Masking a Metal Cast Post and Core Using High Opacity e.max Ceramic Coping: A Case Report.

RATIONALE: Advancements in dental biomaterials have led to the introduction and application of ceramic-based restorations in dental practice. Currently, ceramic restorations are used in crowns and fixed partial dentures. The optical properties of ceramic restorations are comparable to natural teeth in terms of light scattering and transmission. However, the translucency of ceramic restorations could be a limitation if cemented over metal posts or severely discolored dentin. Therefore, accomplishing the maximum esthetic outcome mandates adequate management of severely discolored foundation. PATIENT CONCERNS: The patient wanted to improve the esthetic of his anterior teeth. DIAGNOSIS: This case report describes a clinical case in which the patient had defective restoration in his upper anterior teeth and base-metal cast post and core in his left lateral incisor (tooth #22).
INTERVENTIONS: Metal-free full crowns were used in the anterior zone of the maxilla with the help of e.max HO (high opacity) coping to mask the dark core buildup of the base-metal post and core on tooth #22. OUTCOMES: The color of the substrate was masked completely. The esthetic of the anterior teeth was improved and the patient was highly satisfied with the outcome. LESSONS: e.max HO coping offers clinically acceptable masking ability. Copyright:

INTRODUCTION

In the recent years, esthetic restorative dentistry has become the center of attraction for both dentists and patients. The demand for nonmetallic, biocompatible, and highly esthetic restorations has increased notably.[1] For this reason, the ultimate objective of esthetic restorative dentistry is to restore missing or mutilated teeth structures with highly compatible, esthetic, and functional restorations.[1] Advancements in dental biomaterials have led to the introduction and application of ceramic-based restorations in dental practice.[2] Smile makeover using indirect ceramic restorations is widely accepted because of its biocompatibility, high wear resistance, tooth-matching optical properties, tooth-simulated surface texture, and high translucency with excellent esthetic and mechanical properties.[3]

Dentists frequently encounter mutilated dentations that require a post and core.[4] Some cases require custom-made posts and cores particularly when gross tooth structure is lost as well as in teeth with wide canals or when a change in angulation is required for enhancing the esthetics by repositioning the restoration in the arch.[5] Although metal-ceramic restorations can be used in these clinical cases, the metal substructure of these restorations prevents light transmission and achieving natural translucency with metal-ceramic restorations is difficult.[6] Consequently, it is not recommended to use metal-ceramic restorations on anterior teeth.

A metal post and core is routinely used in dental practice. The translucency of ceramic restorations will affect the perceived color when these restorations are cemented over metallic core.[7] Therefore, accomplishing the maximum esthetic outcome mandates adequate management of severely discolored foundations. This management could range from simple bleaching of discolored dentin to prosthetic alterations of the tooth and the indirect ceramic restorations.[8]

There is considerable interest in glass-ceramic lithium disilicate-reinforced structures as IPS e.max restorations. This type is widely used because of its excellent esthetics and biocompatibility.[9] It enhances biometric qualities such as enamel structure, longevity, mechanical strength, and chemical stability.[9] It is available in a five degrees of both translucency and opacity. There are three levels of e.max translucency blocks including high, medium, and low translucency (HT, MT, and LT).[10] By the same token, there are two levels of e.max opacity blocks known as medium opacity (MO) and high opacity (HO).[10] The highest level of shade masking is associated with the HO ingot, which is available in three shades (HO 0–HO 2).[10] These can be used as a framework on severely discolored teeth.[10] Therefore, the objective of this study was to present a clinical case in which metal-free full crowns were used to reestablish the esthetic of the upper anterior teeth with the help of e.max HO coping on a base-metal cast post and core that offered clinically excellent masking ability.

CASE HISTORY

A 34-year-old male patient presented to the restorative department with a chief complaint of unpleasant esthetics and multiple defective composite restorations in the upper anterior teeth [Figure 1A and B]. The past dental history included recent trauma to the upper anterior teeth, defective anterior and posterior restorations, chipped central incisor, multiple root canal treatment, and base-metal cast post and core in his lateral incisor (tooth #22) covered by a temporary crown. The findings of the extra-oral examination were all within normal limits. Periodontal examination revealed good oral hygiene with no gingival inflammation or bleeding during probing. The patient’s medical, family, social, drug, and other related history were insignificant.

