Phasing Complex Treatment for Adolescent Patients with Orthodontic Needs

Patients presenting to to the dental office with widespread enamel defects or congenital enamel hypoplasia can present unique challenges for an operator charged with restoring the compromised teeth to proper form, function, and esthetics.  These challenges are exacerbated when the patient is young or adolescent, as transitions through the mixed dentition phase and long-term appositional downward and forward growth of the maxillo-mandibular complex must often be considered.  Perhaps one of the most demanding cases to address is a patient who presents with multiple criteria listed above and is in need of orthodontic treatment (figure 1a, 1b, 1c).  Addressing compromised hard tissue is paramount in treating these cases, as establishing oral health will provide the basis for numerous future treatment modalities.  Moreover, poor enamel quality can compromise the ability of the orthodontic provider to bond brackets when clear aligners are insufficient to address orthognathic discrepancies.   

Figure 1a; A panoramic radiograph of the patient

Figure 1a; A panoramic radiograph of the patient

Figure 1b; A cephalometric radiograph of the patient

Figure 1b; A cephalometric radiograph of the patient

Figure 1c; A retracted (1:3 magnification) view of the patient’s dentition pre-treatment

Figure 1c; A retracted (1:3 magnification) view of the patient’s dentition pre-treatment

The following patient (a 17 year old male) presented with chief complaints related to his bite and the appearance of his teeth.  The patient and his parent were both aware of the poor enamel quality, since older siblings have experienced the same condition.  Upon initial exam, the following dental problem list was developed:

® Poor enamel quality relating to poor oral health and high caries risk

® Poor enamel quality for bonding orthodontic brackets

® Altered passive eruption

® Abnormal tooth morphology

® Dental caries, attrition, and fracture of tooth structure

® Retained primary teeth O and P with no succedaneous teeth

® Conjoined supernumerary tooth associated with the upper left second bicuspid

® Skeletal inequity affecting facial profile and causing occlusal discrepancy

® Fair oral hygiene and gingival inflammation

® Impacted third molars (#1,16,17) and upper right second molar (#2)

® Dental esthetics

(figure 2a, 2b, 2c)

Figure 2a; A retracted right lateral view (1:3 magnification).

Figure 2a; A retracted right lateral view (1:3 magnification).

Figure 2b; A view of the maxillary anterior teeth (1:1 magnification).

Figure 2b; A view of the maxillary anterior teeth (1:1 magnification).

Figure 2c; An occlusal view (1:3 magnification). Note the conjoined supernumerary tooth on the mesial aspect of the upper left second bicuspid.

Figure 2c; An occlusal view (1:3 magnification). Note the conjoined supernumerary tooth on the mesial aspect of the upper left second bicuspid.

The patient was referred to the orthodontist for further evaluation, and the following orthodontic findings were reported:

® Class II Malocclusion

® Poor spacing and tooth size discrepancy

® Severe overjet with deep, impinging overbite

® No TMJ problems found

® Centric Relation appears to be equal to Centric Occlusion

An orthodontic treatment plan was developed.  Comprehensive orthodontics was recommended, with a focus on utilizing elastics and Forsus appliances to correct the Class II occlusion.  Surgical mandibular advancement would be considered if non-surgical modalities proved to be insufficient in correcting the Class II occlusion.  Initially, bite blocks were treatment planned to open the deep bite, but it was decided that an increase in Vertical Dimension of Occlusion (VDO) could be accomplished within the context of the restorative plan.  Impressions were taken and casts were made and digitized (figure 3a). Case planning was done in combination with the restorative doctor, the orthodontist, and the digital dental laboratory technician by utilizing 3Shape Software and Computer Aided Design (CAD) (figure 3b).

 Figure 3a; Digitized pre-operative models.

Figure 3b; CAD / CAM design of the case.

The main goals of the restorative plan were numerous and varied.  Establishing oral health by removing compromised hard tissue was foundational to the success of the treatment plan.  Restoring the teeth to proper form, function, and esthetics after the surgical removal of affected and infected hard tissue was considered essential to successful treatment.  The restorative plan included not only esthetic correction within the limitations of the existing orthognathic condition, but also an increase in VDO to accommodate orthodontic movement of the anterior segments to correct the deep bite.  The teeth needed to be restored individually to give the orthodontic provider control over root and tooth movement.  Additionally, the teeth would need to be restored with a material suitable for accommodating adhesive bonding of orthodontic brackets.  A final consideration in the initial restorative therapy was to provide the patient with semi-permanent restorations, as the changes to occur through orthodontic treatment and continued appositional growth would undoubtedly alter the location and presentation of the teeth within the maxillo-facial complex.  Composite was selected as the most suitable restorative material to achieve the initial treatment goals.  The patient was made aware that ideally, the composite crowns would be replaced sequentially with definitive dental ceramics after a proper orthodontic end point was achieved and growth was complete. Additionally, gingival plastic surgery was indicated to address the altered passive eruption, as 5-7 mm of soft tissue was present between the alveolar crest and gingival margin of multiple teeth. For initial therapy, gingivectomies with internal beveling and trans-sulcular crown lengthening would be performed to increase tooth length and maintain biological width (figure 4). Primary teeth O and P were incorporated into the restorative plan. It was decided these teeth would be retained as long as possible before extraction and definitive replacement with implants or a fixed partial denture. Initially, endodontics and removal of the supernumerary tooth conjoined to the mesial of tooth #13 was considered.  After CBCT evaluation of pulp horn location, it was determined that the conjoined teeth would be treated as a single tooth, and preparation design would include the supernumerary tooth, despite a small esthetic compromise due to excessive mesial-distal width (figure 5a-b).

