Diagnostic Wax-Ups And Mock-Ups In Orthodontics

Introduction: In the past, dentistry was about treating dental diseases and preventing pain. But nowadays, the philosophy of esthetic and cosmetic dentistry guided the dental field into more challenging and advanced process. Patients now are looking for cosmetics in different ways, one of them is an esthetic smile with and ideal proportions, shades, and forms. In order to satisfy the patients’ demands according to their needs, full understanding of the situation and detailed treatment plan are required. Several diagnostic aids are provided to facilitate the diagnosis, help in treatment planning, provide better visualization for the dentist, and ease the communication with the patient as well as with the dental lab technician. Diagnostic wax-ups and mock-ups in dentistry have an impact on the treatment outcome provided to the patients. They are very helpful procedures when esthetic is required in dental treatment planning. They help the dentist in assessing the overall situation of the given case, and accordingly, set a goal and plan for it. What exactly are those diagnostic aids, what are the benefits and advantages of them, and what are the types and techniques used for each one of them are the main focus in these papers.

What is Diagnostic Wax-Up?

According to Glossary of Prosthodontic Terms, it is a procedure in dentistry which helps in planning for the future final restoration by building it with wax on a diagnostic cast to determine the needed laboratory and clinical procedures in order to achieve the desired esthetic and function of the restoration. (1)

Reasons and Benefits of Diagnostic Wax-Up: There are several studies indicated the importance of diagnostic waxing up, as this dental procedure has its benefits in achieving the goal of prosthetic dentistry, including (2,3):

• Having 3D representation of the case.
• Having illustration of the the case and how to improve the smile of the patient.
• Increasing patients’ acceptance.
• Helping in determining the requirement of teeth preparation, which in return will reduce the preparation time.
• Helping in designing the smile of the patient.
• Allowing better evaluation of anterior guidance and function.
• Revealing if there is a necessary treatment to be done that was not visible during clinical examination.
• Helping in temporization by creating good quality temporary restorations using temporary stents that can be fabricated based on the wax-up.
• Allowing better communication between dentists, patients, and dental lab technicians. Indications of Diagnostic Wax-Up: Diagnostic wax-up is indicated in all esthetic cases, not only the advanced cases of cosmetic dentistry. As the diagnostic wax-up provides better visualization of the end results, the following procedures require waxing-up (2):
• Veneers.
• Anterior crowns.
• Posterior crowns.
• Anterior or posterior fixed partial dentures.
• Cases that require advance cosmetics.
• Implants.

Requirements for Diagnostic Wax-Up: It is very important to write down a detailed prescription to the lab technician with details of the desired wax-up design, including important concerns and points, to enhance the communication between the dentist and the lab technician and hence, achieve the best possible results (3). However, in order to achieve a good wax-up that will represent the future final restoration of the case, some records are essential to have to be able to go through the diagnostic process and successfully achieve the goal that benefits the dental health of the patient. These records are including (4,5):

• Accurate impressions for maxillary and mandibular arches showing the needed details, in addition to bite registration in centric relation (CR), maximum intercuspation (MI), and protrusive bites.

• Face bow records.
• Full mouth and panoramic radiographs. (Cephalometric radiograph are indicated in case of orthodontic wax-up)
• Periodontal charting.
• Status of tempromandibular joint (TMJ), and muscles of mastication.
• Diagnostic photographs of the case with different intraoral views, as well as extraoral views to show the contour of the lips in un-retracted smile.
• Photographs with stick bite in case of any problems in the midline. Moreover, some notes are important to be mentioned, like; length of anterior teeth, esthetic concerns, the material to be used in the case, and if there is problem in soft tissue or if the soft tissue will be re-contoured. (3)

Types of Diagnostic Wax-Up: There are four main types of diagnostic wax-ups, according to the type of treatment that the patient needs. These types are; basic diagnostic wax-up, full contour wax-up, orthodontic wax-up, and case presentation wax-up (4).

