Long-Term Survival and Complication Rates of Porcelain ...

The presented study aimed to assess the survival rate of porcelain laminate veneers (PLV) based on a systematic review of the literature. An electronic search was last updated in February . Eligibility criteria included clinical series of patients rehabilitated with PLVs published in the last 25 years, with a minimum follow-up of 3 years. Survival analysis methods were applied. Twenty-five studies were included, with PLVs. The 10-year estimated cumulative survival rate (CSR) of PLVs was 95.5%. The 10-year CSR of PLVs when fracture, debonding, occurrence of secondary caries, and need of endodontic treatment were considered as isolated reasons for failure were 96.3%, 99.2%, 99.3%, and 99.0%, respectively. PLVs without incisal coverage had a higher failure rate than PLVs with incisal coverage. Non-feldspathic PLVs performed better than feldspathic PLVs. As a conclusion, the 10-year CSR of PLVs was 95.5%, when fracture, debonding, occurrence of secondary caries, and need of endodontic treatment were considered as reasons for restoration failure. Fracture seems to be most common complication of PLVs, followed by debonding, with both more commonly happening within the first years after PLV cementation. PLVs with incisal coverage and non-feldspathic PLVs presented lower failure rates than PLVs without incisal coverage and feldspathic PLVs.

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Although preserving more tooth structure, PLVs are not without problems, and different factors can influence the survival rate of these restorations. These factors include, among others, the preparation design, the tooth vitality, the type of porcelain material, and the adhesive system used. Furthermore, the survival rate of PLVs is believed to be influenced by parafunctional activities, such as bruxism [ 5 ]. Failure of PLVs can be manifested by several biological and mechanical problems, such as porcelain fracture, debonding, periodontal disease, caries, and tooth fracture. Some clinical trials observed that the most common reasons for PLV failure were fracture and debonding [ 6 , 7 ].

Another common treatment alternative is based on full coverage of the tooth structure with crown restorations. Historically, crown restorations were the preferred option for treating many esthetic problems, since they require full tooth coverage, which could offer better retention and esthetics compared to direct fillings. However, tooth preparation for these restorations may be considered an invasive approach, in many cases with the removal of a considerable amount of sound tooth structure [ 3 ].

The mean, standard deviation (SD), and percentages were presented as descriptive statistics. The interval survival rate (ISR) of PLVs was calculated using the information for the period of failure extracted from the included studies, and the cumulative survival rate (CSR) was calculated over the maximal period of follow-up reported, in life-table survival analyses having (a) PLV fracture, (b) PLV debonding, (c) occurrence of secondary caries, and (d) need of endodontic treatment as reasons for failure, as well as for failure considering these four reasons together. Failure between PLV preparations with or without incisal coverage was compared by log-rank test (Kaplan&#;Meier). All data were statistically analyzed using the Statistical Package for the Social Sciences (SPSS) version 26 software (SPSS Inc., Chicago, IL, USA).

Quality assessment of the case series was executed according to the Quality Assessment Tool for Case Series Studies of the National Institutes of Health (NIH) [ 11 ]. The NIH quality assessment tool calculates the study quality on the basis of nine criteria. The ratings on the different items were used by the reviewers to assess the risk of bias in the study due to flaws in study design or implementation. The studies were classified as &#;good&#;, &#;fair&#;, or &#;poor&#; quality. In general terms, a &#;good&#; study has the least risk of bias, and results are considered to be valid. A &#;fair&#; study is susceptible to some bias, deemed insufficient to invalidate its results. The fair quality category is likely to be broad, so studies with this rating will vary in their strengths and weaknesses [ 11 ]. A &#;poor&#; rating indicates significant risk of bias. Studies of &#;good&#; quality were judged to have at least seven points.

Two authors independently extracted data using specially designed data extraction forms in an Excel file. For each of the identified studies included, the following data were then extracted on a standard form, when available: year of publication, study design, study setting (private clinic, University), country where the study was conducted, recruitment period of the patients, number of operators, number of patients, patient&#;s sex and age, location of the PLVs (maxilla/mandible), teeth restored (incisor, canine, premolar, molar), preparation with or without incisal coverage, PLV preparation design, type of porcelain used (feldspathic, non-feldspathic), adhesive system used, tooth vitality, definition of failure, presence of bruxers in the cohort, complications, and follow-up period. Contact with authors for possible missing data was performed.

