Restoration Injuries

Standard Of Care Crowns And Veneers

What is a crown?

A dental crown is a tooth-shaped "cap" that restores a decayed, broken, weak or worn-down tooth. Dentists also use crowns to cover dental implants and root-canal treated teeth. Made from a variety of materials including metal, resin and porcelain, on average crowns last between 10 and 15 years with proper care. The life span of a crown depends on the amount of wear and tear the crown is exposed to, how well you follow oral hygiene practices, and your personal mouth-related habits (you should avoid such habits as grinding or clenching your teeth, chewing ice, biting your fingernails and using your teeth to open packaging).

Dental crown preparation and placement

Preparing your tooth

To prepare your tooth for a crown, your dentist will need to remove some of your natural enamel. This makes space for your new crown and ensures that it will stay in place once bonded. Your dentist may also use a filling material to build up certain parts of your tooth. During this phase, the main goal is to create a strong foundation for your new crown.

Tooth Preparation For Crown Placement

Dental impressions

Next, your dentist will take impressions of your teeth. These may be physical impressions taken with a putty like material or digital impressions taken with a handheld scanner. Your dentist will send these impressions to a dental lab. There, a technician will use them to create your custom dental crown.

Temporary crown placement

It usually takes 2-3 weeks for a dental lab to make your new crown. While you wait on your final crown, your dentist will place a temporary one. Temporary crowns are usually made of resin or acrylic.

Placement of new crown

When the lab finishes your new crown, they will send it back to your dentist’s office so that an appointment can be made for the placement of the final crown. During this appointment, your dentist will remove your temporary crown and check its shape, color and fit. If you want to change something about your crown, like the shape, color or function, let your dentist know. The dentist is obligated to work with you and the dental laboratory to assure that the final crown is satisfactory to you before permanent crown placement. It is the responsibility of the dentist to confirm the marginal integrity of the new permanent crown before cementation.

What is a veneer?

A dental veneer is a custom-made shell that fits over the front surface of your teeth. They conceal cracks, chips, stains and other cosmetic imperfections. Preparation for veneers results in less damage to the individual tooth than preparation for crowns which are more invasive. Veneers are one of the most common dental treatments. There are several types of veneers available, depending on your specific needs.

Dental veneer preparation and placement

During your initial appointment, your dentist will examine your teeth and gums to determine if you are an eligible patient for veneers. If you are a veneer candidate, the dentist will prepare your teeth by removing a small amount of enamel from the facial (front) and interproximal (in-between) aspect of each tooth.

Next, the dentist will take impressions of your teeth. These impressions will be sent to the dental lab technician who will use these impressions to make your custom veneers (if you choose composite veneers, dental impressions will not be needed). If necessary, your dentist can place temporary veneers over the prepared teeth. After a few weeks, the dental lab will send the fabricated veneers back to your dentist. You will then be re-appointed for the placement of your permanent veneers.

During a second office visit, your dentist will check the shape, color and fit of your veneers. If you want to change something about your veneers, like the shape or color, let your dentist know. The dentist is obligated to work with you and the dental laboratory to assure that your cosmetic results are satisfactory to you before permanent veneer placement. Your dentist will ask you to confirm that you are happy with the cosmetics of the final veneers before the veneers are permanently bonded. After cementing the permanent veneers, the dentist will check your bite and make any necessary adjustments.

Most types of dental veneers are permanent, they are not reversible. Some veneers, such as no-prep or minimal prep veneers, are reversible. Since these veneers are reversible, we do not see poorly constructed reversible veneers in a dental malpractice lawsuit. On average, porcelain dental veneers should last between 10 - 15 years with proper care and maintenance.

Veneers vs. Crowns

A dental crown fits over your entire tooth. A veneer is a thin porcelain shell that covers the front surface of your tooth. The option that’s right for you will depend on your specific needs. Veneers are cosmetic in nature. They cover chips, cracks, discolorations and other esthetic concerns. Crowns are restorative in nature. The main goal is to improve the health of a tooth, but a crown can enhance the appearance of the tooth as well. The downside of a crown is that it removes a substantial amount of tooth structure which should be avoided when unnecessary.

An inlay or onlay can restore a tooth that is too damaged for a dental filling, but too healthy to warrant a crown. This type of restoration fits into the affected portion of your tooth like a puzzle piece.

Negligent Dental Restorations

Improper tooth preparation or inadequate placement of veneers or crown restorations can lead to several types of complications, including damage to the gums, bone or adjacent teeth, all of which can lead to pain, swelling, infection and sensitivity. Additionally, if the crown or veneer is not fabricated properly, bacteria or debris can leak into the tooth through gaps or imperfections in the restoration which can lead to infection and decay. Poorly fitting veneers or crowns can become loose or fall off, leading to additional restorative treatment. Negligent tooth preparation in the beginning stage of the restoration process can lead to pulp inflammation or infection, causing sensitivity, pain and insufficient tooth structure for properly fitting crowns. In this case, endodontic treatment (root canal) may be necessary.