Figure 4; Representation of the dentogingival complex (biologic width).

Figure 4; Representation of the dentogingival complex (biologic width).

Figure 5a; CBCT evaluation of tooth #13 and conjoined supernumerary tooth, along with the proposed restoration design.

Figure 5b; The modified preparation of conjoined supernumerary tooth

Figure 5b; The modified preparation of conjoined supernumerary tooth

It was decided that the restorative plan could be used to increase the VDO to facilitate orthodontic movement of the anterior segments by creating space.  Although it is arguable that this should be the primary reason for an increase in VDO, it is important to consider that bite blocks would have been implemented to create a vertical increase anyway. Additionally, it was apparent that tooth structure had been lost due to caries, fracture, or attrition in the posterior, suggesting a collapse in verticality had occured, and that replacing the lost vertical dimension should be part of restoring the posterior teeth. Caution should be implemented in increasing the VDO of patients with Class II occlusion and deep bite.  As the vertical dimension (overbite) is increased, so too is horizontal dimension (overjet).  This can cause problems related to speech and mastication (especially incising food) if the increase is too great.  For this patient, who initially presented with a severe overbite and is committed to undergoing orthodontic treatment to better relate the anterior segments, the potential for temporary negative effects was a tolerable risk to facilitate the final outcome.  As previously stated, the VDO was increased largely to give the orthodontist room to re-position anterior segments of upper and lower teeth, thereby providing the operator and lab technician with only a broad target range of how much vertical space to create. General guidelines related to increasing VDO were followed, and a 4 mm increase in VDO was agreed upon by the general dentist and orthodontist.

To address the collapsed dentition and skeletal deep bite, the maxillary central incisors and maxillary canines provided key information for planning the case. Commonly, the central incisors can help discern the amount of vertical increase needed.  As a guideline, a measurement taken from the Cemento Enamel Junction (CEJ) of the maxillary central incisor to the CEJ of the lower central incisor should be 16 - 18 mm in a Class I patient and 14-16 mm in a Class II patient. These measurements can provide guidelines (not justification) for the necessity and amount of vertical increase; if the CEJ - CEJ measurements are collapsed (less than the average values) an increase in VDO may be necessary (in a standard patient). The dimension of the patient’s central incisors was deficient, especially in length, and diastemas were present. The CEJ-CEJ measurement was only 11 mm (figure 6).  Increasing incisal length was done minimally and judiciously to create symmetry, as the position of the central incisors and incisal edge in the patient’s face was appropriate.  Tooth length gain could however be accomplished in an apical direction by performing gingivectomy with internal beveling.  When sounding bone, it was discovered that the alveolar crest was located 4 - 6 mm from the gingival margin in the anterior segment, confirming that the actual CEJ of the maxillary central incisors is positioned more apically than the gingival margin would suggest.  By relieving 3 mm of soft tissue and severing the connective tissue attachment, a 3 mm gain in tooth length could be achieved while still providing 3 mm for biologic width.  In areas where 3 mm of space to accomodate biologic width was not available, a chisel was used to remove small amounts of the crestal bone through the sulcus (figure 7a-e). A new measurement from CEJ-CEJ would then be 14mm, which is more normative for a Class II patient. Only the canines were treated with plastic surgery at the time of initial treatment. Although evaluation of the dento-gingival complex relating to the central and lateral incisors was essential for treatment planning, it was decided surgery would be done after re-evaluation when a stable orthodontic endpoint was reached and growth was complete.

Figure 7a-e; a) Periodontal probe reading of the sulcular depth is 3 mm. b) When sounding bone, the periodontal probe reading approaches 6 mm. c) Gingivectomy to relieve excess tissue and contour gingival shroud (note the amount of enamel apical to the initial gingival margin posititon). d) Internal bevel to sever the connective tissue attachment. e) a bone chisel with a laser etched 3 mm marking to ensure adequate space for biologc width between the crestal bone and the new gingival margin position.

As detailed by Dr. Carl Misch, the canine position is a key indicator for planning tooth position relative to the maxilo-facial complex.  Although some apical gain could be created by performing gingivectomy on the canines, it was clear that orthodontics would be required to continue apical movement to position the teeth (especially the canines) in the proper location.  Although 3 mm worth of gingivectomy could help with the canine tooth length, apical gain alone would not be adequate to position the teeth correctly in the maxillo-facial complex.  The acceptable range for canine exposure in relation to the maxillary lip line varies, but Misch found that the range of canine display in a lip at rest position varies far less than that of central incisors.  Our goal for the patient was to have 0-1 mm of the canines visible in a lip at rest position.  Gingivetomy with internal bevel and trans-sulcular bone removal was to be performed, but it was determined that the canine would still need to move apically 3 mm to be in the proper location in the face. Because the initial restorative phase would be interim in nature, the VDO change could be adjusted as necessary; either to accommodate orthodontic movement or to relieve possible TMD symptoms due to the patient being unable to accommodate the new VDO.

