Clinical maneuvers comprising the preparation of the dental substrate, the construction and adjustment of dental ceramics and their long-term performance

Manobras clínicas compreendidas no preparo do substrato dental, na construção e ajustes das cerâmicas dentais e o seu desempenho a longo prazo

ABSTRACT

Aesthetic restorative materials, especially dental ceramics, are one of the most requested materials in oral rehabilitation. The success of dental ceramics, in general, is dependent on factors such as their physical properties, the manufacturing process of indirect work and the clinical procedures included in their adjustments and cementation. Understanding the conditions related to such materials and the professional’s attitude towards the handling of ceramic works contributes to their proper performance. It is worth mentioning the issue related to the oral environment, a condition that opposes the success of such materials, as it is an environment subjected to loads of varying intensity and direction. A humid environment, constantly subjected to thermal changes, changes in pH, and where longevity of such materials is expected to be considered friable. This paper aims to review the aspects related to the evolution and performance of current ceramic systems. At the same time, it proposes a reflection of the clinical and laboratory maneuvers commonly involved in the construction, preparation and adjustment of pure ceramic prosthetic pieces.

Indexing terms
Ceramics; Dental prosthesis retention; Metal ceramic alloys

RESUMO

Materiais restauradores estéticos, especialmente as cerâmicas dentais são um dos materiais mais requisitados nas reabilitações orais. O sucesso das cerâmicas odontológicas, de modo geral, está na dependência de fatores tais como, suas propriedades físicas, o processo de fabricação dos trabalhos indiretos e os procedimentos clínicos compreendidos nos ajustes e cimentação dos mesmos. A compreensão das condições relativas a tais materiais e a postura do profissional frente ao manuseio dos trabalhos cerâmicos colaboram para o seu adequado desempenho. Vale ressaltar a questão relacionada ao ambiente oral, condição esta que contrapõe o sucesso de tais materiais, por se tratar de um ambiente submetido a cargas de intensidade e direção variadas. Um ambiente úmido, constantemente submetido a mudanças térmicas, mudanças de pH, e de onde se espera uma longevidade de tais materiais, por sua vez, considerados como friáveis. Este trabalho objetiva revisar os aspectos relativos à evolução e desempenho dos atuais sistemas cerâmicos. Ao mesmo tempo, propõe uma reflexão das manobras clínicas e laboratoriais comumente envolvidas na construção, preparo e ajustes das peças protéticas em cerâmica pura.

Termos de indexação
Cerâmicas; Retenção em Prótese Dentária; Ligas metal-cerâmica

INTRODUCTION

All-ceramic restorations have only become viable since the evolution of ceramic systems, both chemically, mechanically and optically [¹,²].

Because it involves a meticulous and complex manufacturing process, control of the ideal properties is meticulous and the resulting clinical performance must be considered a factor that depends not only on the choice of material, but also on correct handling by the clinician and laboratory technician. For this reason, the longevity of ceramic restorations is the subject of much discussion [³,⁴].

The longevity of all-ceramic restorations is known to be lower in molar and premolar regions (84.4%) compared to anterior regions (94.5%) for the same ceramic system [⁴].

It is worth highlighting the issue related to the oral environment, where a minimum longevity is expected of such materials, which are considered to be friable. Cyclical loads in humid environments, such as those related to the oral cavity, favor the propagation of cracks, even when stress levels considered below critical levels are present [⁵].

This work aims to review aspects relating to the evolution and performance of current ceramic systems. At the same time, it proposes a reflection on the clinical and laboratory maneuvers commonly involved in the construction, preparation and adjustment of all-ceramic prosthetic parts, in order to contribute to the longevity of ceramic restorations.

DISCUSSION

The clinical performance of ceramic restorations depends on many factors, from the material selected to the correct handling by the laboratory technician and the dental surgeon responsible for final adjustments and cementation [³,⁶]. If handled improperly, they can negatively influence the strength of such restorations [⁷]. The longevity of ceramic restorations is strongly related to the intensity of the damage applied to their surface. Also, knowing their properties in order to indicate the correct system for each clinical condition is another point to be taken into account when adding up the final strength of indirect work (Chart 1).

