With patients becoming increasingly aware of the options available to them to improve their dental appearance, as clinicians we are able to provide them with multiple options to address their concerns. Dental veneers are one increasingly popular option, and are not without risk. 

It can be tempting for a clinician to embark on a veneer case with a high level of confidence, expecting it to be successful. This is especially so when the tooth preparation and scanning or impression are simple and quick, or where only a thin layer of composite is needed for direct veneers. While often considered a minimally-invasive procedure, veneers are not without significant risks, both to the patient and the practitioner.

Complaints and claims relating to veneer treatment may be based on subjective rather than clinical factors. In the absence of sound clinical grounds for a patient being unhappy with the treatment he or she has received, it can be incredibly difficult to determine what should be done (if anything) to assist the patient and attempt to resolve those concerns. This is especially so when the clinician has excellent records and the photographs of the completed case suggest the patient has a significantly improved and highly aesthetic smile. At Dental Protection we regularly speak to members who have encountered difficulties with a veneers case and who are seeking a quick resolution. Unfortunately, as we will explore below, quick fixes are not always possible.

Where an unhappy patient has sought redress via regulatory channels only to be rebuffed, it is not uncommon for them to then escalate their complaint as a dentolegal claim. This can result in a protracted and expensive resolution process in many instances.

We encourage clinicians to consider even the apparently simplest single or double veneer case as complex dentistry in the first instance. Such treatment via this paradigm will assist in ensuring careful planning, consent and clinical treatment all occur.

What are dental veneers? 

Veneers are thin layers of restorative material applied to the visible (usually facial, but sometimes also incisal) surfaces of the teeth in the appearance zone. Their function is to improve the colour, translucency, lustre and form of the teeth, particularly when smiling. Rarely are veneers required to improve speech or mastication and if they are, these cases can prove particularly challenging, given occlusal changes can prove difficult for a patient to adapt to and changes can prove to be dynamic in nature.

Veneers are constructed either of direct or indirect materials. Direct materials are almost always composite resin bonded directly to tooth enamel. Ceramic materials are used for indirect veneers, being either feldspathic porcelain or, more commonly, lithium disilicate. The decision to use one approach over the other is made in consultation with the patient and is based upon the aesthetic requirements of the case as well as criteria of cost, repairability and longevity.

Generally, direct veneers provide advantages of lower clinical time, repairability, avoidance of some or all laboratory fees, and lower cost to the patient. However, they are difficult to maintain in terms of staining, polish/surface lustre and may be prone to chipping or cracking. Ceramic veneers provide advantages in terms of improved aesthetics (in most instances), a very high level of lustre and translucency, greater strength (where lithium disilicate is used) and reduced maintenance, since their surface glaze is much less prone to staining. However, should they chip or crack, they are difficult to repair and may require full replacement, which at times can be problematic in terms of matching the shade to the adjacent veneers. Ceramic veneers no longer require significant tooth preparation and may be made as little as 0.3mm in thickness. One of the chief potential advantages of ceramic veneers is simply that the aesthetic characteristics of the veneers are able to be delegated to the technician (ceramist), bypassing the clinician’s need to determine shade and form in real time and, occasionally, helping to overcome a clinician’s lack of aesthetic insight. It can be much easier to look at models or scans to achieve a balanced aesthetic outcome and good incisal contacts than do this on a patient in the chair, where time pressures and patient management issues can prove demanding. 

All veneer types perform best when bonded to sound enamel and this is of greatest importance at the margins. Like other restorations, veneers will have a finite life, with ceramic veneers being expected to last longer than composite veneers. Longevity may vary, being less in patients with heavy anterior occlusions, parafunctional habits or robust diets. Indeed, Magne et al has reported that the success rates of ceramic veneers can drop to about 60% in patients exhibiting bruxism activity compared to 90% or more in those without. 1 

As with all dental procedures, careful case selection is key and any failure by a clinician to diagnose and manage underlying causes of past tooth structure deterioration or loss may greatly increase the risk of treatment complications and adverse outcomes.

What problems can arise in veneer cases? 

Dental veneers have a high probability of survival overall according to the dental literature, with a recent paper noting this to be greater than 90% over more than ten years2. However, veneer survival does not necessarily equate with success, as many surviving veneers exhibit staining, chipping or other cosmetic or functional issues. The significance of such complications can be remarkably subjective with some patients accepting these problems as an inevitable part of an ageing dentition, while others voicing immense dissatisfaction over the slightest irregularity.