Figure 6; CEJ-CEJ measurement (11 mm) and maxillary right central incisor measurement (8 mm long x 8 mm wide).

Figure 6; CEJ-CEJ measurement (11 mm) and maxillary right central incisor measurement (8 mm long x 8 mm wide).

Overall, the case was designed as a full mouth rehabilitation.  The design included considerations related to tooth proportion, gingival zenith location, increased vertical dimension, esthetic correction, and stable occlusion.  The plan was representative of initial therapy with the intention of being revisited after completion of orthodontic treatment. 

Transfer of the plan to the patient’s dentition was completed using deliverables from the dental laboratory and composite resin.  In the Computer Aided Design / Computer Aided Manufacturing (CAD / CAM) software, the complete design of the corrected maxillary and mandibular arches was printed using a 3D printer.  Then, the initial design was altered so that only every-other tooth was corrected, while every-other tooth remained in its pre-operative state (figure 8).  A set of models representing a correction of every-other tooth for each arch was also printed.  Clear matirces were made on each set of models.  Clinically, the patient was anesthetized, and soft tissue corrections were made using a 15C Scalpel and bone chisel.  Next, every-other tooth was treated by removing unhealthy hard tissue before being prepared for the composite restoration.  Retraction cord was placed in the gingival sulcus of the prepared teeth. The unprepared teeth adjacent to the prepared teeth were protected with strips of sterilized polytetrafluoroethylene (PTFE) tape to prevent unintentional adhesive bonding.  A 37% phosphoric acid etch was used in a total etch technique, desensitizer (MicroPrime G, Danville) was applied to the prepared tooth structure and adhesive (Prime&Bond Elect Universal Dental Adhesive; Denstply Sirona) was applied for 20 seconds and light cured for 10 seconds.  The clear matrix was fit over the unprepared teeth and shade A2 flowable composite (Herculite Ultra-flow Nano-hybrid; Kerr) was injected through a porthole created in the matrix prior to placement (figure 9a-d).  The composite was cured through the matrix for 20 seconds on each surface; the excess material was trimmed and the restorations were contoured before the next set of teeth were prepared (figure 10a-b). This process was repeated for the remaining teeth.  The occlusion was adjusted as necessary and the final composition was then polished.  The patient was re-appointed for a 3-week re-evaluation to ensure the increase in vertical dimension was not problematic, and that stomatognathic functions such as eating, swallowing, and speaking were not compromised.

Figure 8; The “every-other” model in CAD / CAM software.

Figure 9a-d;

Figure 10a ;

Figure 10a;

Figure 10b;

Figure 10b;

Ultimately, each tooth was restored individually to enable individual orthodontic root and tooth movement while providing a bondable substrate for orthodontic brackets.  Although provisional, the restorations offered the patient immediate improvements in oral health, and in the form, function, and esthetics of his teeth.  Furthermore, because the restorations are not considered definitive, the prototype is dynamic and able to be altered during continued restorative and orthodontic treatment; unlike dental ceramics, composite can be easily removed from or added to. Furthermore, the living prototype will provide valuable information before the dentition is to be definitively restored.  Although cases like these require intensive planning pre-clinically and many chair hours clinically, the initial improvements are extremely rewarding.  Given proper treatment planning and coordination between the operator, orthodontist, and lab, cases like this can be extremely fun to execute!

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Dr. Ryan J. Yakowicz, DDS, FAGD

Dr. Yakowicz practices in the Greater Madison Area of South Central Wisconsin. Having completed over 775 hours of continuing education, his special interests include functionally cosmetic full mouth rehabilitation, TMD and oral-facial pain, and surgical implant placement and prosthetic restoration.

Dr. Yakowicz is currently the president of the Madison Dental Progress Forum Study Club and the Wisconsin Institute for Advanced Dental Education. He is a Fellow of the Academy of General Dentistry, and is a member of the American Academy of Cosmetic Dentistry, and the American Academy of Fixed Prosthodontics. Additionally, Dr. Yakowicz participates in research studies for the National Provider-Based Research Network and is an Ambassador to the National Health Service Corps.

References:

1)     Spear, F (2006) Approaches to Vertical Dimension.  Advanced Esthetics and Interdisciplinary Dentistry 2 (3): 2006: 2-12.

 

2)     Kois, J, Phillips, K (1998) Occlusal Vertical Dimesnion: Alteration Concerns.  Compendium 18 (12): 1998: 1169-1177.

 

3)     Rivera-Morales WCMohl ND.  Relationship of occlusal vertical dimension to the health of the masticatory system. J Prosthet Dent. 1991 Apr;65(4): 547-53.

 

4)     Terry, Douglas A., Willi Geller, and Douglas A. Terry. 2013. Esthetic & restorative dentistry: material selection & technique. Chicago: Quintessence Pub. Co.

 

5)     Misch, CE.  Guidelines for maxillary incisal edge position-a pilot study: the key is the canine.  J Prosthodont. 2008 Feb;17(2):130-134.

 

6)     Terry D, Powers J, Blatz M.  The Inverse Injection Layering Technique.  Journal of Cosmetic Dentistry. 2018 Spring; 34 (1): 48-62.