The titles and abstracts of all reports identified through the electronic searches were read by the authors. For studies appearing to meet the inclusion criteria, or for which there were insufficient data in the title and abstract to make a clear decision, the full report was obtained. Disagreements were resolved by discussion between the authors.

An electronic search without time restrictions was undertaken in May , with an updated search carried out in February , in the following databases: PubMed/Medline, Web of Science, and Scopus. The following terms were used in the search strategies: (&#;ceramic veneers&#; OR &#;porcelain veneer&#; OR &#;indirect veneer&#; OR &#;laminate veneer&#; OR &#;veneer restorations&#; OR &#;dental veneer&#; OR &#;veneer&#;) AND (&#;survival&#; OR &#;survival rate&#; OR &#;survival analysis&#; OR &#;dental restoration failure&#; OR &#;prosthesis failure&#; OR &#;success&#; OR &#;success rate&#; OR &#;complications&#; OR &#;prognosis&#; OR &#;long term&#;).

The comparison of the failure rates between PLVs fabricated with different porcelains (for when the information on the time-point of failure was available) resulted in a statistically significant difference (p < 0.001, log-rank test), with PLVs made of non-feldspathic porcelain (failures: 40 out of ) performing better than feldspathic PLVs (failures: 66 out of ). When the cases with, as well as the cases without, information on time-point to failure were considered, 109 out of non-feldspathic PLVs failed, in comparison to 275 out of feldspathic PLVs.

Although the number of PLVs failures with (213/) and without (157/) incisal coverage in relation to the total number of PLVs in each group was known, a survival analysis comparing both groups was not possible since there was no information on the time-point of failure for any of the PLVs without incisal coverage.

Pooled data from the PLV2 with information on follow-up in relation to PLV fracture (only &#;cracked&#; PLVs were not included here) ( Table S3 ) showed that most of the failures due to the occurrence of this complication happened within 2 years after PLV cementation. The 10-year CSR was 96.3% when fracture, only, was considered as a reason for PLV failure. Pooled data from the PLVs with information on follow-up in relation to debonding ( Table S4 ) showed that most of the failures due to the occurrence of this complication happened within 2 years after PLV cementation. The 10-year CSR was 99.2% when debonding, only, was considered as a reason for PLV failure. Pooled data from the PLVs with information on follow-up in relation to secondary caries ( Table S5 ) showed the failures due to the occurrence of this complication happened after 5 years from the PLV cementation. The 10-year CSR was 99.3% when secondary caries, only, were considered as a reason for PLV failure. Pooled data from the PLVs with information on follow-up in relation to post-cementation need of endodontic treatment ( Table S6 ) showed that most of the failures due to the occurrence of this complication happened between 3 and 7 years after PLV cementation. The 10-year CSR was 99.0% when endodontic treatment, only, was considered as a reason for PLV failure.

As for complications, fracture was reported in 154 PLVs in 18 studies, chipping in 31 PLVs in seven studies, cracks in 56 PLVs in seven studies, debonding in 85 PLVs in 14 studies, need for endodontic treatment in 16 cases in seven studies, and secondary caries in eight cases in five studies. Chipping and cracks were not always considered as &#;failure&#; in the studies; in most occurrences these complications were considered as &#;failure&#; only in the cases when the defect was irreparable. In order for a &#;fracture&#;, &#;chipping&#;, or &#;crack&#; to be considered a failure, the present study took into consideration only the occurrences for which the defect was irreparable, i.e., the PLV needed to be replaced. Taking four complications together (PLV fracture, PLV debonding, occurrence of secondary caries, and need of endodontic treatment), 433 out of PLVs failed. Pooled data from the PLVs with information on follow-up in relation to failure ( Table S2 ) showed that most failures happen within the first years after bonding, and the 10-year CSR was 95.5%.

The PLVs were made of feldspathic porcelain in 12 studies (50.0%), of non-feldspathic porcelain in nine studies (37.5%), three studies evaluated PLVs of both porcelain types (12.5%), and for one study this information was not available. In 17 studies (73.9%) the design of the PLVs included incisal coverage, while in two studies there was no incisal coverage, and four studies included both types of preparation (no information was available in two studies).

