New materials have made possible greater results in esthetic dentistry. Consider the evolution of composite materials, brought about by manufacturers’ improvements to their optical characteristics. New ceramic materials, used with pressed or computer-assisted techniques, have considerably enhanced our color choices and the results that can be achieved.Every tooth thrives on reflected light as it is incorporat- ed in its natural surroundings—this being the oral cavity— in a well-balanced and discreet manner. The effect of color depth that is perceived when we look at teeth can vary; this is due to the translucence of natural enamel, which gives each tooth its delicate coloring. The translucent enamel tones down the strong color of the dentin under- neath, creating the final color by overlapping chromatic shades that have different densities and giving the tooth its three-dimensionality.
The dental team needs to study the dental structures and be able to match them with the appropriate type of restorative material3,4 to obtain the best esthetic and func- tional result for the patient. With an understanding of the handling properties of each material, combined with care- ful planning, assessment, and color analysis, the team can choose from the wide range of restorative materials pro- duced by the various manufacturers and match them ac- cording to each clinical case.
ROLES OF DENTAL STRUCTURES
Tooth enamel has two important roles: (1) to mechanically crush and grind food and (2) to provide protection for the dentin underneath it. One of the roles of dentin is to ab- sorb mastication force, which it does thanks to its high resistance to compression.
The material used to replicate or substitute tooth enamel needs to have a hardness value equivalent to or higher than the enamel itself, along with wear and abrasion resis- tance. In the case of dentin, the best option is to use mate- rials that offer the same or similar mechanical properties, like elasticity (elastic modulus).
Studies that assess compression by force only take into consideration mechanical characteristics of materials and dental tissue. There have been no in vitro tests that can simulate complex mechanisms and situations that regulate function. As always, literature and protocols are based on scientific evidence, and facts have to be taken into consid- eration to guide us to the correct choice.
PROPERTIES AND CHARACTERISTICS OF RESTORATIVE MATERIALS
Composite Resins
Adhesive dentistry today can benefit from a series of test- ed composite materials that provide great esthetic poten- tial. Choosing an option that has the lowest price tag and offers simplified techniques for enamel substitutes is cer- tainly appealing. The gap between direct and indirect solu- tions has been narrowed thanks to CAD/CAM techniques, through which composite veneers can be obtained using a semi-indirect approach to achieve optimum results.
The brightness and texture of the surfaces of compos- ite restorations are still far from the standards that can be reached with ceramic materials; this is due to the nature of the material itself and its higher abrasiveness (in the long term). The same can be said with regard to inner effects of absorbency and dispersion of light to simulate opales- cence of the enamel, which are far from those that can be achieved with glass-ceramic.
Several clinical studies and their follow-up results after 3 years have demonstrated that composite veneers show six times greater wear and abrasion than ceramic veneers. This is an important issue to consider, especially for clini- cians treating young adult patients with high esthetic ex- pectations.
Another point to consider is the material’s resistance to fracture, especially for patients who exhibit a high stress profile (eg, bruxism). From several studies we deduce that the fracture resistance of composites is under 2.0 MPa/ mm2, three times less than that of reinforced ceramic ma- terials.
An in-depth study by Ferraris and Conti11 highlights a very strict and meticulous protocol regarding the finishing and polishing of composite materials for reconstructions to prevent the formation of biofilm, which is responsible for the growth of bacterial colonies in the oral cavity.
Manufacturers of composite materials will likely make significant positive changes in coming years. When using composite resins for esthetic cases, we should keep in mind that some adjustments can be made in the future to compensate for deterioration and color changes due to plaque.
Ceramic Materials
The continuous advances in ceramic materials today have widened the options, providing the possibility to achieve a highly esthetic result in challenging cases as well as spe- cific multidisciplinary treatments (Fig 1). The literature is replete with studies that highly recommend ceramic mate- rials for achieving esthetic results in anterior teeth.