 

7)     Coachman, C.  Emotional Digital Dentistry.  Journal of Cosmetic Dentistry.  2019 Winter; 34 (4): 36-42.

8) Lyons, L, English, J. In Vitro Shear Testing of Orthodontic Bonding to Lithium Disilicate Ceramic. Journal of Cosmetic Dentistry. 2019 35 (1): 82-89.

 

Start to Finish Veneers: Part 2, Preparation and Provisionalization

It must be said that there are many methods for preparing teeth for cosmetic restorations such as labial veneers.  The comfortability and personal preference of the operator that best suits his or her skill set and background in cosmetic restorative dentistry is not to be overlooked.  What follows is simply one method to achieve pre-planned restorative goals of the operator and patient.

Figure 1; The prototype of the desired outcome transferred intra-orally.

Figure 1; The prototype of the desired outcome transferred intra-orally.

After the prototype is verified by the patient and the dentist, the preparation phase of treatment can commence.  The patient is anesthetized and an Optragate (Ivoclar Vivadent) is used for general isolation and retraction.  The prototype is not removed, but rather utilized as a facial and incisal reduction guide that is based on the final objective.  By leaving the prototype in place, tooth reduction can be performed relative to the restorative plan instead of being performed relative to the existing tooth surface.  Different portions of different teeth may require more or less reduction to create a near-uniform space that will accommodate the thickness of the selected restorative ceramic material without unnecessarily removing hard tissue.  The operator should perceive this process as an exercise in creating minimal space to achieve the restorative outcome, which is a very different perspective than removing a certain amount of tooth structure solely due to a preset preparation parameter.  For this case, lithium disilicate (IPS e.Max, Ivoclar Vivadent) was selected as the restorative material for its esthetic qualities, flexural strength, and ability to be bonded using an adhesive resin cement.  According to the manufacturer, veneer thickness should be between 0.3 mm and 0.7 mm depending on what portion of the tooth is being restored, what material is being used, and whether the restoration will be milled or pressed[1].  This is more or less consistent with instructive literature regarding tooth preparation for bonded ceramic veneers[2].  For this case, the goal was to create a space to accommodate ceramic restorations that would be 0.5 mm – 0.7 mm thick in the facial and interproximal areas, with slightly less space considered in the cervical-facial planes of the teeth and slightly more space considered in the middle-facial and incisal-facial planes of the teeth.  The necessary space for the incisal edge would be 1.5 mm to fulfill both the functional occlusal demands of the restorations and allow the ceramic technician space to create micro-esthetics and translucency at the incisal edge of the restorations.

Figure 2; Depth cuts through the in-place mock-up.

Figure 2; Depth cuts through the in-place mock-up.

Figure 3; 834 - 021 M diamond depth cutting bur (0.5 mm).

Figure 3; 834 - 021 M diamond depth cutting bur (0.5 mm).

To achieve this, depth cuts are made through the mock-up (figure 3) using a 0.5 mm depth controlled bur (834 – 021 M, figure 3).  Care is taken to advance the bur into the proximal areas, as adequate space for the indirect restoration is often not attained in this area.  By leaving the prototype in place and using a bur with controlled depth, areas requiring more tooth removal to achieve the final design with ceramic veneers are indicated. Likewise, areas where space for the outcome already exists without preparation can also be identified.  To ensure adequate incisal reduction, a cylindrical modified bevel bur is used (878 – 016, figure 4a).  This bur can continue be used for axial reduction of tooth structure, but the important thing to consider here is depth control:  Any cylindrical bur with a diameter of 1.4 or 1.6 mm can be used to indicate an incisal depth of very close to 1.5 mm (figure 4b).  After initial depth cuts are made in the facial and incisal portions of the prototype (figure 4c), the extent of the preparation is marked with a sterilized pencil (figure 4d).  Axial preparation is continued through the prototype until the acrylic material is removed to the level of the initial depth cut markings facially.  The incisal edges are reduced to the level of initial notching with the 878 – 016 bur and the acrylic is removed before the preparation design continues with the aid of the incisal reduction guide and facial reduction guide (figure 4e).  Respect should be given to the amount of enamel present for each individual patient, and as much of the preparation as possible should be located in enamel in an effort to conserve tooth structure and maximize adhesive bond strength.

Figure 4e; The completed facial reduction of the maxillary left central incisor.

Figure 4e; The completed facial reduction of the maxillary left central incisor.

Although many preparation designs for ceramic veneers have been proposed, there are some general guidelines to consider.  First, a light chamfer finish-line should be utilized in the cervical and interproximal portions of the preparations.  A round end taper diamond (856L) or modified beveled cylinder (878) in the 1.4 to 2.0 mm diameter range can be used to axially reduce tooth structure and create light chamfer margins.  The finish line should follow the gingival contours and should be placed at or slightly (0.5 mm) below the gingival margin.  In most cases, the finish line should be continuous with the lingual extent of a butt margin on the incisal edge to create a partial or total wrapping of the preparation.  This design will prevent high tensile stresses associated with finish line extension down the palatal surface.[3,4]  Placing the margin on areas with existing static or dynamic occlusal contacts should be avoided.  Second, breaking interproximal tooth contact can create numerous advantages.  By breaking contact, the finish line can be better captured in the final impression, margins of the final restorations will be less visible, and the ceramic technician will be afforded more freedom in approximating adjacent restorations and establishing appropriate tooth contacts (figure 5a).  Although breaking contact is commonly done in cases where a large shade change is desired and in cases of diastema closure, it is not always necessary. If tooth contact is not broken, care should be taken to create an “elbow” underneath the contact area to hide margins that may be visible. Lastly, the preparation should be smooth (figure 5b).  Taking time to polish preparations can offer the operator an opportunity to carefully inspect each preparation for sharp angles or hindrances to path of insertion of the restoration, and alter the prep as needed.

