001. Guzy GE, Nicholls JI. In vitro comparison of intact endodontically treated teeth with and without endo-post reinforcement. J Prosthet Dent 42:39-44, 1979.
002. Kane, J., et al. Fracture Resistance of Amalgam Coronal-Radicular Restorations. J Prosthet Dent Vol 63, 607-13, 1990.
003. Abrams, L. and Trachtenberg, D.I. Hemi-section: Technique and restoration. DCNA 18:415-44, 1974.
004. Zmener O. Effect of dowel preparation on the apical seal of endodontically treated teeth. J Endodon 6:687, 1980.
005. Goerig, A.C. and Mueninghoff, L.A. Management of the endodontically treated tooth. Part I: Concept for restorative designs. J Prosthet Dent 49:340-345. 1983. Part II: Technique. J Prosthet Dent 49:491-497, 1983.
006. Deutsch, A.S., et al. Prefabricated dowels: A literature review. J Prosthet Dent 49:498-503, 1983.
007. Chan, R., and Bryant, R. Post-Core Foundations for Endodontically Treated Posterior Teeth. J Prosthet Dent Vol 48, 401-06, 1982.
008. Miller, A.W. Post and core systems: Which one is best? J Prosthet Dent 48:27-38, 1982.
009. Larson, T.D. and Jensen, J.R. Microleakage of composite resin and amalgam core material under complete cast crowns. J Prosthet Dent 44:40-44, 1980.
010. Abou-Rass, M. Evaluation and clinical management of previous endodontic therapy. J Prosthet Dent 47:528-534, 1982.
011. Abou-Rass, M. The stressed pulp condition: An endodontic-restorative diagnostic concept. J Prosthet Dent 48:264-267, 1982.
012. Millstein, P.L., Yu H, Hsu, C.S. and Nathanson, D. Effects of cementing on retention of a prefabricated screw post. J Prosthet Dent 57:171-174,1987.
013. Liberman, R. et al. Restoration of posterior pulpless teeth: Amalgam onlay vs. cast gold onlay restoration. J Prosthet Dent 57:540-543, 1987.
014. Camp, L.R and Todd, M.J. The effect of dowel preparation on the apical seal of three common obturation techniques. J Prosthet Dent 50:664-666, 1983.
015. Kurer, H., Combe, E.C. and Grant, A.A. Factors influencing the retention of dowels. J Prosthet Dent 38:507, 1977.
016. Lovadhal, P.E. and Nicholls, J.I. Pin-retained amalgam cores versus cast-gold dowel cores. J Prosthet Dent 38:507, 1977.
017. Plasmans P J, et al. In vitro comparison of dowel and core techniques for endodontically treated molars. J Endon 12:382-387, 1986.
018. Kastenbaum F. The restoration of the sectional molar. Int J Periodontics and Restorative Dent 6:9-23, 1986.
Handout not available at this time........
45-001. Guzy, G.E. and Nicholls, J.I. In vitro comparison of intact endodontically treated teeth with and without endo-post reinforcement. J Prosthet Dent 42:39-44, 1979.
Purpose: To compare, in vitro, the breaking loads of endodontically treated teeth, with and without cemented posts, to determine if the post reinforces the root against fracture.
Materials & Methods: Fifty-nine extracted incisor and cuspid teeth were prepared for root canals and posts. Access preparations simulated those of teeth with large pulp chambers. Half of the teeth were merely restored with silicate cement. The other half had Kerr Endo-Posts (size 100) cemented with zinc phosphate cement. The teeth were stressed to failure on an Instron testing machine with forces applied at 130 degrees to the long axis of the tooth.
Conclusion: No statistically significant reinforcement was demonstrated by cementing a Kerr Endo-Post #100 into a sound endodontically treated tooth.
45-002. Kane, J., et al. Fracture Resistance of Amalgam Coronal-Radicular Restorations. J Prosthet Dent Vol 63, 607-13, 1990.
Purpose: To determine the effect that pulp chamber height and extension of coronal-radicular amalgam restorations into the root canal space have on fracture resistance of endodontically treated teeth.
Materials & Methods: Six groups of 10 mandibular molars were mounted in acrylic resin, and crowns were ground apically until the wall height of the pulp chamber was 2, 4, or 6 mm. Three millimeters of gutta-percha was removed from the three canals of one-half the teeth and amalgam was condensed into the canal space to a height of 7.5 mm above the cementoenamel junction (CEJ). The remaining teeth had amalgam condensed from the floor of the chamber to 7.5 mm above the CEJ.
Results & Discussion: Amalgam extension into the root canal space contributed minimally to the fracture resistance of the amalgam coronal-radicular restoration with four or more millimeters of chamber wall. If less than 4 mm of chamber wall height remained, however, the fracture load was substantially increased.