Chart 1
Main ceramic materials currently available, mechanical properties, clinical indications, sensitivity to acid etching and etching time.

Ceramic materials	Mechanical resistan	Clinical indications	Acid etching sensitivity/etching time
Fedspatial ceramics	120 MPa	Anterior crowns, Veneers, Minimally Invasive Laminates, Inlay and Onlay	Sensitive Acid (1 minute)
Leucite-reinforced ceramics	160 – 180 MPa	Anterior crowns, Veneers, Minimally Invasive Laminates, Inlay and Onlay	Sensitive Acid (1 minute)
Lithium Disilicate Reinforced Ceramics	350 MPa	Anterior crowns, Posterior crowns up to premolars, Conventional anterior PPF, Adhesive anterior PPF, Veneers, minimally invasive laminates, Inlay and Onlay	Sensitive Acid (20 seconds)
Alumina Reinforced Ceramics	500 – 600 MPa		Acid Resistant
Zirconia	850 – 1200 Mpa	Anterior and posterior crowns, anterior and posterior PPF, implant abutments	Acid Resistant

It is also worth mentioning the conditions of the oral environment in which ceramic restorations live.

Dental ceramics are known to be friable materials and susceptible to slow crack growth [¹,⁸]. From a clinical point of view, neither the patient nor the professional is able to identify whether a crack has started or propagated in a given area until the restoration actually fails. For this reason, an initial crack does not appear to be the cause of failure in ceramic restorations, since the need to replace the restoration does not occur at that early stage [⁹].

Even under low masticatory loads, especially in a humid environment, which is the case in the oral cavity, a crack is prone to propagation, thus reducing the strength of ceramic restorations [⁵]. Very commonly used for infrastructure, lithium disilicate-based ceramics (IPS Empress 2) are susceptible to this factor. In the case of zirconia, the slow growth of cracks is due to the fact that water depletes yttrium, which is responsible for increasing its hardness [¹⁰].

Exposure to the acidic components of a diet, even though ceramics are considered to be a stable material, favors slow crack growth. The results of some studies suggest, for this reason, that dental ceramics may not actually be chemically stable, as previously attested [¹¹,¹²].

The basic materials therefore used for the infrastructure of all-ceramic crowns available so far are lithium disilicate and glass-infiltrated ceramics (alumina and zirconia). Zirconia (Y-TZP yttria-stabilized polycrystalline tetragonal zirconia ceramic) was introduced in an attempt to eliminate most of the fractures seen in restorations made with these other ceramic materials.

It is a material with high mechanical strength, around 870 MPa, and for this reason it has become the material of choice for the infrastructure of ceramic prostheses and posterior fixed partial dentures (FPDs) [¹³-¹⁷]. Failures in restorations with zirconia infrastructure are related to fractures in the veneering porcelain and is considered the main cause of failure of these materials. These fractures often originate in the region of wear veneers [¹⁸].

During the laboratory process, among other things, residual stresses related to the incompatibility between the coefficients of thermal expansion of the infrastructure and veneering materials are responsible for the appearance of cracks. As a result, there is an increased likelihood of chips appearing in the roof tiles. Cracking episodes that can culminate in fractures in the roofing material irreversibly compromise the aesthetics of previous work. In the case of monolithic works, cracks and consequent fractures are much less likely. On the other hand, due to the high aesthetic demands, all-ceramic anterior restorations are commonly veneered, which favors the failure rate of the veneering ceramic [¹⁹].