Figure 1

(A) anterior view with unpleasant esthetics in the anterior zone of the maxilla and (B) intra oral view of maxillary dentition

Preliminary impressions were made with an irreversible hydrocolloid (Jeltrate Plus, Dentsply, York, PA) from which diagnostic casts were obtained. The upper cast was used for a diagnostic wax-up [Figure 2]. Both casts were presented to the patient. The patient wanted a time efficient and most conservative treatment approach, and therefore a treatment plan of prosthetic rehabilitation of upper anterior teeth was discussed. The treatment consisted of crown preparation of the upper six anterior teeth followed with a fiber post and core fabrication when indicated. Finally, e.max (lithium disilicate) ceramic crowns for all upper anterior teeth (canine to canine). After the patient accepted the discussed treatment, a written informed consent was taken from him, and ethical approval for this study was obtained from the institute. After that, preparation and temporization of the upper six anterior teeth were carried out. The structure of the remaining teeth was assessed. Fiber posts and cores were done for teeth #13, 11, 21, and 23. All of these teeth received size 1 tapered fiber post (RelyX Fiber Post, 3M ESPE, St. Paul, MN) and cemented with dual-cure self-adhesive resin cement (RelyX-unicem, 3M ESPE, St. Paul, MN). Tooth #22 previously had base-metal cast post and core over adequate root canal treatment. A putty index was prepared over the wax-up. The index was used to prepare the temporary crowns. Full crown preparation was carried out for all anterior teeth [Figure 3]. Double retraction cords size 00 (Ultrapac, Ultradent, South Jordan, UT) impregnated in 25% aluminum chloride hemostatic agent were used to achieve blood-free atraumatic gingival retraction (Viscostat Clear Ultradent, South Jordan, UT). The stump shade for the natural teeth was determined to be ND2 [Figure 4]. The final shade selection for the e.max crowns was conducted manually using Ivoclar Vivadent shade guide (Ivoclar Vivadent, Schaan, Liechtenstein) and selected to be A2 cervically and A1 incisally [Figure 5]. After that, final impression was taken for the prepared upper teeth using multiple mix impression technique with light and regular viscosity elastomeric impression materials (Hydrorise Light body and regular body, Zhermach SpA, Badia Polesine, Italy). The provisional restorations were formed using bis-acrylic-based composite resin material (shade A2; Protemp 4, 3M #SPE, St. Paul, MN) and cemented temporarily using eugenol-free temporary cement (Temp-Bond NE, Kerr S.R.I, Scafati, Italy) [Figure 6].

Figure 2

Diagnostic wax-up—frontal view

Figure 3

Anterior view—teeth preparation

Figure 4

Anterior view—stump shade selection

Figure 5

Anterior view—shade selection

Figure 6

Anterior view with provisional crowns

The presence of the base-metal core on tooth #22 was a challenging clinical situation to reestablish harmonious and esthetically pleasing e.max crowns on the upper six anterior teeth. Therefore, an HO block of e.max coping was prescribed with a thickness of 1.2 mm to mask the metallic shade of the underlying metal core. This HO coping was fabricated using the traditional “wax and press” technique. All of the upper anterior glass-ceramic crowns were then pressed using MT blocks (IPS e.max Lithium Disilcate; Ivoclar Vivadent, Schaan, Liechtenstein) with cutback to facilitate porcelain layering technique to maximize the esthetic outcome (IPS e.max Ceram; Ivoclar Vivadent, Schaan, Liechtenstein) [Figure 7A–C].