Conclusion: Amalgam extension into the root canal space should be confined to teeth with limited remaining pulp chambers (less than 4 mm of pulp chamber height).
45-003. Abrams, L. and Trachtenberg, D.I. Hemi-section: Technique and restoration. DCNA 18:415-44, 1974.
The following topics are discussed:
1. Posterior tooth root morphology.
2. Indications for root removal
The periodontal principal of strategic extraction
Control of compromised embrasure due to tight root proximity
Severe carious destruction
Endodontically untreatable roots
3. Indications for root separation
To divide the prognosis of the roots in a given tooth
To control the environment of the furcation
To eliminate untreatable carious and/or endodontic lesions
4. Contraindications for root removal and root separation
Inability to utilize treated tooth in an approximate (sic) restoration
Inability to treat the tooth endodontically
7. Restorative considerations
Abstractor's note: The author had a pompous, awkward, and redundant writing style, up with which, one would have difficulty putting.
45-004. Zmener O. Effect of dowel preparation on the apical seal of endodontically treated teeth. J Endodon 6:687, 1980.
Purpose: The purpose of this study was to evaluate the effect of dowel preparation on the apical seal of root canals obturated with sectional silver cones, or gutta-percha with lateral condensation and sealer cement.
Methods & Materials: 72 freshly extracted single rooted human teeth were prepared and assigned to three groups of 24 teeth each.
Obturation with 5mm sectional silver point or 4mm silver point and Grossman's cement
Lateral condensation of gutta-percha points and Grossman's cement
Same as group II
The teeth were immersed in an aqueous sol'n of 1% methylene blue dye for 72 hours. The teeth were then removed, sectioned, and analyzed.
Results & Summary:
The apical seal for a well fitted silver point is most vulnerable when a section of the cone must be removed during the dowel procedure.
In teeth obturated with lateral condensation of multiple gutta-percha points and sealer, apical leakage was reduced considerably as a result of increasing space between the dowel preparation and the apex. Additionally, leakage was considerably reduced when more than 4mm of gutta-percha filling remained in the apical portion of the canal.
No significant difference was found in teeth when the coronal portion of the root canal filling was removed immediately, as compared to 48 hours after root canal obturation.
45-005. Goerig, A.C. and Mueninghoff, L.A. Management of the endodontically treated tooth. Part I: Concept for restorative designs. J Prosthet Dent 49:340-345. 1983. Part II: Technique. J Prosthet Dent 49:491-497, 1983.
Purpose: To present a practical approach for restoring endodontically treated teeth.
Treatment will depend on these five criteria:
location of tooth in the arch
degree of coronal destruction
amount of occlusal stress
whether or not the tooth will be used as an abutment.
Anterior teeth are treated adequately with a bleaching treatment and composite unless there is considerable loss of coronal structure. Maxillary premolars and many second mandibular premolars should have cuspal coverage after RCT. If buccal and lingual walls are thin of if missing a lot of coronal structure, molars need cuspal coverage or a full crown. Amalgam post and core can be used in build-up and should extend into canals 1-2mm.
Seventy-five percent of root fractures occur on maxillary teeth due to lateral condensation force, seating of posts or inlays, over-preparation of canal access, or possibly electrolytic reaction between dissimilar post and crown metals. Ideal post space should be 2/3 the length of the root leaving at least 4mm of gutta-percha. Minimal tooth preparation should be done. The post should have a positive occlusal seat and fit passively. The author suggests an external bevel around the periphery to give a ferrule effect. The post may require a keyway incorporated in the canal to prevent rotation and a flattened portion or groove to allow cement to vent when seating. A prefabricated post should be 10-15mm long and parallel in shape to prevent a wedge-like effect on the tooth. Screw posts should be reserved for teeth with limited post space and a cemented post is recommended for all others. A serrated post has greater resistance to dislodgment.
The author proceeds to offer a possible technique in fabricating and cementing the cast core using the above criteria. He notes that composite resins generally have poorer marginal seals and recommends that resin was used to cement the post, a metal margin be implemented in the final crown. When investing the Duralay custom post pattern, 2mm extra water or no asbestos liner be used to produce a slightly smaller post. Communication between the restorative dentist and the endodontist is required so that adequate canal preparation is done for the desired restoration.
45-006. Deutsch, A.S., et al. Prefabricated dowels: A literature review. J Prosthet Dent 49:498-503, 1983.
Purpose: The purpose of this literature review is to review the literature concerning prefabricated dowels and evaluate several clinical properties associated with them.
I) Post retention:
The most retentive posts in decreasing order are parallel threaded, parallel serrated, parallel smooth, and smooth wedge-shaped.
Increased post length gave increased retention.
Cement used and diameter of post had little effect on retention.
Post design has a definite effect on the distribution of stress.
Sharp angles and countersinks should be avoided at the occlusal shoulder because they concentrate functional stresses.