A total of PLVs were evaluated, mean ± SD of 260 ± 199 PLVs (range 24&#;736) per study. The information about the distribution of these PLVs between the jaws was available for 21 studies, with in the maxilla (78.6%) and in the mandible (21.4%). Five out of these 21 studies evaluated PLVs only in the maxilla, and 16 studies in both arches. There were PLVs placed in central incisors (38.7%; maxilla/mandible: /242), in lateral incisors (30.6%; maxilla/mandible: 830/224), 842 in canines (24.4%; maxilla/mandible: 613/193, not mentioned: 36), 207 in premolars (6.0%; maxilla/mandible: 173/34), and nine in molars (0.3%; maxilla/mandible: 5/4). No information regarding the tooth type was available for the other PLVs. A mean ± SD of 189 ± 127 PLVs (range 24&#;426) per study (n = 21) were cemented in the maxilla, and 68 ± 57 PLVs (range 6&#;195) per study (n = 16) in the mandible.

Twenty-five studies [ 5 , 6 , 7 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ] were included in the present review, published over a period of 24 years (&#;). A detailed description of the included studies is shown in . Seventeen studies (68.0%) were retrospective, seven prospective, and one a randomized controlled trial. Thirteen of these studies were conducted in a University setting (52.0%), seven at private clinics, one at both these environments, and for four studies the information was not clear about the location.

Only two out of the 25 included studies were not considered to be of high quality ( ). These studies scored a little less than the others, due to factors such as &#;Were the statistical methods well-described?&#; Still, these two studies [ 12 , 13 ] provided enough detailed data on clinical outcomes, which was not deemed to sufficiently invalidate their results.

The study selection process is summarized in . The search strategy in the databases resulted in papers. One hundred and sixty one articles were cited in more than one database (duplicates). The reviewers independently screened the abstracts for those articles related to the aim of the review. Of the resulting studies, were excluded for not being related to the topic or not presenting clinical cases. Additional hand-searching of journals and of the reference lists of selected studies, plus the updated search, yielded seven additional papers. The full-text reports of the remaining 103 articles led to the exclusion of 78 because they did not meet the inclusion criteria ( Table S1 ). Thus, a total of 25 publications were included in the review.

4. Discussion

The present systematic review aimed to investigate the survival rate of PLVs. A total of 433 out of PLVs failed, considering four complications (fracture, debonding, occurrence of secondary caries, need of endodontic treatment) as reasons for failure, and the 10-year CSR was 95.5%. It is important to stress here that just calculating the general failure rate of the prosthesis (the number of failures in relation to the number of placed restorations) without accounting for the time under risk is not an appropriate procedure [9], as there was a great variation in the observational periods of different studies, and even for different restorations in the same study. PLV failure was observed over time and not all participants were observed for the same time; therefore, censoring has occurred. Therefore, all statistics should include time to event methods, namely the methods of survival analysis [34].

The results of the life table analysis should be interpreted with caution. The numbers entering the interval were low and the censored numbers were proportionally high for &#;general failure&#; from year 11, for the outcome &#;fracture&#; from year 10, and for &#;debonding&#; from year 11, reducing confidence of the outcomes [34]. The most recent observations are the least reliable, because of the decreasing number of patients at risk for the event of interest [35].

The definition of failure was an issue for the present review. Differences between studies regarding the complications that were recognized as failures changed the failure rate of some outcomes. The absence of standardized concepts on the definition of failure caused heterogeneity and created difficulties in properly analyzing the failure rate. &#;Failure&#; of PLVs included one, or a combination of complications such as PLV fracture, cracks or chipping, debonding, failure of the marginal integrity, color instability or mismatch, post-operative sensitivity, secondary caries, microleakage, postoperative root canal treatment or endodontic complications, gingival tissue pathological response or periodontal, staining of the luting cement, over-contouring, when the abutment tooth was extracted following a biologic complication, &#;loss of function&#;, &#;when it needed to be replaced&#;, &#;an irreparable problem&#;, &#;clinically unacceptable but repairable&#;, and &#;clinically unacceptable with replacement needed&#;. In some studies, failure was classified as &#;absolute&#; or &#;relative&#; [5,18,22]. In others, failure occurred only in the cases that required replacement of the entire restoration or tooth extraction [28], despite the presence of some biological complications (caries, endodontic treatments, and periodontal interventions) that would be classified as a failure in other studies. Another issue was the occurrence of &#;fractures&#;, &#;cracks&#;, and &#;chipping&#;. Chipping and cracks were not always considered as &#;failure&#; in the studies; in most occurrences these were considered as &#;failure&#; in the cases when the defect was irreparable. Moreover, the criteria for failure was not always described in detail, which can cause divergences and limit the ability to obtain a clear understanding of the overall survival rate of these restorations. That was the reason why we chose to focus of the survival rate in relation to clearly established complications, namely restoration fracture, debonding, occurrence of secondary caries, and post-cementation need of endodontic treatment. For this review, slight marginal defects and slight marginal discolorations were not considered as failures since they have more to do with the appearance of the PLV, and can be easily repolished or repaired.