The quality of the preparation of the dental substrate is another factor that contributes to the longevity of ceramic work. Its dimensions, wall configurations and internal and external angles, the design of the cervical end and the finish of the cavity margins determine the quality of the copy, whether it is made from rubber materials (conventional method) or using the scanning technique (CAD/CAM method) [²⁰,²¹]. Inadequate marginal adaptation favors the accumulation of bacterial plaque, thus compromising the longevity of indirect work [²²,²³]. In the case of the scanning technique, capturing details related to a poorly finished preparation is even more compromised due to the limitations related to the scanner’s light [²⁴]. For this reason, extra attention should be paid to preparations that will have their respective prostheses made digitally.

When one takes into account the method of obtaining the ceramic work, whether conventional or digital, the longevity rate of both is similar. On average, 91.0% for the CAD/CAM technique and 93.3% for the conventional production method [⁴]. However, rubber materials are able to copy details related to, for example, sharp internal angles, subgingival margins when the gingival tissue is removed and unfinished walls. On the other hand, the scanner light and the milling machine have limitations with regard to these aspects [²⁵-²⁷].

The justification for rounded internal angles for ceramic work does not only apply to work whose restorations will be produced by the CAD/CAM method. Sharp angles increase the stress concentration at the edge of the ceramic material, making these sites more prone to fracture initiation [²⁸].

Another important step in the tooth preparation technique, especially for ceramic crowns, is occlusal reduction. This reduction must be anatomical, so that both the infrastructure material and the veneering material have uniform thicknesses. This condition minimizes the occurrence of chips and fractures in transition areas of different veneer thicknesses, when the veneer is not supported by the infrastructure ceramic [²⁸].

The above confirms the importance of the cavity preparation step in the clinical performance of ceramic restorations. Once the construction of the prosthetic piece is complete, it is time to adapt it and make the necessary proximal and occlusal adjustments.

Modifying the internal shape of the restoration to correct irregularities that may be interfering with the adaptation of the piece is not expected in the case of a well-conducted preparation, let alone ideal. A small occlusal adjustment is not uncommon. However, if this adjustment is insufficient or unfinished, it becomes a site for crack initiation, which drastically reduces the strength of restorations. Particle abrasion compromises the surface of such materials, promoting the formation of deep scratches and grain loss [⁷]. Similarly, if the sandblasting technique is used prior to cementation, prolonged conditioning of the ceramic substrate and other inappropriate clinical maneuvers, the same problem will arise [²⁷-²⁸].

CONCLUSION

Knowing, therefore, the influence of the clinical and laboratory procedures imposed on these materials, it can be concluded that increasing their strength alone may not be enough to improve the clinical performance of ceramic restorations. In view of this, it is important for both the laboratory technician and the clinician to be aware of the conditions related to the correct handling of ceramic materials, the geometry of the preparations and the final stages associated with the proximal, occlusal and cementation adjustment procedures.

• How to cite this article
  Silva LD, Silva NRFA, Silveira RR, Abuquerque RC, Martins AV. Clinical maneuvers comprising the preparation of the dental substrate, the construction and adjustment of dental ceramics and their long-term performance. RGO, Rev Gaúch Odontol. 2025;73:e20250013. http://dx.doi.org/10.1590/1981-86372025001320240066