Figure 7

(A) e.max ceramic crowns and HO e.max coping. (B) and (C) all upper anterior e.max crowns

Try-in of the HO coping was done on tooth #22 to verify the coping seating on the prepped finish-line and complete obscuring of the metal shade of the metal core. The e.max crown of tooth #22 was fitted over the HO coping to verify the complete seating of the e.max crown on the coping substructure. Then, all e.max crowns were fitted to verify proper seating and esthetic outcome. After patient approval of the esthetic outcome, all the surfaces of the HO coping and fitting surfaces of the e.max crowns were etched for 90 s using hydrofluoric acid (Porcelain Etch, Ultradent, South Jordan, UT) then salinated for 60 s (Monobond Plus, Ivoclar Vivadent, Schaan, Liechtenstein). The HO coping was cemented on the tooth #22 using resin cement (Variolink Esthetic DC, Ivoclar Vivadent, Schaan, Liechtenstein). Light curing was done based on the manufacturer’s instructions, and excess cement was removed [Figure 8]. As per the manufacturer’s instructions, all-ceramic crowns were cemented with resin cement, light cured, and excess cement was removed [Figure 9]. Upon examination at two-week-follow-up, there was no evidence of metallic hue effect on the final e-max crown on tooth # 22. This confirmed that full masking had been achieved, and the patient was highly satisfied with the results [Figure 10].

Figure 8

Anterior view with cemented coping on tooth #22

Figure 9

Anterior view with cemented e.max crowns

Figure 10

Anterior view, two-week post-operative photo

DISCUSSION

The excellent properties of all-ceramic restorations have led dentists to shift from metal-ceramic to metal-free restorations. However, such restorations are difficult in cases with an underlying metallic core because of the unacceptable grayish hue seen under these restorations. Previous studies have found that the underlying tooth structure has a primary influence on the appearance of the ceramic restoration.[111213] Accordingly, a clinician should consider this issue when treating such cases. The final color of a ceramic restoration depends on a combination of different variables such as ceramic opacity degree, ceramic thickness, color of the underlying substrate, and the color of the cement.[14] The color of the substrate has a primary influence on the final appearance of the ceramic restoration.[11] On the contrary, the color of the cement has the least effect on the final shade of the definitive ceramic restoration.[7]

The dental literature suggests different approaches to mask the color of the substrate including but not limited to increased thickness of the ceramic material,[12] using opaque luting cement,[14] using HO zirconia material, or using ceramic systems containing a ceramic substructure with shade-masking properties.[13] Clinical situations of discolored teeth or dark-colored abutments can be masked with a ceramic layer that will enhance the outcome of the final restoration and give an excellent esthetic result.[15] This can be achieved with either zirconia or e.max copings.

A recent study compared the masking ability between e.max HO and Lavaä Zirconia white coping in different thicknesses under a light dentin colored stump and a dark colored wax stump and found that opacity of e.max HO ingots is superior to that of Lava Zirconia in masking dark stump shade.[16] The study suggested that 0.5–0.6 mm thickness of e.max HO coping is sufficient to effectively mask the underlying structure.[16] This observation was confirmed by Zhou et al.,[17] study, which evaluated the masking ability of IPS e.max all-ceramics system of HO series and found that ceramic disks of HO 1 e.max with a thickness of 0.4 mm were negatively affected by the dark background. Thus, this thickness could not produce a pleasing restoration outcome. The study results suggested a thickness of 0.6–1 mm to mask the dark color of metal substrate.

The stump shade is one of the most essential pieces of information that a clinician needs to pass on to the ceramist when working on any metal-free restoration. The ceramist will use this information to make a model die that is the same shade as the preparation and will confirm that there is no shade change or show-through the ceramic from the underlying tooth structure. These can have a significant impact on the final outcome of the restoration.[16]

Esthetic rehabilitation of upper anterior teeth is always considered to be a major challenge.[1] The difficulty of each esthetic case is proportionally increased because multiple dental disciplines are involved in the management of a deteriorated smile.[1] The treatment of the upper anterior teeth could be complicated by many factors. These factors include, but are not limited to, teeth shape and size discrepancy, old faulty restorations, teeth malalignment, and unaesthetic gingival contour.[1] Therefore, a comprehensive and detailed treatment plan is crucial to identifying both esthetic and functional treatment needs. The use of a diagnostic wax-up, detailed facial and dental esthetic analyses, and proficient communication with the lab technician are required to achieve the most predictable esthetic outcomes.[18]

CONCLUSION

The final esthetic outcome of all-ceramic restorations is influenced by the underlying shade of the abutment. Hence, managing cases with a metallic core using all-ceramic restorations represents a major challenge. This case report shows the clinical procedures of using HO e.max coping to mask the metallic core material to improve the final esthetic outcome and to achieve a pleasant smile for the patient.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.