146 patients consented and data were collected from the dental records of the remaining patients. Thus, the material comprised 236 teeth restored with carbon fiber-reinforced epoxy resin post, 130 maxillary and 106 mandibular teeth, with a mean restoration time of 32 months (range 27 to 41). Periodontal conditions, radiographic signs, and prosthodontic results were recorded. RESULTS: Five teeth (2%) had been extracted for reasons unrelated to the Composipost system. Periodontal conditions such as plaque accumulation, gingival health, bleeding on probing, and pocket depth around the teeth with Composipost dowels were similar to the control teeth. No dislodgment or root or post fractures were observed clinically or on radiographs. Radiographic examination of bone height measured from the apex to the bone margin mesially and distally showed differences on the mesial side but not on the distal surface (p < 0.05) between the Composipost-treated teeth and the controls. CONCLUSIONS: Promising results after 2 to 3 years of clinical service indicate that this system can be a viable alternative to conventional post-and-core systems.

Adult↗
PubMed1994

An in vitro comparison of incomplete root fractures associated with three obturation techniques.

This study compared the incidence of incomplete root fractures among five groups of mandibular incisors (20/group). The groups were: (a) no canal preparation, (b) canal preparation, (c) canal preparation and obturation with laterally condensed gutta-percha, (d) canal preparation and obturation with thermoplasticized gutta-percha on a central carrier (Thermafil), and (e) canal preparation and obturation with thermoplasticized injectable gutta-percha (Ultrafil). Following experimental manipulation, all teeth were stained, transversely sectioned, and evaluated for the presence of root fracture. No complete root fractures were noted. The lowest incidence of stained incomplete fracture was found in the no canal preparation group. The canal preparation, lateral condensation, Ultrafil, and Thermafil groups had more incomplete fractures than the no canal preparation group. The incidence of stained fracture in the three obturation groups was not significantly different from the incidence in the group which had only canal preparation.

Humans↗
PubMed1994

An in vivo comparative study of two apex locators.

Two different electronic apex locators were used before extraction to determine working length in 116 root canals belonging to 34 molars. The results were then compared with postextraction working length measurements. The determinations were made before and after eliminating the canal contents and drying the interior. The results showed that 84.8% and 79.3% of the Odometer, and 89.6% and 88.7% of the Endocater readings for dry and nondry canals, respectively, occurred within the two 0.5-mm intervals closest to the apical constriction.

Dental Pulp Cavity↗
PubMed1994

Radiographic determination of canal length direct digital radiography versus conventional radiography.

This research compared the length determination images produced by Trophy and Regam direct digital radiographic systems with conventional E-speed radiographs. Size #15 K files were placed in the canals of 19 teeth of cadaver specimens and radiographed in a geometrically standardized bench device. Three evaluators estimated the length adjustment necessary to position the file at the apex. The mean estimated adjustment lengths were compared with the true, anatomically determined adjustment lengths. Statistical analysis with analysis of variance and the Student-Newman-Keuls test indicated no significant difference between direct digital thermal print images and conventional radiographs (p > 0.10). Length adjustment estimates with conventional radiographs were significantly more accurate than Regam high-resolution computer monitor images (p < 0.01). Additionally, it was determined that length adjustment estimates were significantly more accurate when the file was placed short of the apex (p < 0.001). The clinical relevance of these differences is discussed.

Analysis of Variance↗
PubMed1996

An in vivo comparison of gradient and absolute impedance electronic apex locators.

Two electronic apex locators based on the gradient (Apit) and absolute (Odontometer) impedance principles were evaluated. Distances of file tips to apical foramina were determined in vivo with the electronic apex locators and subsequently verified after extraction. Mean differences between file tips and apical foramina were +0.14 +/- 0.27 mm and -0.36 +/- 0.71 mm for the Apit and Odontometer, respectively. These differences were statistically significant (p < 0.001). the Apit's and Odontometer's results ranged from +0.85 to -0.65 mm and from +0.35 to 2.45 mm from the apical foramen, respectively. Ninety-three and 73% of the findings for the Apit and the Odontometer, respectively, were within the +/- 0.5 mm range, whereas 100% and 86%, respectively, were within the +/- 1.0 mm range. Thirty-three and 43% of the results for the Apit and the Odontometer, respectively, were 1.0 mm or less coronal to the apical foramen. The Apit tended to yield the more reliable results because of the narrower range.

Adult↗
PubMed1995

Effect of dentin preparation and acid etching on the sealing ability of glass ionomer and composite resin when used to repair furcation perforations over plaster of Paris barriers.

Access openings and furcation perforations were prepared in 60 human extracted teeth and randomly divided into four equal groups. Plaster of Paris barriers were created in all perforations. The defects were obturated using either glass ionomer or composite resin with or without acid etching of the dentin. The pulp chambers and access openings were filled with composite resin. After immersion in 2% methylene blue solution for 2 weeks, the teeth were sectioned longitudinally and dye penetration was measured under a stereomicroscope using the NIH Image 1.47 Macintosh program. The results indicated that light-cured glass ionomer provided a significantly better seal than did the light-cured composite resin with or without dentin preparation and acid etching. The glass ionomer allowed significantly less dye penetration when used on etched dentin than it did on nonetched dentin.

Acid Etching, Dental↗
PubMed1992

Master cone apical behavior under in vitro compaction.

This study first evaluated the fitting of two brands of gutta-percha points 0.5 and 1.0 mm short of the apical end of an artificial canal. Photographs were taken before and after vertical or lateral compaction and measurements were made. Warm gutta-percha compaction was associated with greater apical cone movement than lateral condensation. Total apical cone movement was not related to the distance the master cone was initially adapted from the apical opening.

Analysis of Variance↗