The Law Offices of Edwin J Zinman DDS, JD, Inc. - Attorney offering dental malpractice legal services.



Overcontour

Crowns should replicate the natural tooth being restored. If the crown is larger than the natural tooth it will trap bacteria which can cause decay or periodontal gum disease.

Symptons of overcontour include bleeding gums around the crown or darkening of the gum margin around the crowns . Before turning bluish at the gum margin the gums at the crown margin may turn red and bleed. Healthy gums do not bleed either with or without crowns, bridges or veneers.

Malocclusion

After cementing the crown the dentist may need to make slight adjustments in the bite. If properly done it is usually not necessary to grind the opposing teeth in the opposing jaw. For instance, slight grinding of the new crown may occur for an upper crown but grinding the opposite lower teeth to accommodate the new crown should not be needed. Excessive grinding can trigger TMD (temporomandibular disorder) with painful jaw spasms in front of the ear or temple region and/or tinnitus (ringing in the ear).

Inadequate embrasure space

New crowns and veneers should have adequate space to floss between the teeth. If floss shreds or flossing is difficult or inaccessible the embrasure space between the adjacent crown or veneer is insufficient.

Biologic width space

New crowns should not impinge upon the underlying bone and connective tissue fibers overlying the bone. If crowns or veneers are prepared too deep underneath the gum, the gum tissue in time will become red, inflamed, recede, bleed or develop pathologic gum pockets. Periodontal crown lengthening surgery is often necessary to provide proper separation distance between the crown or veneer margins and underlining supporting bone and connective tissue. If not done, the crown or veneer continues to impinge upon the connective tissue to cause chronic inflammation.

Open Margin

A common error is cementing a crowns or veneers with unsealed margins that subsequently leaks and traps bacterial plaque with resulting decay and/or periodontal gum disease. Dentists should check circumferentially the crown or veneer with a sharp explorer both before cementation at a try in visit, and also after cementation to check for open unsealed margins. If marginal opening is diagnosed, the crown or veneer should be returned to the dental laboratory for construction of a new crown or veneer and not cemented permanently until remade.

Shy margin of preparation

A crown or veneer which does not completely cover the prepared tooth surface over which the crown or veneer is designed to be cemented is defective and requires a new crown or veneer with margins that are not shy or short of covering the prepared tooth surface. Shy margins predispose to tooth sensitivity. Also the exposed dentin surface of the incompletely covered restoration preparation is vulnerable to decay.

Color of crowns or veneers

Patients with the dentist's assistance can preselect a shade to blend with existing teeth or create an entirely new smile if multiple teeth will be crowned or veneered. A natural tendency is for the patient to select the whitest shade in the shade guide. If too white a shade is selected such as resembling refrigerator white, your teeth may not look natural. Whiter teeth can often be achieved with a reversible bleaching procedure rather than irreversible tooth reduction with crowns or veneers which require periodic replacement over a patientŐs lifetime.

Midline

Crowns or veneers should be centered so that the midline of the lips match the center line separating the right side from the left side. A disharmony between the crowns or veneers shifted to one side or another from the midline of the lips looks unnatural and unesthetic.

Cant

The upper crowned teeth should be at the same level as a ruler level with the center of each eye. Otherwise the teeth will be tilted to one side and not level with facial features. A face bow device, similar to a carpenter's leveler, should be used to establish a level plane of occlusion. It should be used before impression molds are sent to the dental laboratory for crown fabrications.

Longevity

Crowns or veneers are built to last for 10 or more years before wear or esthetic changes with adjacent teeth require new crowns or veneers. LUMINEERS and other minimally invasive veneer preparations do not invade sensitive dentin but instead are only drilled 0.3 to 0.5 mm into enamel. Veneers deep drilled into dentin and then bonded to dentin have a weak non-durable bond which is subject to fracture and debonding and thus are not built to last.

Bruxism

Patient grinding habits which can cause excessive teeth wear or clenching predispose to TMD (temporomandibular disorder) muscle jaw pain. Night guards worn over the teeth at night protect against excessive teeth wear on the biting surfaces.

Crown necessity

Decay or wear is the primary reason for crowning teeth. Overtreatment with excessive number of crowns is tempting for some dentists since crowns are the big ticket in a dentist's profit statement. If in doubt, select another dentist or prosthodontist specialist for a second opinion after first obtaining a written itemized estimate from the first dentist. To obtain a prosthodontist, consult the American College of Prosthodontists.

Alternatives

Bleaching and/or orthodontics is the most conservative, least invasive and least expensive alternative to crowns or veneers done for esthetic reasons for either whiter teeth or to close open spaces between teeth. Bleaching can be done at home with bleaching trays provided by the dentist to lighten or whiten teeth color. Removable braces such as clear Invisiline provide a permanent solution without grinding the teeth down to stubs for crowns. Invisiline may be completed in months and avoids destructive teeth preparation reduction necessary for construction of crowns.

Other alternatives include adding plastic restorative materials such as the newer composites which can be done in one sitting and avoids waiting weeks for the dental lab to construct crowns. For immediate esthetic needs, such as an upcoming wedding, plastic composites added onto existing teeth or crowns, which is often done in one visit, can provide a less expensive, quicker and yet long lasting result.

Veneers and root canals

Porcelain veneers only remove a portion of the facial outer enamel and some of the tooth side but avoids grinding strong enamel off entirely or the backside of the tooth. There is approximately one percent or less chance of a root canal from grinding the entire tooth for a crown. Root canals can be avoided entirely with porcelain veneers if correctly prepared into enamel only. If drilling is extended beyond the enamel into the less dense underlying sensitive dentin tooth structure, the risk of a root canal results because drilling into dentin is closer to the pulp nerve.

Prosthodontist specialist

Prosthodontists have completed two to three year specialty training in crown and bridge construction after dental school training. Most are members of the American College of Prosthodontists or may be Board certified as a diplomate of the American Board of Prosthodontics. The American Board of Prosthodontists lists certified Prosthodontists located near you.

Cosmetic dentistry

Cosmetic dentistry is not a recognized as a specialty by the American Dental Association since all dentists are trained to provide functional esthetic restorations.

So called institutes such as the Las Vegas Institute are not academic institutes in the traditional sense. Instead they offer commercial shorter courses such as weekend courses. One or two day courses do not qualify the dentist to announce to the public that the dentist is an ADA approved specialist. At least two or more years of postgraduate specialty training is required to qualify as an ADA recognized specialist. Also the dentist must pass numerous written and oral exams during training at a university affiliated institution. By contrast, no written exams or skill testing is usually required with short one, two day or one week courses.