Other considerations for using ceramic materials are their optimum compatibility within the oral cavity, placing them in the category of biologically stable,20 and their high percentage of success over time, which has been shown to be approximately 93% at 10 years and from 91% to 94% at 12 years.21,22
Ceramic materials made from feldspar or glass-ceramic reinforced with leucite crystals or fluorapatite can be syn- thesized on refractory models (stumps) or platinum sheets with the Geller Dental Arch (the Geller model), taking ad- vantage of the translucence of the material.23 The best re- sult is achieved when, along with their individual abilities, clinician and technician work together toward the common goal.
The special nature of the material promotes highly es- thetic results, with thin ceramic layers up to 0.5 mm with or without enamel preparation. Unfortunately, its weakness is fracture resistance on applied force; with an elastic modu- lus between 50 and 120 MPa, ceramics are classified as a fragile material.25 The brittleness of the ceramic material has to be taken into consideration before the luting phase of the restorations. After luting, the brittleness is no longer relevant.
The even distribution of crystals (leucite, fluorapatite, etc) within the glass core changes the mechanical proper- ties of ceramics, making them more resistant to fracture. As the size of the crystal decreases, the material becomes more resistant.26 Ceramics reinforced with lithium disili- cate, with an average distribution of 70% lithium disilicate crystals in the glass material, are even more resistant to fracture owing to higher flexural resistance values.
Glass-ceramic cores can be obtained with several de- grees of translucency and opacity, allowing control of the value of the veneers from the core itself. Any defects in shape or enamel discoloration can be corrected as well. The use of ceramic layers with a lithium disilicate core is fundamental to obtain a satisfactory result, especially in anterior teeth.
The computer-aided revolution (CAD/CAM) has set a standard in production processes, with many benefits such as fewer internal flaws in milled materials.28,29 It is possible to mill ceramic blocks with matte or translucent core mate- rial, applying ceramic layers until the desired color and shape are achieved (Fig 2).
CASE PRESENTATION
A male patient, 18 years of age, presented for a consulta- tion in June 2013 (with Dr Carlo Ghezzi). The radiographs and clinical examination showed a deep bite greater than 60 degrees. Clinically, the patient presented a deep bite that had caused premature abrasion and severe wear of the maxillary and mandibular anterior teeth (Figs 3a to 3c). Upon diagnosis, a combined orthodontic/prosthodontic treatment was deemed necessary to repair the esthetics and function of the compromised teeth.
Orthodontic Treatment
The orthodontic diagnosis showed a Class II basal maloc- clusion, retracted mandible, misalignment of the maxillary incisors, severe wear of the mandibular incisors, and asym- metric wear of the maxillary anterior teeth due to the deep bite (parafunction) over time. The patient’s face had a nor- mal appearance, with the slight retraction of the mandible resulting in a convex profile (Figs 4a and 4b).
The orthodontic treatment plan included anterior torque correction and correction of the Class II malocclusion and of the deep bite (Figs 5a and 5b).
In October 2013, the orthodontic therapy began with temporary reconstruction of the most damaged teeth in order to position the orthodontic brackets. The therapy in- cluded the use of passive self-bonding materials due to their high torque resistance, strategic positioning of self- ligating brackets, and the selection of proper torque value for anterior teeth brackets. The strategic positioning of the same brackets was fundamental for correction of the mal- occlusion.
During treatment, while following protocols, certain cor- rections were needed to guarantee the end result (Figs 6a and 6b). After the Cu-Ni-Ti arch sequencing, the dental class was defined with metal archwires and 4.5-oz Class II elastics. Then the shape of the dental arches was defined with purple titanium molybdenum–alloy archwires, leaving the necessary space for the prosthodontist to restore the anatomical function and integrity of the anterior teeth. The orthodontic treatment was completed in October 2016 (Figs 7a to 7c).
Prosthodontic Treatment
In November 2016, six mandibular and four maxillary ante- rior teeth were prepared (by Dr Alessandro Conti) using a microscope (Zeiss Opmi Pro Ergo) with a minimally invasive approach and with a single retraction cord (Fig 8). The pro- tocol, based on the teachings of Dr Domenico Massironi,30 includes limited removal of tissue, preferably only enamel, and immediate hybridization of exposed dentin if neces- sary. The preparation of each tooth was made with the mock-up in place and was crosschecked with the silicone index. By this way it was possible to maintain a precise thickness.
