Dr. Anuradha Nemane, Dr. Saumil Sampat, Dr. Saloni Mistry, Dr. Komal Chawla, Dr. Ankita Walke
Professor and Head of Department,
Second year Post-graduate Student.
Department of Prosthodontics, Crown & Bridge.,
Y.M.T Dental College and Hospital, Kharghar.
Rehabilitation of anterior esthetic zone involves a multidisciplinary approach and has always posed a challenge to even a skilled clinician. An understanding of the science of color and its perception is crucial in success of the prosthesis. The importance of communication between clinician and technician can never be overemphasized in achieving predictable esthetic outcome.
Over the years different techniques have been formulated for communication of shade to the laboratory technician. The conventional method of shade communication with laboratory technician is through work authorization form. With the advent of technology, shade navigation tools have been developed.
The IPS emax Shade Navigation application (SNA) takes into consideration various factors such as stump shade, material thickness, choice of material and gives the recommendation regarding the translucency and shade to the technician. This clinical study is an attempt to evaluate the efficiency of a shade navigation tool to enhance the communication with the laboratory technician and ease in fabrication to create realism in fixed prosthodontics.
Keywords: Esthetics, Shade Navigation Application, Shade Communication.
Citations: Nemane A, Sampat S, Mistry S, Chawla K, Walke A. A Shade Navigation App - A Connecting Link. J Prosthodont Dent Mater 2021;2(1): 23-30.
The vivid colours of nature infuse a dash of brilliance into the vibrant landscapes of life. These colours not only bring joy and brightness into our lives, but are elemental to all forms of beauty. In prosthetic rehabilitation, it forms an important basis for achieving superior esthetics. It is a challenge for every clinician to determine and replicate the appearance of teeth as it requires humility, patience and perseverance to mimic nature to its closest sense and form. Colour is governed by visual and scientific components, it is communicated on a regular basis but often misunderstood.
Accurate colour reproduction with a myriad of restorative materials is a challenging task. So esthetic predictability of prosthesis and its camouflaging with adjacent dentition depends on amalgamation of the four important factors which are, shade selection, laboratory communication, choice of restorative materials and luting agent. Shade selection involves more than picking a tab from a shade guide and having the restoration of the same colour processed. Shade selection in dentistry can be performed by using both visual methods with a shade guide and instrumental methods such as using a spectrophotometer, a colorimeter, and, more recently, an intraoral digital scanner.
Esthetic rehabilitation can be achieved when all those participating in patient treatment work smoothly and efficiently as a team. This team includes the restorative dentist, auxiliary personnel, other specialists, and the dental technician. This teamwork is essential both at the treatment planning stage and during the clinical and laboratory phases. Communication between them is a crucial factor. Advancement in digitalization is not only limited to the fabrication materials and shade selection, but also in communication with the laboratory technician. Applications like The IPS emax Shade Navigation application (SNA App) by Ivoclar are available on all electronic devices and gadgets, which can enhance the communication with the laboratory technician.
The present study is a comparative evaluation of shade reproduction of two full veneered crowns, fabricated using both an empirical and digital way of communication.
A 26-year-old male patient reported to the department of prosthodontics with a chief complaint of discoloured and fractured maxillary anterior teeth. (Fig.1) Clinical and radiographic examination revealed that the left maxillary central incisor (21) and lateral incisor (22) were endodontically treated. Radiographic evaluation revealed no sign of periapical lesion and bone loss with respect to 21 and 22. Substantial amount of tooth structure loss was seen with endodontically treated 22.
After through clinical case evaluation and discussion with the inter-disciplinary team, a definite treatment plan was arrived at. All necessary patient consents were obtained before proceeding further. The definite treatment plan included a diagnostic wax-up followed by restorative procedures with a full veneer crown with 21 using monolithic lithium disilicate. Crown lengthening procedure was planned for 22 to obtain optimum ferrule. Post and core restorative build-up were planned to secure core material retention and to improve prognosis. Full veneered crown on 22 with layered lithium disilicate was planned.