1. Basic diagnostic wax-up: This type of wax-up helps in planning the overall procedure to be done, as it is considered the best way to visualize the treatment process. It uses minimal waxing in case of replacing deficient areas, or to visualize the improvement of the treatment after crown lengthening procedure. Moreover, it uses small amount of wax if the case requires addition of the cusp tips, lingual contours, or incisal length in order to improve esthetic or function. The main advantages of this type is the low cost, and short time required to do it. (4)
2. Full contour wax-up: It is the best choice in case of complete mouth rehabilitation. It uses larger amount of wax for visualization and to replace the deficient areas. It is also used when dental implants are indicated, where the teeth are completely removed to allow the dental technician to build up teeth with desired esthetic and function. This type of wax-up allows better fabrication of provisionals that matches the patient’s need. (4)
3. Orthodontic wax-up: This type of wax-up is very helpful in determining the available treatment possibilities during orthodontic treatment. It helps the orthodontists to determine whether the given case require interproximal reduction or not. If so, the orthodontist can determine the amount of reduction by measuring it through the wax-up. Orthodontic wax-up can be more accurate if there is more information about the case along with it, for instance; radiographs, periodontal information, and patient’s age. (4)
4. Case presentation wax-up: This is the least diagnostic type in compare to the other wax-ups. However, it is mainly used to show patients the end result of the planned treatment, and hence, to gain their acceptance. The teeth here are prepared as they will be in the patient’s mouth, then the wax will be built-up on the prepared teeth to show the future form of the restoration. Pink baseplate wax can also be used to simulate the soft tissues around the teeth. As this type of wax-up requires high skilled dental technicians, it could be costly and time consuming. (4) Diagnostic Wax-Up Technique: Fabricating the diagnostic wax-up by the dental technician requires full understanding of the main principles to achieve proper function with pleasing esthetically outcome. This needs careful considerations from the dentist as well as the lab technician specially in cases with full mouth rehabilitation.

Listed bellow the steps taken by the dental lab technician when fabricating diagnostic wax-up (assuming if the case requires full mouth wax-up) (6):

1. First of all, the maxillary and mandibular casts should be mounted in the articulator, using facebow record to mount the maxillary cast, and centric relation record to mount the mandibular cast. Any important detail should be noted down by the dentist, for instance; discrepancies in the midline or occlusal plane, or any other functional problems that may affect the treatment.
2. Waxing the maxillary anteriors followed by the mandibular anteriors, and that is to re-establish: -Labial aspect and inclination. -Length of the incisal tooth or the position of the incisal edge. -Location and inclination of the midline. -Incisal plane.
3. Waxing-up the the lingual side of mandibular anterior teeth to creat the lingual morphology.
4. Waxing-up the palatal morphology of maxillary anteriors, in order to; establish the contact between upper and lower anteriors including the space required to maintain the strength of restorative material, establish the vertical dimension, and to establish the functional pathway when moving from centric occlusion to eccentric position.
5. Waxing-up the buccal cusps of maxillary posteriors only, to establish cusps length, buccal corridor, and the occlusal plane of the patient.
6. Waxing-up mandibular posteriors to establish the hight of the buccal cusps, the occlusal plane, occlusal morphology, and the anterio-posterior with medio-lateral curves (curve of Spee and curve of Wilson, respectively).
7. Completion of waxing-up the maxillary posteriors in order to establish the centric occlusion (CO) contact, occlusal morphology, and the length of the lingual cusps.
8. Refinement as the last step to ensure proper function and well established occlusion. *It is very important for the dentists to fully understand each step undertaken by the dental lab technician when diagnosing the patient and writing down the treatment plan, to gather all the information needed for this step (6)

What is Mock-Up?It is basically the clinical equivalent of the diagnostic wax-up that was done in the dental laboratory. It uses tooth colored restorative materials to demonstrate how the final result will look like. In this case, selecting a proper restorative material is a very important step, as the color of the material may have an effect on the shape of the restoration. (1)Reasons and Benefits of Mock-Ups: Mock-ups are very important and helpful tool that aids in diagnostic evaluation as well as esthetic evaluation. It allows the diagnostic assessment of the case on study models or directly on the natural teeth. Esthetic evaluation can also be done using mock-ups whether on unprepared, partial prepared, or full prepared teeth. It is considered a good tool to show patients the end result of the future treatment and gain their acceptance. (7,8,9)Types of Diagnostic Mock-Up: There are different types of diagnostic mock-ups than can be used in different situations, they are divided to; preliminary diagnostic mock-up, secondary diagnostic mock-up, removable mock-up provisional restoration, and fixed mock-up provisional restoration. (10)