REFERENCES

• ¹ Anusavice KJ, Shen C, Rawls HR. Materiais dentários de Phillips. 12a. ed. Philadelphia: Saunders Elsevier; 2018.
• ² Peumans M, Meerbeek BV, Lambrechts P, Vanherle G. Porcelain veneers: a review of the literature. J Dent. 2000;28:163-77.
• ³ Petra C, Guess PC, Schultheis S, Bonfante EA, Coelho PG, Ferencz JL, et al. All-Ceramic Systems: Laboratory and Clinical Performance. Dent Clin. 2011;55:333-52. http:// dx.doi.org/10.1016/j.cden.2011.01.005
  » https://doi.org/10.1016/j.cden.2011.01.005
• ⁴ Pjetursson BE, Sailer I, Zwahlen M, Hammerle CHF. A systematic review of the survival and complication rates of all-ceramic and metal-ceramic reconstructions after an observation period of at least 3 years. Part I. Single crowns. Clin Oral Implants Res. 2007;18:73-85. http://dx.doi.org/10.1111/j.1600-0501.2007.01467.x
  » https://doi.org/10.1111/j.1600-0501.2007.01467.x
• ⁵ Marocho SMS, Studart AR, Bottino MA, Bona AD. Mechanical strength and subcritical crack growth under wet cyclic loading of glass-infiltrated dental ceramics. Dent Mater. 2010;26:483-90. http://dx.doi.org/10.1016/j.dental.2010.01.007
  » https://doi.org/10.1016/j.dental.2010.01.007
• ⁶ Munck J, Landuyt KV, Peumans M, Poitevin A, Lambrechts P, Braem M, et al. A critical review of the durability of adhesion to tooth tissue: methods and results. J Dent Res. 2005;84(2):118-32. http://dx.doi.org/10.1177/154405910508400204
  » https://doi.org/10.1177/154405910508400204
• ⁷ Wang H, Aboushelib MN, Feilzer AJ. Strength influencing variables on CAD/CAM zirconia frameworks. Dent Mater. 2008;24:633-8. http://dx.doi.org/10.1016/j.dental.2007.06.030
  » https://doi.org/10.1016/j.dental.2007.06.030
• ⁸ Bona AD, Anusavice KJ. Microstructure, composition, and etching topography of dental ceramics. Int J Prosthodont. 2002;15:159-67.
• ⁹ Zhang Y, Lawn BR, Malament KA, Thompson VP, Rekow ED. Damage accumulation and fatigue life of particle-abraded ceramics. Int J Prosthodont. 2006;19:442-8.
• ¹⁰ Taskonak B, Yan J, Mecholsky JJ Jr, Sertgoz A, KoÇak A. Fractographic analyses of zirconia- based fixed partial dentures. Dent Mater. 2008;24:1077-82. https://doi.org/10.1016/j.dental.2007.12.006
  » https://doi.org/10.1016/j.dental.2007.12.006
• ¹¹ Curran P, Lorente MC, Wiskott HWA, Durual S, Scherrer SS.Grinding damage assessment for CAD/CAM restorative materials. Dent Mater. 2017;33:294-308. https://doi.org/10.1016/j.dental.2016.12.004
  » https://doi.org/10.1016/j.dental.2016.12.004
• ¹² Rosa V, Yoshimura HN, Pinto MM, Fredericci C, Cesar PF. Effect of ion exchange on strength and slow crack growth of a dental porcelain. Dent Mater. 2009;25:736-43. http://dx.doi.org/10.1016/j.dental.2008.12.009
  » https://doi.org/10.1016/j.dental.2008.12.009
• ¹³ Bona AD, Kelly JR. The clinical success of all-ceramic restorations. J Am Dent Assoc. 2008;139:8S-13S. doi: https://doi.org/10.14219/jada.archive.2008.0361
  » https://doi.org/10.14219/jada.archive.2008.0361
• ¹⁴ Raigrodski AJ, Chiche GJ. All-ceramic fixed partial dentures. Part I: in vitro studies. J Esthet Restor Dent. 2002;14:188-91. https://doi.org/10.1111/j.1708-8240.2002.tb00518.x
  » https://doi.org/10.1111/j.1708-8240.2002.tb00518.x
• ¹⁵ Raigrodski AJ, Chiche GJ, Potiket N, Hochstedler JL,Mohamed SE, Billiot S, et al. The efficacy of posterior three-unit zirconium-oxide-based ceramic fixed partial dental prostheses: a prospective clinical pilot study. J Prosthet Dent. 2006;96:237-44. https://doi.org/10.1016/j.prosdent.2006.08.010