Therefore, problems might best be examined from two perspectives: clinical factors and human factors. This article will consider the clinical factors, with the human factors being considered in the next edition.

Clinical factors 

Complaints and claims can arise from a variety of clinical factors, including: 

An obvious poor aesthetic outcome 

Where the size, shape, shade and other characteristics of the veneers do not sit harmoniously within the remaining dentition. Given that the primary reason for placement of veneers is to improve the appearance of a patient’s smile, any failure to achieve an acceptable aesthetic result is likely to result in disappointment, frustration and (at times) a complaint. 

As anterior aesthetics are a combination of the white (tooth structure), pink (gingival architecture and display) and black (interdental and/or interocclusal spaces such as black triangles associated with receded papillae) aspects visible during smiling, the veneers alone may not be the primary source of an aesthetic complaint. At Dental Protection we have encountered cases of the veneers themselves looking “perfect” yet being rejected based on a perception of a lack of symmetry due to a difference in height between the gingival margins of the 12 and 22 teeth. Ironically, such a height discrepancy had never been raised by those patients as part of their concerns about their smiles until everything else was harmonious and beautiful.

Patients often request very white veneers in order to obtain a more youthful, “Hollywood” smile. Despite mockups being made to show patients and seek their approval, the actual aesthetics of such a smile can come into question on the day of issue or sometime soon afterwards. We are aware of instances of veneers being rejected because they seem too white, with such a shade originally being demanded by the patient despite the dentist’s recommendations to the contrary.

To avoid the risk of “shine through” of darker underlying tooth structure, it is imperative that the dentist provides the laboratory with photographs of the teeth before and after preparation with accompanying shade tab information being visible. This will enable the technician to select a material that will adequately mask the discolouration, ideally without appearing too opaque in the mouth. It is wise for the clinician to consult with the laboratory during the planning stages of the case to best determine the minimum thickness of ceramic necessary for masking as this may impact on the depth of tooth preparation or may result in a decision not to proceed if this risks loss of too much tooth structure.

Similarly, where direct veneers are placed, an opaquing layer may be required to mask out underlying tetracycline staining or similar heavy discolouration. Space needs to be allowed for that layer and/or the use of an opaque base shade of composite. Consideration of the space available for this needs to occur prior to embarking on the case as it may not be possible to adequately mask tooth colour without considerable bulk or placement of a dull, lifeless veneer. Loss of colour stability, marginal staining, minor chipping, air bubbles and dulling of the veneer surface are all common over time. This can result in patients expressing dissatisfaction with aesthetics from around twelve months after their placement. We recommend regular follow up of these cases and that a discussion around ongoing maintenance requirements for veneers is included as part of the consent process.

Premature failure

Veneers (whether composite or ceramic) can debond due to a failure in the adhesive (adhesive failure), a failure within the material itself leaving a thin layer of material attached to the tooth (cohesive failure) or a combination of the two. When more than one veneer debonds, patients may then have (quite understandable) doubts about how long the remainder of the veneers will last and we have found patients lodging a claim for the replacement of all six or eight veneers when only one or two have failed to date. Members can encounter difficulties explaining to patients the reasons for premature failure especially if those risks were not discussed in the consent process and where instead a prediction was given that the veneers would typically last perhaps five or ten years.

Failure can also arise from the development of cracks within the restorative material, staining in those cracks or around the margins, chipping of incisal edges or (typically) distoincisal corners, loss of surface lustre, colour change (particularly if veneers have been adhered using non-colour stable resins), marginal leakage (usually a sign of adhesive failure and unfavourable dietary habits) and caries. 

At Dental Protection we strongly recommend that any warranty provisions on aesthetic treatments are clearly discussed and documented at the time of the consultation and planning of the case. Patients should be provided with written information about the risks of failure, the costs of repair or replacement and who will be responsible for those costs should they arise. If a clinician provides a warranty or prediction of the lifespan of the veneers, any conditions inherent to that estimate ought to be expressly noted. We have encountered cases of dentists making patients nightguards to protect veneers from bruxism-related nocturnal forces, but where the use of that protection seems sporadic at best. Who is responsible for any failure then? The patient may insist that the guard was worn, or was unable to be worn due to being too tight and uncomfortable, while the dentist may insist that the non-compliance has caused a debond without knowing for sure that this is the case.