Preliminary Diagnostic Mock-Up:

This is done before the fabrication of the diagnostic wax-up, to gain more clinical information about the given case. It uses direct composite resin intraorally to shape and contour the teeth, then evaluate the appearance of the patient and determine if additional changes are required or not. It is a helpful technique to evaluate patient’s phonetic by asking him/her to pronounced certain letters, along with evaluating the esthetic and making changes to achieve an acceptable smile. It is also used to convince the patient if a certain treatment plan is not suitable for his/her case. Black markers can be used to creat an illusion of short clinical tooth. This procedure is reversible as it doesn’t require any tooth preparation, acid etching, or bonding material. In case there was a composite e material on the tooth to be mocked-up, it is advisable to lubricate it to prevent adhesion to the composite material. Photographs could be a very helpful aid in obtaining more clinical information as well as helping in matching the contour of the teeth to the facial features. Moreover, impressions after direct composite mock-up can also be made as a record, then can be sent to the lab to be as a guide for the lab technician when fabricating diagnostic wax-up. (10)

Secondary Diagnostic Mock-Up:

It is also called “Overlay Prosthesis”. This is formed after the fabrication of diagnostic wax-up, using a silicone matrix. Then, this matrix is filled with auto-polymerization resin and placed on the teeth. After final polymerization, the matrix is removed and the resin will be mechanically retained on the teeth. This procedure is to evaluate the diagnostic wax-up clinically before any tooth preparation, and any adjustment can be made by direct composite and then transferred to the dental laboratory. (10)

Removable Mock-Up Provisional Restoration:

This type of mock-up is designed to allow patients to evaluate their appearance over the day among their family and friends. It can be used until final approval of the designed teeth is achieved. (10)

Fixed Mock-Up Provisional Restoration:

This type is also used for long term patient’s evaluation of esthetic and function. It is done by using silicone matrix of the diagnostic wax-up, after spot etching and bonding of the teeth. However, this technique cannot be used if the diagnostic wax-up needs tooth preparation. (10)CAD/CAM Mock-Ups Technique: Nowadays, the world of dentistry is moving towards the digital smile analysis and using advanced smile diagnostic aids to provide patients with the optimum results of the planned treatment. Using CAD/CAM (computer aided design, and computer aided manufacturing) technology in dentistry has a very huge effect on the treatments provided to the patients. It increases the efficiency in dental laboratory processing, quick fabrication, good control of restorations’ quality, and it has better materials that are more esthetically pleasing. In simple words, CAD/CAM software requires a copy of the patient’s teeth, and that is done by using intraoral camera directly inside the patient’s mouth, or by laboratory optical scanner to digitalize a cast model of the patient’s teeth. After taking the photos from intraoral camera of laboratory scanner, they will be transferred into a software package where dental restoration designs can be made on.

After that, the abutment teeth that will be reconstructed should be selected, then the shape and form of the tooth is chosen from a virtual library provided by the software. Teeth forms, shapes, and size can be manually arranged by the dental lab technician to fit the size and form of the dental arch. When the teeth are chosen that fits properly, they will be exported to a 3D printer which in turn will layer the restoration. However, this technique is used to fabricate diagnostic mock-ups, but does not fabricate provisional restorations. (11)

Conclusion

In conclusion, diagnostic wax-ups and mock-ups have the same concept, but are considered a laboratory procedure and a clinical procedure, respectively. The use of diagnostic wax-ups and mock-ups in dentistry is essential and very important specially in cases that require comprehensive treatment. It facilitates the treatment process, aids in better communication between the dentists, the lab technician, and the patient, provides better visualization that helps in diagnosis and treatment planning, helps in providing better provisionals, and aids in presenting the final result to the patients that increases their acceptance. Using the advanced technology in dentistry helps the dentist as well as the lab technician to provide better treatment outcomes with less time consuming and more comfort to the patients.