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What causes veneers to fail?

Veneers are thin shells made of porcelain or composite resin that are bonded to the front of teeth to improve their appearance. When done properly, veneers can dramatically enhance a smile by masking stains, closing gaps, changing the shape and color of teeth. However, like all dental restorations, veneers can fail over time. This article will examine the various factors that can lead to veneer failure.

Poor Oral Hygiene

One of the most common causes of veneer failure is poor oral hygiene. Veneers can trap plaque, which is a sticky film of bacteria that builds up on teeth. If plaque is not removed by brushing and flossing, it hardens into tartar that can only be removed professionally through scaling. Tartar below and around veneers creates an environment ripe for decay.

Cavities and decay below veneers will weaken the underlying tooth structure. This eventually leads to cracks in the veneer as the damaged tooth can no longer support the thin porcelain. Meticulous oral hygiene is required to prevent this type of veneer failure. Patients should brush twice daily with a soft-bristled brush and fluoride toothpaste. Flossing once daily is also essential to clean between veneers. Regular professional cleanings every 6 months remove tartar and protect veneer integrity.

Grinding and Clenching

Many people grind or clench their teeth, especially during sleep. This habit places extreme pressure on teeth that can fracture the brittle porcelain of veneers. Grinding and clenching, known as bruxism, can cause veneer cracks, chips, and breakage over time. Wearing a custom nightguard can help protect veneers from damage during sleep. Botox injections into the chewing muscles may also relax the muscles and curb bruxism. Stress management and taking breaks to rest the jaw during waking hours can further reduce grinding and extend veneer longevity.

Improper Veneer Placement

Veneers require proper tooth preparation and placement to achieve a lasting bond. If too much underlying tooth structure is removed, the remaining enamel may be too weak to durably bond with the veneer. This can result in debonding of the veneer. For adequate strength, most of the enamel should remain intact before veneer placement.

Over-contouring the veneer can also lead to failure. If veneers extend past the natural shape of the tooth, they are more prone to cracking and chipping from biting pressure. The biting edges of top and bottom veneers should be correctly aligned and smoothed to avoid fracturing. Irritation of the gums from over-contoured veneers may also loosen the bonding. Careful control of tooth reduction and proper veneer sizing can prevent these errors.

Bonding Issues

Veneers are adhered to the underlying tooth with dental bonding agents. If contamination or moisture affects the bonding process, it can result in a weakened bond. Saliva contamination is a common issue that can interfere with resin adhesion and reduce durability. Careful isolation and moisture control techniques are required during the bonding process.

Insufficient etching or bonding agent can also prevent complete bonding of the veneer to the tooth. This leads to gaps that allow bacteria and fluids to leak underneath, resulting in decay and eventual debonding. A meticulous and complete bonding protocol is key to creating a long-lasting veneer bond. Patients should verify their dentist follows all steps carefully when placing veneers.

Bonding to Composite Fillings

Veneers often require small fillings to repair defects prior to placement. Composite resin is commonly used for these fillings. But bonding veneers onto composite does not create as strong of a union as bonding to natural tooth enamel. The different materials have lower adhesion and are more likely to debond from each other. Porcelain adheres best to enamel, while composites bond more effectively to dentin. This mismatch in optimal bonding substrates reduces veneer longevity.

Insufficient Tooth Structure

Extensively damaged or decayed teeth lacking adequate enamel and dentin may not offer enough remaining tooth structure for durable veneer bonding. Teeth weakened by large fillings are also unfavorable for veneers. The thin shells require a solid foundation for support and retention. Attempting to place veneers on teeth with insufficient structure often leads to cracking or loss of the veneers. These teeth may be better restored with dental crowns to fully surround and strengthen them.

Trauma and Impact

The thin porcelain used for veneers is vulnerable to cracking and chipping from blows or trauma. Sports injuries, car accidents, falls and other impacts can easily fracture veneers. Chewing on hard objects like ice or nuts creates concentrated biting forces that frequently damage veneers. Patients with veneers must be vigilant about avoiding trauma and hard chewing. Protective mouthguards help shield veneers during contact sports. Patients should promptly repair any veneer cracks to prevent further failure.