For immediate dentin sealing, a 4th-generation adhe- sive (Total Tech 3 layers, Ceys) was used. Etching was done with 37% phosphoric acid (on the dentin for 10 to 15 seconds). After rinsing the etched surface with copious water and compressed air for at least 45 to 60 seconds, a 0.2% solution of chlorhexidine digluconate was applied for 1 minute (this inhibits the metalloproteinase present in the dentinal tubules). The dentin was dried without dehydrat- ing. A generous layer of primer was applied and kept in place for at least 60 seconds. It was dried completely and a thin layer of bonding agent was applied and then poly- merized for 60 seconds. Glycerin gel was applied for the final polymerization.
The single retraction cord (Gingi Aid 00) was put in place to deflect and control exposure of tissue (Figs 9a and 9b). After the positioning of the finishing line, two impressions were made using polyether impression material (Permadyne, 3M ESPE) single-application compound mix (Figs 10a and 10b).
Laboratory Phases
The development of the case started with a wax-up by the lab, as requested by the dentist, and then proceeded with the mock-up on the patient for reconstruction of the teeth. The impressions were cast in white extra-hard plaster (GC Fujirock EP, GC Europe). Once the cast models had been obtained (Figs 11a to 11c), white cosmetic wax was applied with special care given to the details that will guide the veneers.
The mock-up was made with a transparent silicone index filled with a dual composite (Protemp, 3M ESPE), in order to assess the esthetics (Figs 12 to 15).
After assessment of the mock-up and approval by the patient, the teeth were prepared as described previously, and the polyether impressions (Permadyne, ESPE) were sent to the lab for fabrication of the veneers.
Two master models were created for each arch. The first were created using the Zeiser technique (Zeiser Sockel-platten, Zeiser Dentalgeräte GmbH), sectioned with remov- able stumps. They were defined on the finishing line, mounting and setting on a dental articulator with dynamic facebow. Finally, the milled glass-ceramic cores were checked and arranged under the microscope with great precision (Stemi 1000, Zeiss) (Fig 16). The second models were made with polyurethane resin (Exakto-Form, Bre- dent), uncut to preserve the morphology of the gingival line, for completing the veneers and to be able to docu- ment the process and photograph the finished mold.
As always, the correct choice of core material is impor- tant to achieve the desired esthetic result. For this case, LT A1 (Ivoclar Vivadent) was used to ensure good passage of light and increase the value of luminosity. The lithium disilicate guaranteed more flexural resistance in this orth- odontic-prosthodontic combined therapy with a change of vertical dimension as well as adjustment to canine and in- cisal guidance. The material ensured a good longevity of the restorations.
Some core tests between the other cores and the exist- ing teeth were made on the patient for precision and cor- rect light balance. This phase guided the team to evaluate the patient’s new correct vertical alignment and functional guidance.
Two composite functional guides were made in the maxillary canine lingual area to achieve the best lateral guidance movement in this new position. Specific on-point information was required to bring back the patient to the centric position of the new vertical dimension of occlusion (Figs 17a to 17e). It is known that the first 2 to 3 mm of lateral guidance movement are important to avoid interfer- ence in the posterior area and to obtain a correct dynamic of function.
The core building of the veneers was completely digital, with the milling of the block of lithium disilicate in LT A1 color. The milling parameters for the cores were set at 0.4 mm, with five continuous axes and water cooling. Crystal- lization of these cores occurred in the heating unit (oven) at 840˚C. The time and temperature settings were estab- lished by the manufacturers of the materials.
The desired outcome was light-colored and natural- looking teeth that matched the texture of the surrounding teeth and young age of the patient (Figs 18 and 19).
The layering technique included application of Power Dentin (Ivoclar Vivadent) on the core masses and A1 color with a 20% addition of Dentin 1C desaturated at 50% with Neutral in the incisal third area to increase the translu- cence and obtain a wider passage of light. During the building of the tooth, light-absorbing masses31 were added also in the incisal third to recreate the opalescence and the light effect that is normally present at the patient’s age. All of this was done without losing control of the shape of the veneers (Figs 20a to 20d).