Crown lengthening and post and core restoration
Crown lengthening was done with 22 with osseous recontouring. Post and core restoration was done for 22 with a fiber post (Hi- Rem fiber post, Overfibers, Italy) and dual cure core build- up material (LuxaCore Z Dual, Dental Milestones Gauranteed, Hamburg, Germany). (Fig.2) Patient was recalled for suture removal and tooth preparation after 7 days.
Tooth preparation for 21 and 22 was done for lithium disilicate crowns. 1.2mm to 1.5 mm of labial, palatal, axial and incisal reduction was done with 21 using a tapered round ended fissure diamond bur (model 5850.314.016 Brasseler, Germany). 1.5 mm of labial, palatal and axial & 2mm of incisal reduction was done with 22 using a tapered round ended fissure diamond bur (model 5850.314.016 Brasseler, Germany). (Fig. 3) Both teeth were prepared to receive a deep chamfer finish line. Immediate provisionalization was done with a direct method (Protemp 4, 3M, Maplewood, Minnesota, United States).
Final Impression and shade selection
Gingival displacement with cord (size 000, Dental Medi -Pak Retraction cords, Medicept) was done with 21 and 22 to assure isolation. Final impression was made with two stage impression technique with a hydrophilic addition silicon impression material (Dentsply Aquasil, Dentsply Sirona, Pennsylvania, United States)
Shade selection was done under natural sunlight. (Fig.4,5) Stump shade was selected with stump shade guide (Natural Die Material, Ivoclar Vivadent, Schaan, Liechtenstein). Shade of adjacent teeth were selected with VITA shade guide (VITA classical A1- D4, VITA Zahnfabrik, Bad Sackigen, Germany).
For full veneer crown with 21- conventional approach was followed with the shade distribution chart (A2 shade) for monolithic lithium disilicate material with additional mentions about external staining. (Fig.6)
Fig. 6 – Shade Distribution Chart
For full veneer crown with 22- SNA Application was used (IPS e max Shade Navigation App, Ivoclar Vivadent, Schaan, Liechtenstein)
Steps involved in shade selection using the SNA tools= were as follows:
Prosthesis were fabricated with pressable lithium disilicate blocks (IPS e max press, Ivoclar Vivadent, Schaan, Liechtenstein)
- For full veener crown with 21- ceramic block was chosen by technician with his knowledge.
- For full veener crown with 22- ceramic block was chosen with help of shade navigation application and layering was done by a cutback method with technician’s judgement as per esthetic needs.
Final prosthesis placement
Final prosthesis were luted with dual cure cement as per manufacturer instructions.
Esthetic analysis using visual analog scale
Esthetic evaluation was done with 5 different prosthodontist who were unaware about treatment planning and who do not have any color discrimination disorders. They were asked to score the teeth on the scale of 1 to 10, where score 1 represented no match and 10 represented an absolute match. On the scale, score <7 was rejected and ≥7 was accepted.4 Mean was obtained for each prosthesis. Results obtained were-
Mean score obtained by expert’s opinion for monolithic lithium disilicate crown for 21 fabricated with conventional technique of communication with shade distribution chart was 7.2 (SD-0.4472) Mean score obtained by expertise opinion for layered lithium disilicate crown for 22 fabricated with novel technique of communication with SNA App was 7.8 (SD-1.3038).
The form, function, and esthetics of a restoration are of prime importance in its success. Bearing in mind that human teeth are not homogenous in colour or translucency, it is unrealistic to believe that natural tooth colour matching would not induce some errors in measurement and communication with the laboratory technician. Shade selection can be performed by using both visual methods with a shade guide and instrumental methods such as using a spectrophotometer, a colorimeter, and, more recently, an intraoral digital scanner. With the recent increased interest in esthetic dentistry, there has been increasing demand for these instruments for shade selection. Over a period of time, various shade selection methods were invented and compared in literature.
If Alshiddi et al5 in 2015 conducted a study on a comparison of conventional visual and spectrophotometric shade taking by trained and untrained dental students. He concluded that matching the shade of natural teeth using a spectrophotometric device is more accurate than a conventional method using a shade guide. However, knowledge and training on colour science and shade selection significantly affected the results. Walleska Feijó Liberato et al6 in 2018 conducted a study on a comparison between visual, intraoral scanner and spectrophotometer shade matching. He concluded that, Instrumental methods for color shade matching were more reliable than the visual methods tested. Riccardo Marzola2 et al in 2000 in his article, described several relatively straight forward techniques that can assist in patient- dentist communication and allow the patient to visualize a reasonable facsimile of the definitive result prior to initiation of irreversible therapy.