There are four different main preparation designs for PLVs, namely, window, feathered-edge, palatal-chamfer, and butt joint incisal preparations [36]. The PLV design is believed to play a role in PLV survival, and although most of the designs would be intra-enamel preparations, with usually some minor dentine exposure, an extended PLV design could be associated with larger areas bonded to dentin structure. While bonding to dentin is believed to be weaker than to enamel, and show to a higher risk of microleakage and debonding, because dentin bonding relies on organic components [37]. As bond durability is critical for the longevity of restorations, since degradation can weaken adhesion and lead to gaps between teeth and restorations [38], the preparation design would be an important factor to evaluate in relation to PLV failure. However, we decided not to perform any kind of analysis comparing different preparation designs (except for the presence or not of incisal coverage), as a clear-cut distinction between these four main designs was not always possible: some studies [5,13,14,32] did not provide enough information on this, and even when the information was available, the preparation design was not always standardized among studies. To make matters worse, the nomenclature used for each design was not always the same among studies. Moreover, studies showed a great variation of the extension in which the tooth labial surfaces were reduced, another factor that could have influenced the prevalence of complications.

When it comes to the incisal coverage, the percentage of failures of PLVs without incisal coverage was higher than the percentage of failures of PLVs with incisal coverage. Plain percentage is, however, not the appropriate way to compare failure between the groups. A survival analysis is the most adequate method to do so, but comparing both groups with this type of analysis was not possible, since there was no information on the time-point failure for any of the PLVs without incisal coverage. This finding is not in agreement with the results of a review comparing PLVs with and without incisal coverage [39]; the results of this previous review did not show a statistically significant difference of the survival rates between these two designs. However, the results of the preview review [39] were based on a meta-analysis that included three clinical studies only. Moreover, none of the studies included in this comparison [7,23,31] performed in this previous review [39] provided the precise time-points of failure of the PLVs. Furthermore, the study [39] performed a meta-regression to show that there was no association between survival rate and follow-up time, which does not seem to be an accurate finding. The present review observed that most failures happen within the first years after bonding. Our results also agree with the findings of another review on the subject [40], which observed that preparation design with incisal coverage for PLVs exhibited an increased failure risk compared to those without incisal coverage. The results of this other review [40] were also based on a limited number of included studies; the results of only five clinical studies were included in this analysis.

The present results showed that non-feldspathic PLVs presented a lower failure rate than feldspathic PLVs. This may be related to the weaker properties of feldspathic porcelains in relation to the non-feldspathic ones. The mechanical properties of feldspathic porcelains are low, with low values of flexural strength [41].

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Fracture is believed to be one of the most common causes of PLV absolute failure. One of the reasons for this could be the low ductility of ceramic materials, which is an inherent problem, yielding to crack formation [42]. Moreover, the veneering porcelains may be more susceptible to fracture under mechanical stress due to the absence of a core material [43]. Another factor would be the stress concentrations at the adhesive interface created by the polymerization shrinkage of the luting composite [44]. When the PLV is bonded to a dentin surface with a lower rigidity, the PLVs may be more exposed to stresses during loading, leading to an increased risk of fractures compared to PLVs bonded to enamel [45]. Flexural risk tends to be higher when bonding to a higher extension of dentin, because dentin tends to be more flexible than enamel [43]. This increase in flexural risk would eventually increase the fracture rate.

The aforementioned issues with dentin are also believed to be related to debonding, another one of the most common problems with PLVs. Debonding can also be a result of lack of sufficient adhesion [45], and the used luting cement. The tooth substrate composition may involve a combination of enamel, dentin, and existing composite restoration which may make the adhesion more challenging [45]. High failure rates in PLVs have been associated to largely exposed dentin surfaces [46]. Another study observed that, after 18 months of follow-up, PLVs crossing existing composite restorations showed more failures than the PLVs that were cemented on intact teeth [47]. It was not possible in the present review to properly verify the influence of the extension of dentin in the PLV preparations of the included studies, as this was usually not described in detailed. Besides, it is not always easy to distinguish between the presence of dentin or enamel in the preparation, as this is usually determined visually [45].