In the second bake of the ceramic, a small amount of Matte Orange Dentin was added in the proximal area to stop light there. The final enamel filter with neutral mass refinishes the shape and tones down the opalescence of the absorption masses.
In the final step, diamond burs cooled by water were used to achieve the desired texture, making grooves of different sizes for better light refraction.23,32 In the final baking phase, a thin glaze coating was applied, and the structure was polished with felt pads and diamond paste (Figs 21 to 24).
Luting Phase
The luting phase is of most importance to ensure a good prognosis over time. The luting agent bonds and stabilizes the two surfaces. To make this bond last, the clinician must follow a rigid processing protocol and must choose the correct type of luting agent based on its mechanical prop- erties and those of the restorations.
There are many texts explaining in detail how the proce- dure must be carried out correctly to achieve a good luting result.34 For this case, a 4th-generation total-etch adhesive (Optibond FL, Kerr) was used with microhybrid composite as the luting agent, heated to 52°C. A rubber dam was used for isolation of each tooth during the luting phase. All restorations were luted individually.
With constant pressure on the restoration, the excess luting agent was removed. Once all excess was removed and the restoration position was verified as correct, it was polymerized for 90 seconds on each aspect (buccal, incisal, palatal). The final polymerization was done with glycerin gel and the edges were cleaned with a curved blade. The same procedure was then carried out on the next tooth (Figs 25 to 32).
CONCLUSION
Careful planning, preparation of teeth with a minimally in- vasive approach, use of a surgical microscope for preci- sion, and the correct choice of materials for both restoration and luting are crucial to assure a successful and long-term restorative outcome.
Ceramic veneers that are adhesively luted and limited to the enamel represent the gold standard in cases requiring minimal correction to the shape and color of teeth and a conservative solution for preserving enamel.
Lithium disilicate glass-ceramic veneers are highly rec- ommended in cases of combined orthodontic and prosth- odontic therapy. Due to its mechanical properties, lithium disilicate provides good longevity for restorations in which there has been a change of vertical dimension and func- tional guidance.
Also requisite to achieve success is the dentist’s trust in the ability of each member of the team, especially the den- tal technician. This will go a long way in promoting excel- lent results for the patient (Figs 33 to 39).
The dental team needs to study the dental structures and be able to match them with the appropriate type of restorative material3,4 to obtain the best esthetic and func- tional result for the patient. With an understanding of the handling properties of each material, combined with care- ful planning, assessment, and color analysis, the team can choose from the wide range of restorative materials pro- duced by the various manufacturers and match them ac- cording to each clinical case.
ROLES OF DENTAL STRUCTURES
Tooth enamel has two important roles: (1) to mechanically crush and grind food and (2) to provide protection for the dentin underneath it. One of the roles of dentin is to ab- sorb mastication force, which it does thanks to its high resistance to compression.
The material used to replicate or substitute tooth enamel needs to have a hardness value equivalent to or higher than the enamel itself, along with wear and abrasion resis- tance. In the case of dentin, the best option is to use mate- rials that offer the same or similar mechanical properties, like elasticity (elastic modulus).
Studies that assess compression by force only take into consideration mechanical characteristics of materials and dental tissue. There have been no in vitro tests that can simulate complex mechanisms and situations that regulate function. As always, literature and protocols are based on scientific evidence, and facts have to be taken into consid- eration to guide us to the correct choice.
PROPERTIES AND CHARACTERISTICS OF RESTORATIVE MATERIALS
Composite Resins
Adhesive dentistry today can benefit from a series of test- ed composite materials that provide great esthetic poten- tial. Choosing an option that has the lowest price tag and offers simplified techniques for enamel substitutes is cer- tainly appealing. The gap between direct and indirect solu- tions has been narrowed thanks to CAD/CAM techniques, through which composite veneers can be obtained using a semi-indirect approach to achieve optimum results.