III) Root fracture:
A post reinforces an endodontically treated tooth against horizontal root fracture.
Fracture and/or crazing of the root dentin can occur on post insertion if the post hole is not properly matched to the post.
IV. Post fracture:
A small increase in the post diameter imparts a vastly increased resistance to stress and therefore, post fracture.
Corrosion can occur when a tooth is restored with a a post, core, and crown of different metals.
The corrosion products will migrate into the dentinal tubules.
There exists strong circumstantial evidence but no direct experimental evidence linking corrosion with longitudinal fracture of the root.
45-007. Chan, R., and Bryant, R. Post-Core Foundations for Endodontically Treated Posterior Teeth. J Prosthet Dent Vol 48, 401-06, 1982.
Purpose: To compare the resistance to fracture and the failure characteristics of posterior endodontically treated teeth.
Materials & Methods: Fifty-five freshly extracted, single-rooted, mandibular premolar teeth were examined with transmitted light to confirm the absence of cracks or fractures. They were stored in saline except during operative , mounting, and testing procedures. The crown of each tooth was removed using water-cooled diamond disk and buccal and lingual planes formed at an angle of 130O between them. They were mounted in acrylic with a silicone liner. Three types of post-cores were constructed and tested after placing an uncemented full veneer crown. A compressive load was applied to the lingual incline of the buccal cusp of each crown by Hounsfield Tensometer metal plunger. Post-cores tested were: 1. Cast type III gold, 2. Amalgam/steel post combination, and 3. Composite resin/steel post combination.
Results/Discussion: Cast-gold specimens required less force before failure occurred. All cast post-core foundations showed displacement from the original cemented position, and most teeth showed evidence of root fracture. Amalgam and composite resin specimens commonly exhibited fracture of the core but showed less evidence of post-core dislodgment and root fracture.
Conclusion: The study supports amalgam and composite resin cores with cemented metal posts as acceptable alternatives to the cast-gold post-core foundation for endodontically treated posterior teeth.
45-008. Miller, A.W. Post and core systems: Which one is best? J Prosthet Dent 48:27-38, 1982.
Purpose: Categorize, compare and describe (1) threaded metal posts; (2) unthreaded metal posts; (3) plastic patterns and (4) combination kits.
(1) THREADED METAL POSTS (most controversial)
(+) very retentive
(-) significant levels of stress during fitting and placement
Which system is best? The answer varies according to the restorative situation and the skills and preference of the dentist. A post and core should not jeopardize remaining tooth structure
45-009. Larson, T.D. and Jensen, J.R. Microleakage of composite resin and amalgam core material under complete cast crowns. J Prosthet Dent 44:40-44, 1980.
Purpose: To study microleakage in vitro of composite resin core, amalgam core and crown preparations without a core material under complete cast crowns.
Materials & Methods: Ninety caries free extracted virgin premolars. Thirty with no core material; thirty with amalgam core (Caulk fine-cut); thirty with resin core (Concise); four ideally placed self-threading retention pins; type II gold; zinc phosphate cement; 2% fluorescein dye. Three groups of thirty subjected to the following variables:
group I - 24 hours post-cementation/thermally cycled
group II - 2 years/thermally cycled
group III - 24 hours uncycled
Results: Microleakage scored on an all or none basis after crown removal and sectioning of teeth. Thermal cycling induced microleakage when a core was present. Crowns without any core material were significantly better able to resist microleakage than those with.
Discussion: Possible explanation for differences: coefficients of linear expansion: Type II gold and tooth similar/14 & 11.4 cm/cm C; composite and amalgam 2-3 times that. Under thermal cycling, may expand more resulting in premature loss of cement seal. No difference in aging possibly attributed to lack of amalgam corrosion due to absence of salivary constituents and pH.
Summary & Conclusion: The results of this investigation indicate a need for further evaluation of core materials under cemented complete gold crowns.
45-010. Abou-Rass, M. Evaluation and clinical management of previous endodontic therapy. J Prosthet Dent 47:528-534, 1982.
The author reviews the criteria for acceptable endodontic treatment and the evaluation prior to restoration of endodontically treated teeth. Lack of symptoms does not indicate the success of endodontic treatment and each tooth should be evaluated for the quality of endodontic treatment to assure that it will provide a risk-free, permanent, solid foundation for the restoration
45-011. Abou-Rass, M. The stressed pulp condition: An endodontic-restorative diagnostic concept. J Prosthet Dent 48:264-267, 1982.
"Stressed Pulp" describes a vital pulp that has been subject to repeated damage, including operative trauma, accidents, or other pathologic changes. It is necessary that before preforming restorative dentistry that a comprehensive puplic health evaluation be done to include traditional pulp-test methods and a review of the past, present, and future treatment of the tooth. Those that indicate a stressed pulp should be treated prior to complex restorative dentistry.