Debonding may also arise in ceramic veneers from a failure to adequately etch the ceramic prior to cementation. Clinicians should be confident about the bonding protocols required and, if necessary, confirm with their dental laboratory whether the veneers have been pre-etched if this is not self-evident from a matte intaglio surface.

Pulpal symptoms 

It can be difficult explaining to a patient why one or more of their teeth are sensitive following veneer preparation when the teeth had been asymptomatic until treatment commenced. Although prolonged sensitivity following veneer preparation and/or placement is uncommon, in situations where sensitivity persists for weeks and temporary veneers have been recemented (to help address leakage concerns) it may become necessary to consider endodontic management of any pulpitis.

For this reason, at Dental Protection we recommend that the risk of pulpal symptoms arising during or subsequent to veneer placement should be expressly discussed with the patient as part of the consent process. That discussion should outline the implications of pulpal symptoms arising, who will be responsible for any costs, and also whether it may be necessary to then revise the restorative treatment plan. The latter issue is quite common in teeth with preexisting mesial and distal composite restorations which, following endodontic access, may be structurally weakened and hence require a post core and crown rather than a veneer.

While it is impossible to avoid sensitivity altogether, a commonsense clinical approach to minimising risk will usually include: 

• Avoidance of preparation of teeth with a history of past sensitivity to temperature or biting until such symptoms have been absent for an acceptable period. Cracks require careful investigation and (possibly) stabilisation until teeth are no longer symptomatic. 

• Minimal preparation of tooth structure, ensuring enamel is not breached through to dentine wherever possible 

• Ensuring copious water spray is used during all tooth preparation and finishing of the veneers to avoid overheating 

• Minimal use of haemostatic agents during any gingival retraction

• Strict adherence to manufacturers’ bonding protocols, including avoidance of overdrying of tooth structure following etching and ensuring sufficient application of adhesive to eliminate voids and reduce risk of microleakage 

• Careful occlusal adjustment to ensure specific teeth are not overloaded, particularly in excursive movements. 

It goes without saying that dental veneers were once a stronghold of minimally invasive dentistry but seem to have diverged amongst some clinicians to become significantly invasive. It is becoming more commonplace for clinicians to prepare almost a “three-quarter” preparation on anterior teeth so that multiple issues (such a slightly protruded, rotated or otherwise misaligned teeth) can be addressed restoratively without additional orthodontic correction. While this may seem helpful in terms of minimising time and cost for patients, aggressive tooth preparation is more likely to result in biological complications like pulpitis, besides causing obvious weakening of the teeth themselves. There is no robust evidence to support aggressive tooth preparation as a means of “strengthening” veneers and if a patient’s occlusal conditions mean that normal thickness veneers might be unsuitable, it might be argued that the clinician should consider other restorative options that are likely to provide greater chances of clinical success.

As with any planned crown and bridgework, pre-operative radiographic assessment of teeth to be restored (and adjacent teeth where their condition might impact the treatment plan) is a routine aspect of planning but also best practice. It is essential to establish the baseline condition of teeth prior to treatment as this can help identify underlying issues that might adversely affect treatment outcomes. We recommend pulp sensibility testing in conjunction with radiography to adequately establish the pre-operative pulpal status of any teeth to be treated. Due to blurring in the midline on many OPGs, periapical imaging is preferred where veneers are planned for incisor teeth.

Gingival recession and exposure of margins

This is more commonly seen in patients with thin, soft tissue biotypes, active periodontal disease, aggressive toothbrushing habits or in bruxers. Careful management of the gingival margins may reduce this risk and may involve minimal (if any) soft tissue retraction, especially where margins are able to be kept supragingival and in sound enamel. Of course, this may not be possible in cases where the tooth shade is being changed significantly and avoidance of a dark visible margin is essential. Careful atraumatic finishing of margins is essential, ensuring removal of all adhesive excess/flash to avoid later marginal inflammation and plaque traps.

Again, the possibility of recession occurring over time can be significant and cause patient dissatisfaction, especially in patients with a high smile line or with discoloured roots, given it may make the presence of the dental restorations more obvious and also result in increased risk of cervical hypersensitivity. Consent processes should include a discussion of this risk, its management, and how in certain situations replacement of the veneers in the future could be required simply due to the patient’s natural ageing. It can be difficult to reliably determine the aetiology of such recession as although it is strongly correlated to patient factors, it can be unpredictable.