The brightness and texture of the surfaces of compos- ite restorations are still far from the standards that can be reached with ceramic materials; this is due to the nature of the material itself and its higher abrasiveness (in the long term). The same can be said with regard to inner effects of absorbency and dispersion of light to simulate opales- cence of the enamel, which are far from those that can be achieved with glass-ceramic.
Several clinical studies and their follow-up results after 3 years have demonstrated that composite veneers show six times greater wear and abrasion than ceramic veneers. This is an important issue to consider, especially for clini- cians treating young adult patients with high esthetic ex- pectations.
Another point to consider is the material’s resistance to fracture, especially for patients who exhibit a high stress profile (eg, bruxism). From several studies we deduce that the fracture resistance of composites is under 2.0 MPa/ mm2, three times less than that of reinforced ceramic ma- terials.
An in-depth study by Ferraris and Conti11 highlights a very strict and meticulous protocol regarding the finishing and polishing of composite materials for reconstructions to prevent the formation of biofilm, which is responsible for the growth of bacterial colonies in the oral cavity.
Manufacturers of composite materials will likely make significant positive changes in coming years. When using composite resins for esthetic cases, we should keep in mind that some adjustments can be made in the future to compensate for deterioration and color changes due to plaque.
Ceramic Materials
The continuous advances in ceramic materials today have widened the options, providing the possibility to achieve a highly esthetic result in challenging cases as well as spe- cific multidisciplinary treatments (Fig 1). The literature is replete with studies that highly recommend ceramic mate- rials for achieving esthetic results in anterior teeth.
Other considerations for using ceramic materials are their optimum compatibility within the oral cavity, placing them in the category of biologically stable,20 and their high percentage of success over time, which has been shown to be approximately 93% at 10 years and from 91% to 94% at 12 years.21,22
Ceramic materials made from feldspar or glass-ceramic reinforced with leucite crystals or fluorapatite can be syn- thesized on refractory models (stumps) or platinum sheets with the Geller Dental Arch (the Geller model), taking ad- vantage of the translucence of the material.23 The best re- sult is achieved when, along with their individual abilities, clinician and technician work together toward the common goal.
The special nature of the material promotes highly es- thetic results, with thin ceramic layers up to 0.5 mm with or without enamel preparation. Unfortunately, its weakness is fracture resistance on applied force; with an elastic modu- lus between 50 and 120 MPa, ceramics are classified as a fragile material.25 The brittleness of the ceramic material has to be taken into consideration before the luting phase of the restorations. After luting, the brittleness is no longer relevant.
The even distribution of crystals (leucite, fluorapatite, etc) within the glass core changes the mechanical proper- ties of ceramics, making them more resistant to fracture. As the size of the crystal decreases, the material becomes more resistant.26 Ceramics reinforced with lithium disili- cate, with an average distribution of 70% lithium disilicate crystals in the glass material, are even more resistant to fracture owing to higher flexural resistance values.
Glass-ceramic cores can be obtained with several de- grees of translucency and opacity, allowing control of the value of the veneers from the core itself. Any defects in shape or enamel discoloration can be corrected as well. The use of ceramic layers with a lithium disilicate core is fundamental to obtain a satisfactory result, especially in anterior teeth.
The computer-aided revolution (CAD/CAM) has set a standard in production processes, with many benefits such as fewer internal flaws in milled materials.28,29 It is possible to mill ceramic blocks with matte or translucent core mate- rial, applying ceramic layers until the desired color and shape are achieved (Fig 2).
CASE PRESENTATION
A male patient, 18 years of age, presented for a consulta- tion in June 2013 (with Dr Carlo Ghezzi). The radiographs and clinical examination showed a deep bite greater than 60 degrees. Clinically, the patient presented a deep bite that had caused premature abrasion and severe wear of the maxillary and mandibular anterior teeth (Figs 3a to 3c). Upon diagnosis, a combined orthodontic/prosthodontic treatment was deemed necessary to repair the esthetics and function of the compromised teeth.