Figure 6; Interproximal caries discovered during initial tooth preparation

Figure 6; Interproximal caries discovered during initial tooth preparation

Of course, these guidelines are theoretical until surgical removal of tooth structure commences. Incidental findings such as decay or existing dental restorations can certainly influence preparation design for ceramic veneers.  In this case, carious lesions were noted on multiple teeth during initial preparation (figure 6).  Moreover, pre-existing restorative material on three of the four treated bicuspids was removed to ensure hard tissue health before proceeding with preparation design.  After further discussion with the patient and laboratory, it was also decided that a conservative crown preparation on the maxillary left lateral incisor would produce a better functional and cosmetic result than an aggressive veneer preparation.

After pre-existing restorative material and caries were removed, tooth preparation was refined and finalized before an impression was made.  As previously stated, the preps were polished during this process to ensure that there were no sharp line angles and no undercuts or impedances to a path of insertion.  A size 0 cord was placed in the depth of the sulcus, followed by a size 1 deflection cord placed more superficial to the sulcular cord.  Desensitizer (Microprime G, Danville Products) was applied to the prepared tooth structure and blotted dry before impressing.  The more superficial cord was removed from the sulcus before the impression was made, and the deeper sulcular cord remained in place to act as a barrier to crevicular fluid or heme (figure 7a, 7b).

The final impression can be taken conventionally by placing a light body PVS wash material around the preparations while a tray is loaded with a heavy body or putty impression material is seated over the teeth to be impressed.  Alternatively, a method where the tray is loaded with putty and a trough is made and then filled with the lighter body wash material before being seated can also be used.  Clearly, an accurate impression is paramount.  In large cases like this, there may be one or two small but important details that are not captured accurately in the total impression.  If this occurs, making a supplemental impression that focuses on the information that needs to be captured more accurately can be made.  The dental laboratory can then make a working die or margin die of one or two teeth without sacrificing the harmony of the composition during fabrication.

After an accurate impression of the preparations is made, an equally accurate impression of the opposing arch is made.  An inter-occlusal record is made with the patient in an upright position.  For this case in particular, each of these steps were imperative, as changes to the occlusal surfaces had been made as part of equilibration treatment.   

Figure 8; Die shade tab photo (photos of ND1 and ND2 were both provided to the dental laboratory)

Figure 8; Die shade tab photo (photos of ND1 and ND2 were both provided to the dental laboratory)

Prior to temporization, die shade photos were taken to communicate with the dental laboratory, as the underlying tooth structure is vital information in cases of shade improvement with ceramic veneers (figure 8). Next, the preparations were spot etched, rinsed, and dried (figure 9a,b) before primer (Optibond XTR Primer, Kerr) was painted on to the preparations and air-dried (figure 9c).  A shrink-wrap technique was used to provisionalize this case.  The silicone putty matrix made from the diagnostic mock-up was again loaded with a provisional material (Visalys Temp, Kettenbach Dental), placed over the prepared teeth, and allowed to auto-cure (figure 9d,e).  The matrix was carefully teased off of the teeth so as not to lift the recently adapted temporary material from the prepared tooth surfaces.  The notches cut into the matrix help limit the amount and severity of flash (figure 9f).  Gross removal of excess material can be accomplished a scaler or similar instrument (figure 9g,h) before rotary instrumentation is used to trim the margins, contour the provisionals, and open gingival embrasures for hygiene purposes.  Some burs to consider for this are the 889-010 diamond separating bur (fine) and the 863-016 diamond flame bur (super fine)(figure 9i,j respectively).  Rotary discs of varying grits (FlexiDisc, Cosmedent Inc., figure 9k) were used to further contour and polish the provisional restorations.  The occlusion is adjusted as necessary.  Once the occlusion is verified, the esthetics are approved and the composition is polished (figure 9l,m).

Figure 9m, The finalized provisional restorations on the preparation day.

Figure 9m, The finalized provisional restorations on the preparation day.

Figure 10; passing super-floss through healthy gingival embrasures post-operatively.

Figure 10; passing super-floss through healthy gingival embrasures post-operatively.

Patients are given hygiene instructions for the provisional phase of treatment. Since the temporary restorations are connected in the shrink-wrap technique, the patient is asked to use super-floss (or a floss threader) twice a day and is shown how to thread the floss through the opened gingival embrasures (figure 10).  The patient is given a Water-Pik and is advised to use it on a relatively low setting (3) for the duration of wearing the temporary restorations.  The patient is asked to brush normally, and is given Chlorhexidine Gluconate 0.12% for nightly use.  Of course, other modalities such as interproximal brushes or rubber tip simulators can be recommended as the idea is to encourage the patient to maintain exceptional gingival health in an effort to create a favorable environment for an adhesive bonding technique at the time of ceramic restoration insertion.