According to the results of the present review, the prevalence of secondary caries was not high, with most of the occurrences detected in the long-term follow-up period. This may be explained by the aging of the adhesive resin or the luting cement, or cement wash-out, which may be responsible for minor voids and defects between the prepared tooth and the PLV [6], which could increase the chance of secondary caries. Initial polymerization shrinkage could also be a cause [6], but as this happens immediately on bonding, this would probably cause problems with secondary caries in the early follow-up period. The risk is higher when the preparation extends lingually, making it more difficult to identify such minor defects [45]. When all the margins of the preparation lie on enamel the risk is lower, due to the superior bond of the adhesive in relation to dentin, as aforementioned elsewhere in the text.

The prevalence of endodontic complications as a reason for failure was relatively low in comparison to the three other complications. This complication may be related to the already discussed issues of bonding and the occurrence of undetected secondary caries.

It is believed that bruxism may have some negative impact on the long-term survival of PLVs. The study of Beier et al. [5] conducted a specific analysis concerning this parafunction, and half of the patient population of their study self-reported or were diagnosed as bruxers. Statistical analysis revealed a significantly higher failure rate for PLV restorations in patients who were bruxers. Another study [48] suggested that there is a higher risk of PLV failure in patients with bruxism activity. It is suggested that bruxism may be a risk factor for fractures of ceramics [49], and possibly be one of the causes of an increased prevalence of technical complications in different types of prosthetic rehabilitations [50,51,52].

The results of the present study have to be interpreted with caution because of their limitations. First of all, all confounding factors may have affected the long-term outcomes, and the impact of all these variables on the survival rate of restorations is difficult to estimate if these factors are not identified separately. Second, most of the included studies had a retrospective design, and the nature of a retrospective study inherently results in flaws [53,54]. These problems are manifested by the gaps in information and incomplete records. Third, much of the research in the field is limited by small cohort size and short follow-up periods, which might have led to an underestimation of actual failures in some studies. However, it is hard to define what should be considered a short follow-up period to evaluate PLVs in patients. Fourth, the present review included only studies published in English, with the risk of language bias, which may have some influence on the effect estimates of the outcomes being analyzed [55].

Nowadays, the growing aesthetic demand from patients and the diffusion of biological concepts, such as minimally invasive property and biomimicry, have increasingly popularised the use of minimally invasive aesthetic-functional rehabilitation solutions, such as dental veneers. (1-5)

Dental veneers today are indicated for the treatment of diverse problems such as discolouration, fractures, abrasions, misalignments and shape anomalies and are therefore a therapeutic option with a wide range of uses. (1-5)

The development of exclusively additive veneers

The development of new materials already performing in very limited thicknesses and the improvement of techniques and materials for cementation have considerably reduced the thickness of the preparations and therefore their invasiveness, which helped preserve a greater quantity of dental tissue and provided a path to increasingly minimally invasive dentistry. (1)

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More conservative approaches make it possible to limit mechanical and clinical problems typical of more aggressive preparations (6). The reduced thickness of the prostheses limits internal mechanical stress from bending (7-9), while the less destructive preparation allows to contain the amount of enamel removed. Enamel is a better substrate than dentin for achieving effective adhesion, and thus its preservation turns out to be essential. (10)

Enamel is therefore an extremely important factor. In fact, it has been observed that the preservation of a good quantity of enamel surface and the positioning of the finishing margins of the rehabilitation localised in the thickness of the enamel itself are two fundamental factors for the good prognosis of a ceramic veneer. (11.12)

Following these concepts, we have moved on to increasingly minimally-invasive preparation philosophies, and the preparations of the veneers have gradually become more minimal, up to the creation of exclusively additive veneers, where there is no preparation: these are no-prep veneers.

Advantages of no-prep veneers: the &#;contact lens&#; effect and the reversibility of the treatment

Among the advantages, it should be remembered that, by working in smaller thicknesses, it is possible to obtain a better optical transition between the tooth and the reconstruction, with a &#;contact lens&#; effect. (13.14)

Other advantages of no-prep veneers are:

1. the possibility to completely avoid the provisional phase;
2. the theoretical total reversibility of the treatment, not touching the surface of the teeth in any way &#; even if the removal of a ceramic veneer perfectly adhered to the tooth enamel is a laborious procedure and not difficulty-free.