Orthodontic Treatment
The orthodontic diagnosis showed a Class II basal maloc- clusion, retracted mandible, misalignment of the maxillary incisors, severe wear of the mandibular incisors, and asym- metric wear of the maxillary anterior teeth due to the deep bite (parafunction) over time. The patient’s face had a nor- mal appearance, with the slight retraction of the mandible resulting in a convex profile (Figs 4a and 4b).
The orthodontic treatment plan included anterior torque correction and correction of the Class II malocclusion and of the deep bite (Figs 5a and 5b).
In October 2013, the orthodontic therapy began with temporary reconstruction of the most damaged teeth in order to position the orthodontic brackets. The therapy in- cluded the use of passive self-bonding materials due to their high torque resistance, strategic positioning of self- ligating brackets, and the selection of proper torque value for anterior teeth brackets. The strategic positioning of the same brackets was fundamental for correction of the mal- occlusion.
During treatment, while following protocols, certain cor- rections were needed to guarantee the end result (Figs 6a and 6b). After the Cu-Ni-Ti arch sequencing, the dental class was defined with metal archwires and 4.5-oz Class II elastics. Then the shape of the dental arches was defined with purple titanium molybdenum–alloy archwires, leaving the necessary space for the prosthodontist to restore the anatomical function and integrity of the anterior teeth. The orthodontic treatment was completed in October 2016 (Figs 7a to 7c).
Prosthodontic Treatment
In November 2016, six mandibular and four maxillary ante- rior teeth were prepared (by Dr Alessandro Conti) using a microscope (Zeiss Opmi Pro Ergo) with a minimally invasive approach and with a single retraction cord (Fig 8). The pro- tocol, based on the teachings of Dr Domenico Massironi,30 includes limited removal of tissue, preferably only enamel, and immediate hybridization of exposed dentin if neces- sary. The preparation of each tooth was made with the mock-up in place and was crosschecked with the silicone index. By this way it was possible to maintain a precise thickness.
For immediate dentin sealing, a 4th-generation adhe- sive (Total Tech 3 layers, Ceys) was used. Etching was done with 37% phosphoric acid (on the dentin for 10 to 15 seconds). After rinsing the etched surface with copious water and compressed air for at least 45 to 60 seconds, a 0.2% solution of chlorhexidine digluconate was applied for 1 minute (this inhibits the metalloproteinase present in the dentinal tubules). The dentin was dried without dehydrat- ing. A generous layer of primer was applied and kept in place for at least 60 seconds. It was dried completely and a thin layer of bonding agent was applied and then poly- merized for 60 seconds. Glycerin gel was applied for the final polymerization.
The single retraction cord (Gingi Aid 00) was put in place to deflect and control exposure of tissue (Figs 9a and 9b). After the positioning of the finishing line, two impressions were made using polyether impression material (Permadyne, 3M ESPE) single-application compound mix (Figs 10a and 10b).
Laboratory Phases
The development of the case started with a wax-up by the lab, as requested by the dentist, and then proceeded with the mock-up on the patient for reconstruction of the teeth. The impressions were cast in white extra-hard plaster (GC Fujirock EP, GC Europe). Once the cast models had been obtained (Figs 11a to 11c), white cosmetic wax was applied with special care given to the details that will guide the veneers.
The mock-up was made with a transparent silicone index filled with a dual composite (Protemp, 3M ESPE), in order to assess the esthetics (Figs 12 to 15).
After assessment of the mock-up and approval by the patient, the teeth were prepared as described previously, and the polyether impressions (Permadyne, ESPE) were sent to the lab for fabrication of the veneers.
Two master models were created for each arch. The first were created using the Zeiser technique (Zeiser Sockel-platten, Zeiser Dentalgeräte GmbH), sectioned with remov- able stumps. They were defined on the finishing line, mounting and setting on a dental articulator with dynamic facebow. Finally, the milled glass-ceramic cores were checked and arranged under the microscope with great precision (Stemi 1000, Zeiss) (Fig 16). The second models were made with polyurethane resin (Exakto-Form, Bre- dent), uncut to preserve the morphology of the gingival line, for completing the veneers and to be able to docu- ment the process and photograph the finished mold.