The patient is re-appointed for evaluation 2 weeks after tooth preparation.  Patient feedback about esthetics (including shade), function, and bite comfort are discussed, and necessary adjustments are made.  Once the patient and dentist are satisfied, a high-quality impression of the provisional arrangement is made and sent to the lab to communicate incisal edge position and occlusal scheme.  Select photographs are also taken for adjunct communication tools (figure 11a-h).  In this case, neither the dentist or the patient were happy with the shade of the temporary restorations. New shade tabs of the patient’s desired outcome relative to the current restorations were taken to share with the lab. Finally, the patient is appointed for insertion of the definitive restorations.

It is clear that cases like this are demanding of a clinician’s time, skill, and artistic ability.  Thorough planning and execution, as well as the flexibility and ability to change preparation design intra-operatively, are imperative to success.  Overall, preparations like this can be extremely rewarding, and very fun to do.

Dr. Ryan J. Yakowicz, DDS, FAGD

Dr. Yakowicz practices in the Greater Madison Area of South Central Wisconsin. Having completed over 775 hours of continuing education, his special interests include functionally cosmetic full mouth rehabilitation, TMD and oral-facial pain, and surgical implant placement and prosthetic restoration.

Dr. Yakowicz is currently the president of the Madison Dental Progress Forum Study Club and the Wisconsin Institute for Advanced Dental Education. He is a Fellow of the Academy of General Dentistry, and a member of the American Academy of Cosmetic Dentistry, and the American Academy of Fixed Prosthodontics. Additionally, Dr. Yakowicz participates in research studies for the National Provider-Based Research Network and is an Ambassador to the National Health Service Corps.

References:

[1] IPS e.max Clinical Guide. https://www.ivoclarvivadent.com/en/p/all/products/all-ceramics/ips-emax-dentist/preparation

[2] Magne P, Besler U. Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach. Chicago, IL: Quintessence, 2003: 239-246.

[3]Magne PDouglas WH. Design optimization and evolution of bonded ceramics for the anterior dentition: a finite-element analysis.  Quintessence Int. 1999 Oct;30(10):661-72.

[4]Chai, Sy Yin et al. Incisal preparation design for ceramic veneers. The Journal of the American Dental Association. 2018 Jan;149(1): 25-37.


Start to Finish Veneers: Part 1, Treatment Planning

Many patients present to the dental office seeking cosmetic procedures to improve the appearance of their teeth and smile.  Although teeth contribute to many biologic functions in humans, the importance of teeth as social devices should not be overlooked, as multiple studies relating dental esthetics to oral health related quality of life have correlated poor dental esthetics with psychosocial discomfort, and even poor dental hygiene in certain populations [i,ii].  With the advent of adhesive techniques and advanced dental materials, dentists have the opportunity to improve or enhance dental esthetics in a variety of patient populations using minimally invasive techniques and biomimetic principles.  Through a three-part article, the requisite steps to provide responsible esthetic improvements will be covered in detail.  This portion will focus on treatment planning and case design.

Figure 1; a) The 12 photographic views for AACD accreditation.

Figure 1b-d; b) Duchenne Smile (“E” smile) photo to evaluate lip mobility when muscle recruitment is high; c); Lip in repose photo to evaluate incisal edge position; d) Kois Facial Reference Glasses photo to evaluate maxillary plan and midline.

Figure 1; e) Shade tab photos for patient evaluation.

A 31-year old female presented to the dental office seeking improvements to her smile.  The patient reported a history of orthodontic treatment, and expressed a desire to avoid orthodontic treatment if possible.  Her chief complaint about the appearance of her teeth was the yellow color, despite repeated attempts to whiten with external bleaching.  The patient also reported aversions to the incisal edge discrepancy, the overall length of her teeth, and the distally rotated upper left lateral incisor.

When planning large cases, the first step is to acquire and collate the necessary data.  Photos were taken with a Digital Single Lens Reflex (DSLR) camera and macro lens before impressions were made.  There are 16 photos the author considers essential.  Twelve of the photos are the views required by the American Academy of Cosmetic Dentistry for accreditation [iii,iv] which consist of:

1. Natural Full Face – frontal angle – 1:10 (1:15) magnification

2. Full Natural Smile – frontal angle – 1:2 (1:3) magnification

3. Full Natural Smile – right lateral angle – 1:2 (1:3) magnification

4. Full Smile – left lateral view – 1:2 (1:3) magnification

5. Upper and lower teeth slightly parted – frontal view – 1:2 (1:3) magnification

6. Upper and lower teeth slightly parted – right lateral – 1:2 (1:3) magnification

7. Upper and lower teeth slightly parted – left lateral – 1:2 (1:3) magnification

8. Maxillary anterior in view only – frontal view – 1:1 (1:1.5) magnification

9. Maxillary anterior in view only – right lateral – 1:1 (1:1.5) magnification

10. Maxillary anterior in view only – left lateral – 1:1 (1:1.5) magnification

11. Maxillary arch – occlusal view – 1:2 (1:3) magnification

12. Mandibular arch – occlusal view – 1:2 (1:3) magnification

In addition, four adjunct photos are taken:

13. Duchenne Smile or Exaggerated (“E”) Smile photo (to evaluate lip mobility during a genuine smile)

14. Lip in repose (lip at rest) photo (to evaluate incisal edge position)

15. Kois Facial Reference Glasses with retraction (to identify any cants or midline discrepancies)

16. Shade tab photos (to assess patient preference for final shade)

(figure 1a-e)

The goal of the Duchenne Smile photo (“E” or Exaggerated Smile photo) is to activate the zygomatic major muscle and the orbicularis oculi muscle to provide perspective on tooth display that may only occur during a genuine smile (which is often difficult to replicate in the dental office). This photo is achieved by simply asking the patient to produce the biggest smile possible. Although there is variability in lip form, the lip in repose photo should focus on the canine, as Dr. Carl Misch concluded the canine exposure dimension relative to the upper lip in repose can be used to predictably assess anterior incisal edge position [v]. The patient is asked to say “Emma” and the photo is captured after the last syllable. The Kois Facial Reference Glasses are outfitted with horizontal and vertical reference planes and offer a chance to evaluate the current maxillary occlusal plane for cants that may need to be corrected, as well as the opportunity to correct midline cants or discrepancies. Shade tab photos are an excellent communication tool for the patient, laboratory, and dentist when determining the final shade in the definitive restorations. The shade tab should be aligned vertically and on the same plane as the teeth to be modified, and the shade tab label should be visible in the photo.

After photos are taken, high quality impressions are made (or full arch intra-oral scans are taken).  The importance of taking impressions AFTER high quality photographs are taken should not be overlooked, as residual impression material can negatively affect otherwise excellent photographs. The impression technique used here utilizes a PVS heavy body putty and a PVS light body wash to capture as much detail as possible.  Taking an inter-occlusal record can be challenging in some cases, and it is important to consider that certain patients may need to be treated to an orthopedically stable temporomandibular joint position, or Centric Relation Position, instead of an inter-cuspal position. If this is necessary, the most stable position of the joint should be determined and registered prior to restorative therapy.  Fortunately, this patient had no signs of Temporomandibular Joint Dysfunction (despite evidence of occlusal interferences), and the inter-cuspal position was accepted as the treatment position.

Figure 2; Evaluating gingival heights and contours.

Currently, Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) technologies are utilized in the majority of the author’s case planning, and have almost entirely replaced analog diagnostic wax-ups.  For this case, definitive casts were made from the PVS impressions and mounted on a semi-adjustable articulator (Panadent).  The casts and mounting were scanned into 3Shape CAD/CAM software.  From here, the digital design process could commence.  Although the main indication for veneers in this case was a patient desire for whiter teeth that were resistant to external bleaching, the goals of this case design were also based on smile design and dental esthetic principles [vi].  The digital “wax-up” begins with the maxillary central incisors, as it is essential that these teeth are symmetrical. To achieve this, it is necessary to first evaluate gingival health, zenith heights, and contours, as the gingival shroud will frame the teeth and subsequently the smile. For this patient, it was determined that the gingival levels and contours were balanced and in an acceptable position to maximize smile design principles (figure 2)[vii,viii]; no gingival plastic surgery would be required.  Next, the design focused on individual tooth proportion and relative tooth dimension. The pre-operative dimensions of the central incisors were 9 mm in height and 9 mm in width (a 100% width to height ratio), giving them a square appearance that lacked femininity. Having accepted the location and shape of the gingival tissues, length was added to the incisal edges of the maxillary central incisors so the new height would be 10.5 mm, while the 9 mm width was maintained (producing a more normative width to length ratio of 86%)[ix].  After the central incisors were designed, relative tooth dimensions and appropriate axial inclinations were applied to the lateral incisor and canine designs. Specifically, the malposition of the maxillary left lateral incisor was corrected in the CAD/CAM design, making light of an important part of the planning process: the data acquired from the plan will help dictate the eventual preparation design.  In this way, conservative and minimally invasive preparations to achieve the final outcome can be executed relative to the initial design.  This is a special consideration when instant orthodontics are to be performed using direct or indirect restorative materials, as areas where more or less tooth removal is required can be identified by overlaying the initial model scan and the idealized CAD/CAM design (figure 3a-b). Finally, the upper bicuspids on each side of the arch were included in the design to create harmony throughout the smile composition and control the patient’s buccal corridor. After completion, the digital design can be stitched to a digital photo to offer a prospective image approximating the appearance of the proposed restorative design in the patient’s smile (figure 4).

Figure 3a-b; The digital wax up overlayed on the pre-operative scan showing the difference in pre-operative tooth position and the proposed changes from a) an occlusal view and b) a frontal view.

Figure 4 ; A prospective image approximating the appearance of the proposed restorative design digitally integrated into the patient’s smile

Figure 4; A prospective image approximating the appearance of the proposed restorative design digitally integrated into the patient’s smile

The design is then manipulated in the digital space to evaluate the case from different perspectives. This allows fine tuning of intricate details related to tooth form such as facial line angle position, embrasure symmetry and balance, and even surface variation and texture [x]. Next, functional considerations are addressed.  The patient’s static and functional occlusion is evaluated and refined using the digital articulator.  For this case, canine rise was an achievable goal.  Additionally, it was discovered that the patient had multiple occlusal contact on inclined planes and functional interferences when excursive movements were performed in the digital work-space on the programmed digital articulator (figure 5).  This finding was confirmed clinically and it was determined that equilibration would be planned and performed prior to tooth preparation and the equilibration would be refined after delivery of the definitive indirect restorations.