Tooth movement and/or poor fit 

There remains some debate around whether the breaking of contact points between anterior teeth (where there are no pre-existing diastemas and where they may be a desire to alter the position of the contacts to improve tooth shape or midline position restoratively) may allow tooth movement between the preparation and placement of indirect veneers. Certainly there should be minimal movement if contact points are not opened during tooth preparation, but some tooth movement over time is always possible. This does not seem to be an issue for direct veneers for obvious reasons.

We are aware of cases where a clinician has gone to fit veneers, only to find (after adhering several of them) that the remaining veneers won’t seat. This may be from tooth movement between appointments, inaccuracies between the impression/scan and the working model, path of insertion issues, clinician error in placement of veneers already in situ, or technician error.

A commonsense approach to minimising this risk may include: 

• Placement of direct veneers rather than indirect ones if this will achieve the treatment objectives. 

• Ensuring contact points are only opened where the clinical benefits outweigh the risks. It remains sensible to keep tooth preparation to a minimum if this will not adversely affect final aesthetics and hygiene practices.

• Ensuring the impression or scan provided to the laboratory is free of any visible marginal discrepancies. The author has seen cases of clinicians supplying multiple impressions to a laboratory where, say, five teeth on one impression are correctly recorded and the remaining three teeth recorded in a second impression, with the dentist expecting the laboratory to “merge” these impressions correctly to achieve a full eight units. This is a recipe for error.

• Placing well-fitting temporary veneers on teeth where indicated. This may reduce the risk of tooth movement between visits 

• Ensuring teeth to be treated are periodontally stable and healthy as well as free of occlusal interferences 

• Trying in all ceramic veneers together to not only confirm fit but also determine if there is a particular order of insertion necessary to ensure all veneers will fit. Your laboratory will usually indicate if a specific order of insertion is required due to path of insertion variances between teeth, but this ought not to be taken for granted. Any concerns around fit can be addressed via adjustments prior to cementation and thereby reduce the risk of complications later 

• Cementation of pairs or even the full set of veneers at one time, carefully clearing contact points prior to curing, so that errors in placement are minimised. This is not recommended for inexperienced clinicians due to the need for very careful technique and the risk of an “all or nothing” failure. 

• Careful cleanup of all excess adhesive after each veneer is placed to avoid overhangs or thin proximal films of adhesive that might adversely impact the correct placement of adjacent veneers. Use of thin Teflon tape on adjacent tooth surfaces can assist in minimising contamination of the adjacent tooth surfaces and improve speed of cleanup. 

Loss of temporaries

This is, in itself, rarely a major issue of concern unless the patient has had a social engagement where it has caused embarrassment, or the teeth have been sensitive between appointments where tooth structure has been exposed. However, we have encountered cases where the repeated loss of temporary veneers has resulted in patients losing confidence in the clinician’s ability to complete the case, attributing such failure to be an indication that the final veneers will also be prematurely lost because the dentist lacks the skills and knowledge to adhere them correctly.

As mentioned above, premature loss of temporaries may in some instances increase the risk of minor tooth movements and hence increase the risk of misfits.

Of note, these clinical issues do not always occur in isolation, and it is not unknown for there to have been a history or problematic fit of veneers, requiring remaking, only for the patient to then experience sensitivity and gingival complications later. If one or more of those veneers subsequently is lost, it is almost inevitable that the patient will doubt the quality of the dentist’s care and question the longevity of their overall treatment. This may result in a request for a full refund, payment towards specialist retreatment, or an additional claim for damages.

Veneer treatment can be rewarding, and we hope this exploration of some of the clinical factors helps them remain so. The veneer check list that follows has been designed to support you in a hassle free and predictable practice.

References 

1 Magne P, Perroud R, Hodges JS, Belser UC. Clinical performance of novel-design porcelain veneers for the recovery of coronal volume and length. Int J Periodontics Restorative Dent. 2000;20:440–457 

2 Alghazzawi TF. Clinical Survival Rate and Laboratory Failure of Dental Veneers: A Narrative Literature Review. J Funct Biomater. 2024 May 16;15(5):131. doi: 10.3390/jfb15050131. PMID: 38786642; PMCID: PMC11122289.