As always, the correct choice of core material is impor- tant to achieve the desired esthetic result. For this case, LT A1 (Ivoclar Vivadent) was used to ensure good passage of light and increase the value of luminosity. The lithium disilicate guaranteed more flexural resistance in this orth- odontic-prosthodontic combined therapy with a change of vertical dimension as well as adjustment to canine and in- cisal guidance. The material ensured a good longevity of the restorations.
Some core tests between the other cores and the exist- ing teeth were made on the patient for precision and cor- rect light balance. This phase guided the team to evaluate the patient’s new correct vertical alignment and functional guidance.
Two composite functional guides were made in the maxillary canine lingual area to achieve the best lateral guidance movement in this new position. Specific on-point information was required to bring back the patient to the centric position of the new vertical dimension of occlusion (Figs 17a to 17e). It is known that the first 2 to 3 mm of lateral guidance movement are important to avoid interfer- ence in the posterior area and to obtain a correct dynamic of function.
The core building of the veneers was completely digital, with the milling of the block of lithium disilicate in LT A1 color. The milling parameters for the cores were set at 0.4 mm, with five continuous axes and water cooling. Crystal- lization of these cores occurred in the heating unit (oven) at 840˚C. The time and temperature settings were estab- lished by the manufacturers of the materials.
The desired outcome was light-colored and natural- looking teeth that matched the texture of the surrounding teeth and young age of the patient (Figs 18 and 19).
The layering technique included application of Power Dentin (Ivoclar Vivadent) on the core masses and A1 color with a 20% addition of Dentin 1C desaturated at 50% with Neutral in the incisal third area to increase the translu- cence and obtain a wider passage of light. During the building of the tooth, light-absorbing masses31 were added also in the incisal third to recreate the opalescence and the light effect that is normally present at the patient’s age. All of this was done without losing control of the shape of the veneers (Figs 20a to 20d).
In the second bake of the ceramic, a small amount of Matte Orange Dentin was added in the proximal area to stop light there. The final enamel filter with neutral mass refinishes the shape and tones down the opalescence of the absorption masses.
In the final step, diamond burs cooled by water were used to achieve the desired texture, making grooves of different sizes for better light refraction.23,32 In the final baking phase, a thin glaze coating was applied, and the structure was polished with felt pads and diamond paste (Figs 21 to 24).
Luting Phase
The luting phase is of most importance to ensure a good prognosis over time. The luting agent bonds and stabilizes the two surfaces. To make this bond last, the clinician must follow a rigid processing protocol and must choose the correct type of luting agent based on its mechanical prop- erties and those of the restorations.
There are many texts explaining in detail how the proce- dure must be carried out correctly to achieve a good luting result.34 For this case, a 4th-generation total-etch adhesive (Optibond FL, Kerr) was used with microhybrid composite as the luting agent, heated to 52°C. A rubber dam was used for isolation of each tooth during the luting phase. All restorations were luted individually.
With constant pressure on the restoration, the excess luting agent was removed. Once all excess was removed and the restoration position was verified as correct, it was polymerized for 90 seconds on each aspect (buccal, incisal, palatal). The final polymerization was done with glycerin gel and the edges were cleaned with a curved blade. The same procedure was then carried out on the next tooth (Figs 25 to 32).
CONCLUSION
Careful planning, preparation of teeth with a minimally in- vasive approach, use of a surgical microscope for preci- sion, and the correct choice of materials for both restoration and luting are crucial to assure a successful and long-term restorative outcome.
Ceramic veneers that are adhesively luted and limited to the enamel represent the gold standard in cases requiring minimal correction to the shape and color of teeth and a conservative solution for preserving enamel.
Lithium disilicate glass-ceramic veneers are highly rec- ommended in cases of combined orthodontic and prosth- odontic therapy. Due to its mechanical properties, lithium disilicate provides good longevity for restorations in which there has been a change of vertical dimension and func- tional guidance.
Also requisite to achieve success is the dentist’s trust in the ability of each member of the team, especially the den- tal technician. This will go a long way in promoting excel- lent results for the patient (Figs 33 to 39).
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