45-012. Millstein, P.L., Yu H, Hsu, C.S. and Nathanson, D. Effects of cementing on retention of a prefabricated screw post. J Prosthet Dent 57:171-174,1987.
Purpose: To study the retention of posts using several different cements.
Materials & Methods: One hundred extracted teeth were prepared for Flexi-posts. The posts were cemented with zinc phosphate, Compspan, Crown Cementation Paste, or Flexi-post composite cement. The cements were injected into the canal. In half of each group, a lentulo spiral was used to more evenly and thoroughly distribute the cement.
Results: Zinc phosphate produced the highest separation forces. Both zinc phosphate and composite cements did equally as well on compressive and tensile strengths.
Conclusion: Cements significantly increased the retention of the posts. Spinning the cement with the lentulo spiral also improved retention. Use caution when using a screw post to avoid root fractures.
45-013. Liberman, R. et al. Restoration of posterior pulpless teeth: Amalgam onlay vs. cast gold onlay restoration. J Prosthet Dent 57:540-543, 1987.
This study showed that a cuspal coverage amalgam is a suitable restoration for endodontically treated teeth when properly used. When compared to cast onlays the amalgam showed more microcracks, and abrasion, but significantly less microleakage. Long term follow-up required to determine longevity.
45-014. Camp, L.R and Todd, M.J. The effect of dowel preparation on the apical seal of three common obturation techniques. J Prosthet Dent 50:664-666, 1983.
Laterally condensed gutta-percha, vertically condensed gutta-percha and Kloraperka showed no statistical difference in apical seal after dowel space preparation. Dowel space preparation with heat removal, Peeso drills and Gates Glidden drills also showed no statistical difference in apical seal. Root canals can be safely prepared for a dowel space to a level 5mm from the apex.
45-015. Kurer, H., Combe, E.C. and Grant, A.A. Factors influencing the retention of dowels. J Prosthet Dent 38:507, 1977.
Abstract not available
45-016. Lovadhal, P.E. and Nicholls, J.I. Pin-retained amalgam cores versus cast-gold dowel cores. J Prosthet Dent 38:507, 1977.
Abstract not available
45-017. Plasmans P J, et al. In vitro comparison of dowel and core techniques for endodontically treated molars. J Endon 12:382-387, 1986.
Purpose: To determine the in-vitro resistance level to oblique force of some amalgam systems that restored endodontically treated molars.
Materials & Methods: Two amalgam techniques were evaluated. Amalgam cores with cemented dowels and Amalgam core with no dowel. They were compared to cast post and core and amalgam core in non-endodontically treated molars.
12 teeth randomly divided into three experimental groups of 4 molars.
Cast dowel and core.
All amalgam core.
dowel plus amalgam core.
Each specimen was subjected to a slowly increasing force from the buccal side at 45 degrees to the long axis until the specimen could no longer withstand increasing load. Data analyzed by ANOVA.
Results: Intra-coronal reinforcement with a dowel did not significantly increase the in-vitro resistance level of amalgam cores. the control was also not significantly different. The Specimens within each group tended to fracture in a similar fashion.
Conclusion: This study supports:
Not removing too much remaining tooth structure to prepare tooth for a cast dowel and core.
All-amalgam or amalgam dowel cores are acceptable alternatives in comparison with cast metal dowel for the restoration of endodontically treated molars.
45-018. Kastenbaum F. The restoration of the sectional molar. Int J Periodontics and Restorative Dent 6:9-23, 1986.
Purpose: To present concepts for fabricating a restoration on sectioned multi-rooted teeth with clinically predictable results.
Discussion: Prosthodontic therapy differs with the degree of furcation involvement. The tooth preparation and the final restoration should eliminate the horizontal component of the roof of the furcation so as to eliminate the blind area where bacteria can be harbored. Class I furcation preparations are done by barreling in of the furcation during tooth preparation. Class II are often the most difficult to resolve because some cases can be treated with more extensive barreling in while others require sectioning of the tooth. Class III usually involves preparation of a sectioned tooth. Several factors must be considered. Caries, endodontic prognosis, root proximity and furca management. Goals of preparation are, no residual "lip", flat emergence profile, round flowing contours with a shallow concavity B-L and O-G, and prevention of a ledge at the corners of the roots. The provisional restoration should be a template for the final restoration in all aspects, including a test of the patients ability to maintain the restoration. Occlusal table is sometimes narrowed B-L. No post and core should be used unless tooth structure is absolutely inadequate to retain a casting. Splinting should be done if the remaining root or roots exhibit mobility or if the tooth is an abutment for an FPD. The use of a soft tissue master cast is discussed.
Conclusion: The key to success in the restoration of sectioned teeth is the patient's ability to maintain periodontal health.