Diagnosing, managing, and preventing cracked tooth syndrome.

Cracked tooth syndrome (CTS) can be a perplexing disorder to diagnose and manage. Many practitioners wonder whether the latest dental materials and adhesives can or should be used when restoring these teeth. The authors reviewed the literature and developed recommendations for how to diagnose and manage CTS and prevent it in susceptible teeth. As the population continues to age and people retain their teeth longer, it is anticipated that patients will present even more frequently with symptoms of CTS.

Aspects of wear and tear of tooth structure.

Lifestyle factors and the increased longevity of the dentition due to greater life expectancy have resulted in greater wear and tear (cracking) of teeth. Often there exists interplay between damage and repair. An understanding of these mechanisms of damage and repair will assist the clinician in correct diagnosis and treatment planning. Preventive strategies as well as interdisciplinary measures are required for optimal outcomes. However, are some of our restorative interventions causing further damage to tooth structure?

Application of biomimetic mineralization: a prophylactic therapy for cracked teeth?

Cracked teeth are usually found and easily ignored in clinic. If not found in time, they can lead to pulpitis and teeth fractures, which even can make the cracked teeth pulled out. The current treatments for cracked teeth include occlusal adjustments or preventive fillings, and the root canal therapy or complete crown restoration, which is decided according to the depth of cracks. However, the successful rate of preserving cracked teeth is less than 50% through occlusal adjustments and preventive fillings. Although the successful rate can reach 80% through the root canal therapy and complete crowns, the pulp and normal tooth can not be reserved. So the harms are very serious that prevention of its further development is extremely important. Nanobacteria have a very unique role in biological mineralization, which can produce crystalline apatites in the conditions of physiological calcium and phosphorus concentrations. Therefore, a hypothesis is put forward that application of nanobacteria may mineralize the cracks of teeth. Then the development of cracked teeth would be completely stopped.

Calculation of contraction stresses in dental composites by analysis of crack propagation in the matrix surrounding a cavity.

OBJECTIVES: Polymerization contraction of dental composite produces a stress field in the bonded surrounding substrate that may be capable of propagating cracks from pre-existing flaws. The objectives of this study were to assess the extent of crack propagation from flaws in the surrounding ceramic substrate caused by composite contraction stresses, and to propose a method to calculate the contraction stress in the ceramic using indentation fracture. METHODS: Initial cracks were introduced with a Vickers indenter near a cylindrical hole drilled into a glass-ceramic simulating enamel. Lengths of the radial indentation cracks were measured. Three composites having different contraction stresses were cured within the hole using one- or two-step light-activation methods and the crack lengths were measured. The contraction stress in the ceramic was calculated from the crack length and the fracture toughness of the glass-ceramic. Interfacial gaps between the composite and the ceramic were expressed as the ratio of the gap length to the hole perimeter, as well as the maximum gap width. RESULTS: All groups revealed crack propagation and the formation of contraction gaps. The calculated contraction stresses ranged from 4.2 MPa to 7.0 MPa. There was no correlation between the stress values and the contraction gaps. SIGNIFICANCE: This method for calculating the stresses produced by composites is a relatively simple technique requiring a conventional hardness tester. The method can investigate two clinical phenomena that may occur during the placement of composite restorations, i.e. simulated enamel cracking near the margins and the formation of contraction gaps.

Diagnosis, therapy, and prevention of the cracked tooth syndrome.

Many morphologic, physical, and iatrogenic factors, such as deep grooves, pronounced intraoral temperature fluctuation, poor cavity preparation design, and wrong selection of restorative materials, may predispose posterior teeth to an incomplete fracture. The resulting cracked tooth syndrome is frequently associated with bizarre symptoms that may complicate diagnosis and can persist for many years. Epidemiologic data reveal that splits or fractures are the third most common cause of tooth loss in industrialized countries, primarily affecting maxillary molars and premolars and mandibular molars. This finding indicates that the cracked tooth syndrome is of high clinical importance. Thus, at-risk teeth should be reinforced early, for instance by castings with cusp coverage or by internal splinting with adhesive ceramic restorations.

Changes in dentin after insertion of self-threading titanium pins with 3 methods: a scanning electron microscope pilot study.