Excessive Thinness

To maximize esthetics, dentists may over-prepare the teeth and create porcelain veneers that are exceedingly thin. Although thin veneers offer excellent translucency and blend seamlessly with surrounding teeth, they become fragile and prone to fracture. A minimum thickness of 0.3-0.5mm is required to prevent excessive cracking and chipping. Dentists must carefully control tooth reduction to allow room for adequately thick veneers.

Poor Occlusion

The way the upper and lower teeth fit together, known as occlusion, must be precisely balanced when veneers are placed. High spots or irregular contacts in the bite can create concentrated forces against veneers during chewing. This leads to cracks and damage over time. Carefully adjusting the bite with articulating paper ensures even contacts between top and bottom veneers. Selectively grinding the biting surfaces may be required to smooth out the occlusion and prevent veneer failure.

Parafunctional Habits

Habits such as fingernail biting, chewing on pens, opening packaging with one’s teeth and other parafunctional behaviors place undo strain on veneers. These activities generate excessive forces that can fracture the thin facings. Patients with veneers should be counseled to cease parafunctional habits to protect their new smile. Providing alternate behaviors, like chewing sugarless gum, often helps eliminate detrimental habits.

Poor Selection of Materials

Dentists have several options when selecting materials for veneers, including porcelain and composite resin. Composite veneers are more prone to staining, abrasion, and fracturing than high-quality porcelain. Selecting more durable porcelain materials minimizes the risks of veneer damage. Within porcelain, pressed ceramic veneers offer greater strength than layered porcelain. Dentists should choose material options appropriate for each patient’s needs and oral conditions.

Failure to Replace Loose Veneers

Over time, veneers may gradually debond or become loose due to lagging oral hygiene or grinding. Patients often attempt to re-cement these veneers themselves or put off repair. Allowing loose veneers to remain in place increases risk of tooth decay and further debonding. It also leads to poor esthetics as the veneers shift out of position. Early intervention to re-bond or replace failing veneers is critical to prevent additional complications. Regular dental visits facilitate detection of loose veneers.

Excessive Porcelain Additions

Although veneers offer the ability to reshape and recontour teeth, excessive removal of natural tooth structure should be avoided. Preparing for veneers should conserve as much enamel as possible. Massive reconstructions with extensive porcelain additions are more likely to fracture and debond than conservative veneers. The bulkier the veneers, the greater the leverage and strain placed on the bonding. Moderately sized veneers are more durable long-term.


When fabricated and placed properly, porcelain veneers can immensely improve smile aesthetics with reasonable longevity. However, veneers are delicate and prone to fracture over time, especially if not cared for diligently. Preventing veneer failure requires excellent oral hygiene, a strong bond to enamel, a smoothly contoured bite, durable materials, and avoidance of trauma. Patients should also refrain from habits that place excessive strain on veneers. With proper precautions and care, veneers can enhance one’s smile for many years. Regular dental exams help detect issues early before they cause veneer debonding or damage. Addressing problems promptly maximizes the chances of correcting them with minor interventions rather than complete replacement.

Cause of Veneer Failure Prevention Strategies
Poor oral hygiene Brush twice daily, floss daily, get regular professional cleanings every 6 months
Grinding and clenching (bruxism) Wear a nightguard, get Botox injections, manage stress, take jaw breaks
Improper veneer placement Ensure dentist does not over-reduce tooth or over-contour veneer
Bonding issues Use meticulous moisture control and bonding protocol
Bonding to composite fillings Minimize composite restorations prior to veneers
Insufficient tooth structure Crowns may be better option than veneers on weakened teeth
Trauma and impact Avoid trauma, wear mouthguard during sports, promptly fix cracks
Excessive thinness Retain adequate tooth structure for 0.3-0.5mm veneer thickness
Poor occlusion Carefully adjust bite with articulating paper
Parafunctional habits Stop harmful habits, redirect urge to chew gum
Poor material selection Choose durable pressed porcelain when possible
Failure to replace loose veneers Promptly re-bond or replace loose veneers
Excessive porcelain additions Conservative veneer preparation preserves tooth structure

Veneers provide an excellent means of aesthetically enhancing the appearance of front teeth. With diligent oral care and routine dental exams, veneers can serve patients well for many years before needing replacement. Avoiding known risk factors gives veneers the best chances of enduring long-term.