Background: The advent of osseointegration and advances in biomaterials and techniques have contributed to increased application of dental implants in the restoration of partial and completely edentulous patients. Often, in these patients, soft and hard tissue defects result from a variety of causes, such as infection, trauma, and tooth loss. These create an anatomically less favorable foundation for ideal implant placement. For prosthetic-driven dental implant therapy, reconstruction of the alveolar bone through a variety of regenerative surgical procedures has become predictable; it may be necessary prior to implant placement or simultaneously at the time of implant surgery to provide a restoration with a good long-term prognosis. Regenerative procedures are used for socket preservation, sinus augmentation, and horizontal and vertical ridge augmentation.Methods: A broad overview of the published findings in the English literature related to various bone augmentation techniques is outlined. A comprehensi...

Bone augmentation techniques.

T echniques to reinforce endodontically treated teeth have been available for more than 100 years. However, few dentists have questioned the rationale that dictates automatic dowel reinforcement and coronal coverage of pulpless teeth. The difficulties of in vivo studies have motivated investigators to increase the number of in vitro studies of endodontically treated teeth. Although findings from in vitro studies provide guidelines, direct application of tensile, torque, and shear tests on experimental models or extracted teeth are questionable. This is particularly true if the elasticity of tooth structure, alveolar bone, and periodontal ligament is considered. The purpose of this study was to correlate clinical and laboratory studies of 1273 endodontically treated teeth in retrospect and determine the clinical significance of post reinforcement and coronal coverage. The location of the tooth in the arch and how it modifies the restorative requirements of an endodontically treated tooth are evaluated.

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Intracoronal reinforcement and coronal coverage: A study of endodontically treated teeth

Finite element analysis of a glass fibre reinforced composite endodontic post

Various concepts for dental treatment have been established without appropriate documentation, such as restoration of endodontically treated teeth. Some researchers and dentists strongly recommend including a post with the restoration to strengthen the root. Other studies have indicated that posts may substantially weaken the roots and should be avoided. An additional approach suggested that the post did not improve the resistance to fracture during occlusion and did not support the restoration. Biomechanical problems are analyzed, and a recommended clinical approach is presented.

Biomechanical considerations in restoring endodontically treated teeth

The clinical success of modern dental ceramics depends on an array of factors, ranging from initial physical properties of the material itself, to the fabrication and clinical procedures that inevitably damage these brittle materials, and the oral environment. Understanding the influence of these factors on clinical performance has engaged the dental, ceramics, and engineering communities alike. The objective of this review is to first summarize clinical, experimental, and analytic results reported in the recent literature. Additionally, it seeks to address how this new information adds insight into predictive test procedures and reveals challenges for future improvements.

Performance of Dental Ceramics Challenges for Improvements

A comparative study of restorative techniques for pulpless teeth.

Porcelain-veneered crowns are widely used in modern dentistry, and their fracture remains problematic, especially in all-ceramic systems. We hypothesized that substructure properties have a significant effect on the longevity of porcelain-veneered crowns. Flat porcelain/metal or porcelain/ceramic structures were cemented to dentin-like composite, and a mouth-motion cyclic load of 200 N was delivered by means of a tungsten carbide spherical indenter (r = 3.18 mm), emulating occlusal loading on crowns supported by dentin. Findings indicated that porcelain on a low-hardness gold-infiltrated alloy was vulnerable to both occlusal surface contact damage and porcelain lower surface radial fracture, while porcelain on a higher-hardness palladium-silver alloy fractured chiefly from occlusal surface damage. The advantage of a high-modulus metal substructure was less pronounced. Fracture in the porcelain/zirconia system was limited to surface damage in the veneer layer, similar to that in the porcelain/palladium-silver system. Bulk fracture, observed in veneered alumina layers, was not found for zirconia.

Fracture of Porcelain-veneered Structures in Fatigue

Ceramic restorations, whether monolithic (single layer) or porcelain-veneered, often chip and fracture from repeated occlusal loading Occlusion involves the opposing tooth sliding along the cuspal incline surface with an applied biting force (off-axis loading) We hypothesized that off-axis contact-load-slide-liftoff fatigue, as compared with normal axial fatigue loading, produces different fracture modes and fatigue lifespans of layered ceramics Monolithic glass plates were epoxy-bonded to polycarbonate substrates as a transparent model for an all-ceramic crown on dentin Off-axis and axial (control) cyclic loading was applied through a hard sphere in water, with a mouth-motion machine The off-axis loading is more deleterious for contact-induced occlusal surface fracture, but less harmful for flexure-induced cementation surface fracture of brittle layers than the axial loading This is because of the tangential load component associated with the off-axis loading Clinical relevance is discussed

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Damage Maps for Layered Ceramics under Simulated Mastication

Post designs may have a direct effect on fracture resistance of endodontically treated teeth. This in vitro study compared the resistance of three prefabricated threaded post systems with lateral shearing forces. After endodontics were completed, prefabricated posts were inserted according to the manufacturer's instructions. A silver amalgam core was placed, and extracted human teeth were prepared to a standard size with a 1 mm gingival chamfer finished on sound dentino A cast was fabricated and cemented, and the specimens were thermocycled. The test samples were secured to an Instron testing machine and loaded until failure. Fracture patterns were recorded, fractured surface areas were measured, and compressive stresses were calculated. However, there were no statistically significant differences among threaded posts in each test group.

Comparison of fatigue for three prefabricated threaded post systems

PURPOSE The aim of this study was to compare the debond/crack initiation strength (D/CIS) of a leucite-based low-fusing ceramic pressed (PC) to metal and feldspathic porcelain (FP) fused to metal. MATERIALS AND METHODS Forty rectangular metal specimens, 20 noble alloy (NA; gold-palladium) and 20 base metal alloy (BA; cobalt-chromium) were fabricated per ISO 9693:1999 standards (25.0 mm x 0.5 mm x 3.0 mm). Ten samples in each group received FP and the remaining 10 received PC. The samples in the PC group underwent wax pattern build-ups and subsequent investing and casting. The ceramic dimensions in all four groups were 8.0 mm x 1.0 mm x 3.0 mm. The final metal-ceramic specimen thickness was 1.5 mm. All specimens were subject to the Schwickerath crack-initiation three-point bending test at a crosshead speed of 1.5 mm/min. Metal-ceramic fracture loads were recorded in Newtons and D/CIS was calculated using the formula: tau(b) = k x Ffail. RESULTS Mean D/CIS were as follows: BA-FP: 36.11 +/- 2.31 MPa, NA-FP: 42.64 +/- 1.94 MPa, BA-PC: 37.47 +/- 6.02 MPa, and NA-PC: 47.94 +/- 3.92 MPa. A 2-way ANOVA revealed no significant difference in D/CIS values between the four groups. A statistically significant difference was noted when comparing the mean D/CIS values obtained between the two metal alloys used (NA: 45.29 MPa and BA: 36.79 MPa). CONCLUSION No differences (P > .05) in mean D/CIS were found between the low-fusing ceramic pressed to metal and the FP fused to metal. A higher mean D/CIS (P > .05) was found for the NA compared to the BA, with both ceramics tested.

Mitchell S. Pines

Papers

A comparative study of restorative techniques for pulpless teeth.

Fracture of Porcelain-veneered Structures in Fatigue

Damage Maps for Layered Ceramics under Simulated Mastication

Comparison of fatigue for three prefabricated threaded post systems

Ceramic pressed to metal versus feldspathic porcelain fused to metal: a comparative study of bond strength.