STATEMENT OF PROBLEM: Inserting a self-threading pin can cause dentinal cracks, but it is not known whether dentin bonding agents can penetrate these cracks. PURPOSE: Part I of this in vitro pilot study was conducted to document the presence of dentinal cracks after the placement of self-threading pins with 3 methods. Part II was conducted to observe changes in dentin when a dentin bonding agent was applied before insertion of the self-threading pins. MATERIAL AND METHODS: The crowns of 14 noncarious third molars were sectioned horizontally 2 mm above the cemento-enamel junction, and the occlusal portions were discarded. The teeth were put into a nontransparent bag and divided randomly into 2 groups. Group 1 consisted of 12 teeth. In each tooth, 4 pinholes were prepared with a handpiece at normal rotation speed (30,000 rpm). Self-threading pins were placed into 3 of the pinholes in each tooth: 1 manually, 1 by handpiece at 7000 rpm, and 1 by handpiece at 30,000 rpm. The fourth pinhole was left empty and served as the control. All group 1 teeth were sectioned vertically through the pins, dental hard tissue, and control pin holes. The examination surface of each specimen in group 1 was polished, and the smear layer was removed with Calcinase and NaOCl solutions. After dehydration in ascending grades of alcohol, specimens were coated with a 10- to 15-nm-thick layer of gold and examined with a scanning electron microscope. In the remaining 2 teeth (group 2), a dentin bonding agent was introduced into the pinholes prior to pin placement. Two pins were placed manually and 2 by handpiece at 30,000 rpm. After pin placement, sectioning, cleaning, and dehydration, the specimens were examined with a scanning electron microscope, and x-ray mapping was performed to determine the presence of titanium, silicon, and calcium. RESULTS: Craze lines in dentin were associated with 54.5% of pins placed manually and 54.5% of pins placed with a handpiece at reduced speed (7000 rpm). Dentinal cracks were associated with 50% of pins placed with a handpiece at standard speed and with 16.7% of the control pinholes. X-ray mapping analysis revealed the presence of the dentin bonding agent between the pin and dentin wall. The dentin bonding agent was not found in the dentinal cracks except at the crack orifice. SUMMARY: Within the limitations of this pilot study, the method of pin insertion had no direct bearing on the presence of dentinal cracks. The dentin bonding agent tested did not fill the entire space of dentinal cracks but did occlude their orifices and fill the spaces between pin surface and dentin walls in the pin preparation.

Preservation of the roots--management and prevention protocols for cracked tooth syndrome.

It is essential that symptomatic fractures of teeth be suitably diagnosed to prevent propagation of the fracture and continuation of the symptoms. The importance of understanding the mechanism and progression of fractures within teeth is essential when considering the management of fractures within teeth. The relation of the fracture line to the pulp, periodontal ligament and root will influence the management protocols for the involved teeth. When does a Cracked Tooth Syndrome (CTS) become a cracked tooth i.e., unrestorable? Consideration is also required regarding when endodontic treatment should be commenced. Further, suitable-coronal restoration of teeth is required to prevent propagation of the fracture line and persistence of the symptoms. Patients diagnosed with CTS should be counselled in strategies to prevent CTS in other teeth.

Bonded restorations for the prevention and treatment of the cracked-tooth syndrome.

Several reports revealed that the cracked-tooth syndrome is a common problem in dental practice, which often results in extraction of the affected incompletely fractured teeth. Predominantly restored teeth suffer from these incomplete fractures. Therefore, it is of outstanding importance to stabilize teeth weakened due to cavity preparation. Besides full cuspal coverage by partial or full crowns, bonded restorations have been proposed for internal splinting of restored teeth. Although contradictory data have been published, there is evidence that bonded amalgam or resin-based composite restorations (RBC) do not increase fracture resistance of teeth with wide occlusal-proximal cavities to values similar to sound, unrestored controls. Indirectly fabricated RBC inlays and various ceramic inlays, however, increased fracture strength to levels as high as those of sound caries-free teeth. Therefore, it is recommended that weakened teeth with wide cavities be strengthened by full cuspal coverage with cast or ceramic restorations, by bonded ceramic inlays, or by indirectly-fabricated bonded RBC composite inlays.