Disadvantages of no-prep veneers: the complexity of the treatment and overcontours

Among the disadvantages, first we have all the greater global complexity of the treatment, which requires great care during all phases of implementation (particularly in the adhesive step), intraoral finishing and polishing. (15)

No-prep veneers require great skill, e.g. result therefore depends on the professional: it is in fact complex to obtain a satisfactory anatomy and avoid overcontours that could become pigmented over time and give rise to cavity infiltration. (1)

To avoid overcontours, the margins are tapered as much as possible, making the veneers more sensitive to &#;chipping&#; phenomena both during the laboratory phases and during the intraoral clinical phases. In the mouth, it is possible that these phenomena occur both while the veneer is being positioned during the cementation phase and due to the polymerisation contraction of the resin cement. (16)

If the work involves reduced thicknesses, it is also difficult to mask significant dichromatisms.

Since there is no preparation guideline, another important clinical disadvantage concerns the positioning of the veneer on the tooth, which risks not being precise and compromising the aesthetic result, as well as the prognosis of the rehabilitation.

Conclusions

To date, there is no important scientific evidence on this type of minimally invasive rehabilitation.
However, it is always necessary to consider the clinical difficulties, the complexity of production and the limits that are imposed on the clinician by the materials themselves.

References

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1.  Zarone, F., LeoNe, R., Di Mauro, M. I., Ferrari, M., & Sorrentino, R. (). No-preparation ceramic veneers: a systematic review. Journal of Osseointegration, 10(1), 17-22.
2. Zarone F, russo s, sorrentino r. From porcelain-fused-to-metal to zirconia: clinical and experimental considerations. Dent Mater ; 27(1):83-96.
3. Zarone F, Ferrari M, Mangano FG, leone r, sorrentino r. Digitally oriented materials: focus on lithium disilicate ceramics. int J Dent ; 2:.
4. Skyllouriotis Al, yamamoto hl, Nathanson D. Masking properties of ceramics for veneer restorations. J Prosthet Dent ; pii: s-(16)-1.
5. Höland w, schweiger M, watzke r, Peschke A, Kappert h. Ceramics as biomaterials for dental restoration. Expert rev Med Devices ; 5(6):729-45.
6. Vanlıoğlu BA, Kulak-Özkan y. Minimally invasive veneers: current state of the art. Clin Cosmet investig Dent ; 6:101-7.
7. Zarone F, Epifania E, leone G, sorrentino r, Ferrari M. Dynamometric assessment of the mechanical resistance of porcelain veneers related to tooth preparation: a comparison between two techniques. J Prosthet Dent ; 95(5):354-63.
8. Sorrentino r, Apicella D, riccio C, Gherlone E, Zarone F, Aversa r, Garcia- Godoy F, Ferrari M, Apicella A. Nonlinear visco-elastic finite element analysis of different porcelain veneers configuration. J Biomed Mater res B Appl Biomater ; 91(2):727-36.
9. Perillo l, sorrentino r, Apicella D, Quaranta A, Gherlone E, Zarone F, Ferrari M, Aversa r, Apicella A. Nonlinear visco-elastic finite element analysis of porcelain veneers: a submodelling approach to strain and stress distributions in adhesive and resin cement. J Adhes Dent ; 12(5):403-13.
10. Ferrari M, Patroni s, Balleri P. Measurement of enamel thickness in relation to reduction for etched laminate veneers. int J Periodontics restorative Dent ; 12(5):407-13.
11. Gurel G, sesma N, Calamita MA, Coachman C, Morimoto s. influence of enamel preservation on failure rates of porcelain laminate veneers. int J Periodontics restorative Dent ; 33(1):31-9.
12. Cötert hs, Dündar M, Oztürk B. The effect of various preparation designs on the survival of porcelain laminate veneers. J Adhes Dent ; 11(5):405-11.
13. Zarone F, Apicella D, Sorrentino R, Ferro V, Aversa R, Apicella A. Influence of tooth preparation design on the stress distribution in maxillary central incisors restored by means of alumina porcelain veneers: A 3D finite element analysis. Dent Mater ; 21:-.
14. Magne P, Hanna J, Magne M. The case for moderate &#;guided prep&#; indirect porcelain veneers in the anterior dentition. The pendulum of porcelain veneer preparations: from almost no-prep to over-prep to no-prep. Eur J
15. Wells D. Low-risk dentistry using additive-only (&#;no-prep&#;) porcelain veneers. Compend Contin Educ Dent ; 32(5):50-5.
16. Morimoto S, Albanesi RB, Sesma N, Agra CM, Braga MM. Main Clinical Outcomes of Feldspathic Porcelain and Glass-Ceramic Laminate Veneers: A Systematic Review and Meta-Analysis of Survival and Complication Rates. Int J Prosthodont ; 29(1):38-49.