Indeed, there are no methods of communication with lab technician mentioned in the literature. The empirical way of communication is shade distribution chart. With the advent of technology and digitalization, a new shade navigation application has been introduced recently that is the IPS emax Shade Navigation application. In this shade navigation application, various parameters are noted and result is auto generated by the application. The result will provide a block of variation in translucency from which prosthesis is fabricated. It gives the technician a baseline idea to begin. These suggested blocks can be used either for monolithic restoration or a coping of core ceramic material. Whereas, in conventional technique it entirely depends on the technician experience and expertise to achieve the desired esthetic outcome.
SNA by Ivoclar demands certain criterion, that is availability of both Natural Die Material shade guide for matching tooth stump shade and Vita classical shade guide for adjacent teeth. However, in cases of inaccessibility of the translucency block suggested by application, clinicians have to rely on technician’s knowledge. In cases with higher demand of shade gradation, layered restorations are indicated. In these case scenarios, this application is limited for the selection of coping or core ceramic material. For the precise details and gradation of shade, clinician has to rely on technician’s proficiency.
Conventional methods thus depend upon the technician’s expertise whereas the novel technique using the shade navigation app, being very brand specific can be only used for monochromatic case scenarios. Judicious shade selection in different clinical scenario should be a combination of both conventional and novel technique. To achieve desired esthetic outcome appropriate knowledge of science, esthetic principles and the technology is crucial. It also depends on various factors such as contralateral tooth and stump shade, lightning conditions, choice of materials, luting agents. Along with these factors the role of communication cannot be overlooked. Technology should be used as an adjuvant to overcome subjectivity and errors. The key to achieve esthetic realism lies in the symbiotic relation between the novel and conventional methods.
Communication and teamwork are key factors for achieving desired esthetic outcome. Adequate knowledge of science, esthetic principles and the technology is equally crucial. Blend of biology with technology to achieve a biomimetic prosthesis should be in such a way that even a prosthodontist eye cannot discern the difference
Conventional technique of communication of a shade selection and choice of a proper shade of ceramic block or ingot, depends upon the technician’s expertise. However, novel techniques using the IPS emax Shade Navigation Application (SNA App) gives a baseline suggestion of this choice which ideally can be used for monochromatic, monolithic or a coping for layered restoration. As the application is material specific, it demands the use of specific shade guides and particular ceramic blocks or ingots which limits the use of this application.
Nevertheless the SNA app serves as an indispensable tool, rather a road map which serves as a guide for the user, in this case the dentist, to help the laboratory technician to arrive at a decision for fabrication of the final prosthesis substantiated with sound knowledge of material and colour science.
Conflict of interest : No conflict of interest
1. Shikawa-Nagai S, Sato RR, Shiraishi A, Ishibashi K. Using a computer color-matching system in color reproduction of porcelain restorations. Part 3: A newly developed spectrophotometer designed for clinical application. Int J Prosthodont. 1994;7(1):50-5.
2. Marzola R et al, The Science of Communicating the Art of Esthetic Dentistry. Part I: Patient-Dentist-Patient Communication, J Esthet Dent 2000;12:131-138.
3. Hugo B, Witzel T, Klaiber B. Comparison of in vivo visual and computer-aided tooth shade determination. Clin Oral Investig 2005;9:244-50.
4. Kalantari MH, Ghoraishian SA, Mohaghegh M. Evaluation of accuracy of shade selection using two spectrophotometer systems: Vita Easyshade and Degudent Shadepilot. Eur J Dent 2017;11:196-200.
5. IF Alshiddi, LC Richards, A comparison of conventional visual and spectrophotometric shade taking by trained and untrained dental students, Aust Dent J. 2015; 60: 176–181.
6. Liberato WF, Barreto IC, Costa PP, de Almeida CC, Pimentel W, Tiossi R, A comparison between visual, intraoral scanner, and spectrophotometer shade matching: A clinical study. J Prosthet Dent. 2019 121(2):271-275.