Additionally, negligent tooth preparation and crown placement can cause periodontal injuries requiring a procedure called surgical crown lengthening, involving reshaping the gum and bone tissues surrounding a tooth to expose more of the tooth’s structure. Crown lengthening can be necessary if there isn’t enough of the natural tooth in place to hold the crown on its own. This can occur if a tooth is “overprepared”, meaning too much of the natural tooth structure was removed during the preparation process.

The following are types of restorative care injuries that can occur if performed improperly.

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. Symptoms of over contour 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). Failure of the upper and lower teeth to come together can create an open bite which will cause an inappropriate distribution of bite forces on the only teeth that come together when chewing food or at rest. In short, the natural occlusion has each of your teeth distributing the occlusal load and when the dentist creates a malocclusion, the dental forces are inappropriately distributed to just some teeth.

Anterior Open Bite Following Full Mouth Restorations

Changes In Vertical Dimension

It is common for a dentist who is recommending full mouth restoration that increasing the length of the teeth (vertical dimension) can provide the patient with a younger appearance. Vertical dimension is a critical factor in prosthodontics, playing a pivotal role in the functional and esthetic outcome of dental treatments. The standard of care requires that any dentist proposing a change in the vertical dimension with restorative dentistry place the patient in this proposed vertical dimension with temporary restorations for at least 4 months to confirm that the patient can tolerate the proposed change in vertical dimension. A change in the vertical dimension can impact facial proportions and esthetics as it affects the lower third of the face and influences the patient’s overall appearance. However, a change in vertical dimension can result in TMD (temporomandibular disorder) and phase one therapy prior to permanent cementation must be used by the dentist to confirm that a change in vertical dimension can be tolerated.

Inadequate Embrasure Space

New crowns and veneers should have adequate space to floss between the teeth and to leave room for the gingiva. If floss shreds or flossing is difficult or inaccessible, the embrasure space between the adjacent crown or veneer is insufficient. Inadequate embrasure space can lead to gingival necrosis and bleeding of the gums.

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 underlying supporting bone and connective tissue. If not done, the crown or veneer will continue to impinge upon the connective tissue and cause chronic inflammation.
(see Violations of Biologic Width category on the main page of this website)

Open Margin

It is dental negligence to cement crowns or veneers with unsealed margins that subsequently leak and trap 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 after cementation to check for open and unsealed margins. If a marginal opening is diagnosed, the crown or veneer should be returned to the dental laboratory for construction of a new crown 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 the tooth to 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 the proposed restorations with the patient’s existing teeth or create an entirely new smile if multiple teeth are 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 “Chicklets” 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 patient’s lifetime.

Midline

Crowns or veneers should be centered so that the midline of the face/lips match the center line separating the right side from the left side of the face. A disharmony between the crowns or veneers shifted to one side or another from the midline of the face/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, like 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. It is good practice prior to the destruction of the existing bite to recreate the baseline occlusion with study models mounted on an articulator with all relevant measurements for future reference.

Longevity

Crowns or veneers are built to last for 10 - 15 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 the patient to TMD (temporomandibular disorder) muscle jaw pain. Night guards worn over the teeth at night by patients with clenching or grinding 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. Patients provided with a full mouth restoration treatment plan should be given this treatment plan in writing which states the stages of treatment and the cost of same.

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. Zoom whitening in the dental office may also be a more effective and less expensive solution for whitening the patient’s teeth to a degree that the patient finds cosmetically acceptable. Removable braces such as clear Invisalign provide a permanent solution without grinding the teeth down to stubs for crowns. Invisalign 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 avoid 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, often done in one visit, can provide a less expensive, quicker, less invasive and yet longer-lasting result.

Veneers And Root Canals

Porcelain veneers only remove a portion of the facial outer enamel and some of the tooth side (interproximal) but avoids grinding enamel off the backside of the tooth. There is approximately one percent or less chance of needing 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-years of specialty training in crown and bridge construction after dental school. 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. A second opinion from a prosthodontist is recommended if the patient is considering a proposed full mouth restoration.

Cosmetic Dentistry

Cosmetic dentistry is not recognized as a specialty by the American Dental Association since all dentists are trained to provide functional esthetic restorations. Some dentists hold themselves out as being specially trained in cosmetic dentistry. They may display in their office “diplomas” from cosmetic dentistry institutes that suggest specialty training. These institutes of cosmetic dentistry offer commercial shorter courses, such as weekend courses. One or two day courses do not qualify these dentists to announce to the public that they are 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 are usually required with short one or two day or one week courses.