  » https://doi.org/10.1016/j.prosdent.2006.08.010
• ¹⁶ Raigrodski AJ, Chiche GJ, Swift EJ Jr. All-ceramic fixed partial dentures. Part III: clinical studies. J Esthet Restor Dent. 2002;14,313-9. http://dx.doi.org/10.1111/j. 1708-8240.2002.tb00527.x
  » https://doi.org/10.1111/j. 1708-8240.2002.tb00527.x
• ¹⁷ Sailer I, Feher A, Filser F, Gauckler LJ, Lüthy H, Hämmerle CHF. Five-year clinical results of zirconia frameworks for posterior fixed partial dentures. Int J Prosthodont. 2007;20:383-8.
• ¹⁸ Etman MK, Woolford MJ (2010). Three-year clinical evaluation of two ceramic crown systems: a preliminary study. J Prosthet Dent. 2020;103(2):80-90.
• ¹⁹ Heffernan MJ, Aquilino AS, Arnold AMD, Haselton DR, Stanford CM, Vargas MA. Relative translucency of six all-ceramic systems. Part I: core materials. J Prosthet Dent. 2002;88:4-9.
• ²⁰ Beuer F, Schweiger J, Edelhoff D. Digital dentistry: an overview of recent developments for CAD/CAM generated restorations. Braz Dent J. 2008;204:505-11. http://dx.doi.org/10.1038/sj.bdj.2008.350
  » https://doi.org/10.1038/sj.bdj.2008.350
• ²¹ Beuer F, Edelhoff D, Gernet W, Sorensen JA. Three-year clinical prospective evaluation of zirconia-based posterior fixed dental prostheses (FDPs). Clin Oral Investig. 2009;13:445-51.
• ²² Feitosa SA, Corazza PH, Cesar PF, Bottino MA, Valandro LF. Pressable feldspathic inlays in premolars: effect of cementation strategy and mechanical cycling on the adhesive bond between dentin and restoration. J Adhes. Dent 2014;16:147-54. http://dx.doi.org/10.3290/j.jad.a30555
  » https://doi.org/10.3290/j.jad.a30555
• ²³ Chan DCN, Chung AK-H, Haines J, Yau EH-T, Kuo C-C. The accuracy of optical scanning: influence of convergence and die preparation. Oper Dent. 2011;36(5):486-491. http://dx.doi.org/10.2341/10-067-L
  » https://doi.org/10.2341/10-067-L
• ²⁴ Pradíes G. Zarauz C, Valverde A, Ferreiroa A, Rus FM. Clinical evoluation comparing the fet of all-ceramic crowns obtaind from silicone and digital intraoral impressions based on wavorfront sampling technology. J Dent. 2014;1:1-8. http://dx.doi.org/10.1016/j.jdent.2014.12.007
  » https://doi.org/10.1016/j.jdent.2014.12.007
• ²⁵ Steyern PVV, Carlson P, Nilner K. All-ceramic fixed partial dentures designed according to the DC-Zirkon® technique. A- 2-year clinical study. J Oral Rehabil. 2005;32:180-7. https://doi.org/10.1111/j.1365-2842.2004.01437.x
  » https://doi.org/10.1111/j.1365-2842.2004.01437.x
• ²⁶ Jalalian E, Atashkas B, Rostami R. The effect of preparation design on the fracture resistence of zirconia crown copings (Computer Associated Design/Computer Associated Machine, CAD/CAM System). J Dent. 2011;8:123-9.
• ²⁷ Bonfante EA, Rafferty B, Zavanelli RA, Silva NRFA, Rekow ED, Thompson VP, et al. Thermal/mechanical simulation and laboratory fatigue testing of an alternative yttria tetragonal zirconia polycrystal core-veneer all-ceramic layered crown design. Eur J Oral Sci. 2010;118:202-9. https://doi.org/10.1111/j.1600-0722.2010.00724.x
  » https://doi.org/10.1111/j.1600-0722.2010.00724.x
• ²⁸ Bona AD, Noort RV. Ceramic surface preparations for resin bonding. Am J Dent 1998;11:276-80.

Edited by

• Assistant editor:
  Luciana Butini Oliveira

Publication Dates

• Publication in this collection
  15 Aug 2025
• Date of issue
  2025

History

• Received
  10 Oct 2024
• Accepted
  13 Dec 2024