Root-treated Teeth Research Articles

Differential aggressiveness of ethylenediamine tetraacetic acid in causing canal wall erosion in the presence of sodium hypochlorite

Objective This study tested the hypothesis that the use of ethylenediamine tetraacetic acid (EDTA) as a final irrigant causes canal wall erosion only after prolonged use of 5.25% sodium hypochlorite (NaOCl) as the initial irrigant. Methods Two irrigation protocols were employed: (1) 5.25% NaOCl as the initial irrigant for 10 min and 17% EDTA as the final irrigant for 2 min; and (2) 5.25% NaOCl for 60 min and 17% EDTA for 2 min. Flexural strengths of dentine beams prepared from human mid-coronal dentine were evaluated using a miniature three-point bending device after they were irrigated with either protocol. Transmission electron microscopy was used to examine the conditions of instrumented canal walls irrigated with either protocol after they were bonded with methacrylate resin-based sealers. Results Immersion of dentine beams in NaOCl for 60 min instead of 10 min prior to the use of EDTA resulted in a significant ( p < 0.001) decline in flexural strength. For both NaOCl initial rinsing times, a 2-min final irrigation with EDTA created similar 0.5 μm thick demineralisation fronts. However, extensive surface and subsurface erosion of radicular dentine was seen only when the dentine was immersed in NaOCl for 60 min. Conclusion The apparent aggressiveness of EDTA in causing canal wall erosion is attributed to the prolonged use of NaOCl. The associated decline in dentine flexural strength has potential clinical relevance when thin pulp chamber dentine is immersed in NaOCl for lengthy periods during canal instrumentation. This may render root-treated teeth more prone to vertical fracture.

Long-term survival of complete crowns, fixed dental prostheses and cantilever fixed dental prostheses with posts and cores on root-treated teeth

Restricted accessAbstractFirst published October 1, 2007Long-term survival of complete crowns, fixed dental prostheses and cantilever fixed dental prostheses with posts and cores on root-treated teethBacker H De, Maele G Van, […], V Decock, and Berghe L Van den, +1 -1Volume os14, Issue 4https://doi.org/10.1308/135576107782144298

Assessment of the amount of remaining coronal dentine in root-treated teeth

There is currently no standardised technique to measure the amount of coronal dentine remaining in a root-treated tooth after crown preparation. The aim of this study was to develop a method of measuring remaining coronal dentine in root-treated teeth and to propose an index for grading tooth restorability. The study recruited 20 patients who had completed molar endodontic treatment at the Eastman Dental Hospital and had been prescribed an amalgam coronal-radicular core with a full coverage cast restoration. Using a series of interlocking special trays and impressions, a method was devised to produce a cast of the amount of remaining dentine coronal to the finish line after crown preparation. This cast was scanned using a laser profilometer and the volume of remaining dentine was calculated. A tooth restorability index (TRI) was developed to assess the strategic value of the remaining dentine. The TRI allowed scores of 0-3 in each sextant with a maximum score of 18 per tooth. Twenty teeth were scored by three examiners and the TRI scores varied from 2 to 13. The volume of coronal dentine varied from 61.73 to 232.22 mm(3). A tooth restorability index has been devised to assess the strategic value of remaining dentine. A Kappa statistic was calculated to produce values of 0.584, 0.688 and 0.720, giving moderate-good agreement between the examiners.

Crowns and extra-coronal restorations: Endodontic considerations: the pulp, the root-treated tooth and the crown

Crowns and extra-coronal restorations: Endodontic considerations is the fourth in the series on crowns and other extra-coronal restorations. This article focuses strongly on contemporary biological principles, and is not intended to provide a comprehensive review of commercially available materials and techniques. Principles are illustrated in a variety of clinical case scenarios.

Crowns and extra-coronal restorations: Endodontic considerations: the pulp, the root-treated tooth and the crown

Endodontic considerations is the fourth in the series on crowns and other extra-coronal restorations. This article focuses strongly on contemporary biological principles, and is not intended to provide a comprehensive review of commercially available materials and techniques. Principles are illustrated in a variety of clinical case scenarios.

An in vitro study to compare impact fracture resistance of intact root‐treated teeth

The aim of this in vitro study was to determine the effect on impact fracture resistance of three methods for restoration of root-treated lower incisor teeth with otherwise intact natural crowns. In a control group (Group I) laterally condensed gutta-percha filled the entire root canal, whereas part of the root filling was removed to enable insertion of a 1 mm diameter post in the other two groups. Stainless steel posts were placed in Group II and experimental carbon fibre reinforced carbon (CFRC) in Group III. A composite resin luting agent was used to lute the posts, and standardized composite resin restorations were placed in each access cavity. Fifteen specimens of each group were tested to failure with a single impact force applied at 90 degrees to the mid-point inciso-cervically on the labial surface. The peak force, peak energy, and first peak total energy required to fracture each specimen were recorded. The results showed no significant difference between the three groups, nor was a difference in the mode or site of fracture observed. The results suggested that there is no advantage from the point of view of fracture mechanics in 'restoring' intact root-treated teeth with either stainless steel or carbon fibre reinforced carbon rods.

Tooth transplantation with the periodontium intact: A histometric analysis

A method was devised, from a pilot study, for transplanting a root-treated tooth with an intact periodontium into a newly prepared socket to assess whether the prognosis for transplantation procedures could be improved. Five male vervet monkeys were used for the definitive study. The mandibular central incisors were extracted from each monkey and the sockets were allowed to heal for 5 weeks. Thereafter a window of gingiva overlying each of these healed receptor sites was removed and the sockets were prepared with tapered burs. The distal root of the mandibular second molar was used as the transplant tooth and the distal root of the first molar as the control tooth. The transplant tooth was removed, together with surrounding alveolar bone which was then trimmed to a thickness of approximately 1 mm. The control tooth was extracted with root forceps. After transplantation, the teeth were splinted to the adjacent incisors for 3 weeks. After 8 weeks the healing process was examined histologically, both qualitatively and quantitatively. Replacement resorption (ankylosis) was not observed. Student's t test for paired samples revealed that the incidence of secondary cementum formation was significantly greater on the control teeth. The minimization of trauma may be the reason ankylosis did not occur.

Magnetic retention for complete and partial overdentures. Part I

Magnets have been used as aids to denture retention for many years with some success. The development of new cobalt and rare earth magnet alloys has greatly extended the potential application of magnetic retention in removable partial dentures, complete overdentures, fixed partial dentures, and sectional dentures. Effects of magnetic fields on tissues have been investigated extensively, with conflicting results, but reports describing dental applications for magnets claim no damaging tissue effects. The closed-field magnetic retention system described avoids any possibility of magnetic field effects on tissues by using paired magnets and a fixed and detachable keeper in a modified horseshoe arrangement. The detachable keeper is cemented or screwed to a decoronated, root-treated tooth. The denture-retention element, consisting of paired magnets and a fixed keeper, abuts the keeper in the tooth root and holds the denture in place by magnetic attraction. When in position, there is no external field surrounding the denture or tooth root. This arrangement also doubles the available retention. The shape, size, and configuration of the two magnets and fixed and removable keepers were chosen to provide maximum retention in a magnetic denture retention unit of a size convenient for most applications. The retention provided is approximately 300 gm per unit. The magnet alloy, Co 5Sm, is very hard but brittle, and it can corrode in the mouth. To prevent this from occurring in service, end plates protect the exposed magnet faces. The plates, of the same stainless steel alloy as the keepers, prevent magnet corrosion and reduce wear at the denture-retention keeper-element interface in service.