Figure 5; Static and functional occlusal markings for each arch, clinically and digitally.

After the case design is finalized, a model of the desired case outcome is printed using a 3D printer.  This model is important in fabricating deliverable items that are essential to not only a good case outcome, but to a minimally invasive preparation design that will encourage biomimetic restoration of the teeth.  First, a facial reduction guide is made.  When the teeth included in the treatment plan are prepared for veneers, this index provides the operator a reference to areas where more or less reduction of tooth structure is necessary as it relates to the thickness of the restorative material.  For this case, the goal will be to produce thin lithium disilicate (IPS eMax, IvoclarVivadent) veneers that will range in facial thickness from 0.5 mm to 0.7 mm [xi].  When compared to the pre-operative condition, the facial reduction guide aids the clinician in planning removal of tooth structure in a way that is conservative and consistent with the desired outcome.  Additionally, an incisal reduction guide is made to offer a preparation reference that will replicate the final incisal edge positions of the restorations and ensure the ceramic technician has space to create incisal characteristics such as translucency and microanatomy.  For this case, the desired thickness of restorative material at the incisal edge is 1.5 mm.  Lastly, a fairly rigid silicone index of the model is made from the printed model of the mock-up [xii].  Not only will this index be used to provisionalize the case with a working prototype, but the index can offer a preliminary evaluation of the case outcome and offer an adjunct method for determining the necessary amount of facial reduction (figure 6a-f).  To transfer the mock-up, the index is loaded with an auto-cure temporary composite acrylic material (Visalys Temp, Kettenbach Dental) and overlayed onto the existing teeth with no preparation or adhesive.  The material is allowed to cure before the index is removed and gross excess material is trimmed.  At this time, the prototype is evaluated by the clinical and the patient.  Important photographs are taken evaluate the proposed design and to ensure the midline is perpendicular and aligned with the face.  Tooth shape, length, proportion, and axial inclination is also evaluated.  Shade can be roughly estimated at this time, as many provisional materials come in esthetic shades.  After the prototype design is validated by the operator and patient, the preparation phase of treatment can begin (figure 7a-d).

Figures 6a-f; a) A facial reduction guide made to the proposed result; b)The facial reduction guide compared to the pre-operative model; c) An incisal reduction guide made to the proposed result; d) View of the proposed changes to the current incisal edges; e) A silicone matrix to transfer the mock-up (pre-operatively and for provisionalization); f) Wedges cut into the gingival embrasure spaces of the matrix to provide a spillway for excess provisional material.

d

d

Figure 7a-d; a) Full Smile – left lateral view – (1:3) magnification; b) Natural Full Face – frontal angle – 1:10 (1:15) magnification; c) Kois Facial Reference Glasses photo with mock-up in place; d) Upper and lower teeth slightly parted – frontal view – 1:2 (1:3) magnification

Integrating appropriate patient data and communicating appropriately with a capable dental laboratory are paramount to achieving ultimate success in cases dealing with functionally esthetic corrections and smile design.  Careful thought must be given to the design process and dentist must avoid a “prep and pray” modality of rendering treatment. Involving the patient in the process is recommended, as patient input offered in the planning stages of treatment can not only increase overall satisfaction with the outcome, but can save expense and time in the restorative stages of treatment.  Moreover, thorough planning with all parties involved (dentist, technician, patient) can be very rewarding and make planning cases like this extremely fun!

Dr. Ryan J. Yakowicz, DDS, FAGD

Dr. Yakowicz practices in the Greater Madison Area of South Central Wisconsin. Having completed over 775 hours of continuing education, his special interests include functionally cosmetic full mouth rehabilitation, TMD and oral-facial pain, and surgical implant placement and prosthetic restoration.

Dr. Yakowicz is currently the president of the Madison Dental Progress Forum Study Club and the Wisconsin Institute for Advanced Dental Education. He is a Fellow of the Academy of General Dentistry, and a member of the American Academy of Cosmetic Dentistry, and the American Academy of Fixed Prosthodontics. Additionally, Dr. Yakowicz participates in research studies for the National Provider-Based Research Network and is an Ambassador to the National Health Service Corps.

References:

[i] Silvola AS, Varimo M, Tolvanen M, Rusanen J, Lahti S, Pirttiniemi P. Dental esthetics and quality of life in adults with severe malocclusion before and after treatment. Angle Orthod. 2014 Jul;84(4):594-9.

[ii] Solomon D, Katz R, Bush A, Farley V, McGerr T, Min H, Carbonella A, Kayne J. Psychosocial impact of dental esthetics on periodontal health, dental caries, and oral hygiene practices of young adults. General Dentistry. 2016 March/April; 64 (2): 44-50.

[iii] American Academy of Cosmetic Dentistry. “A guide to accreditation photography: Photographic documentation and evaluation in cosmetic dentistry.” Madison, WI: 2009-2015.

[iv] Terry DA, Geller W. Esthetic & restorative dentistry: material selection & technique. Chicago: Quintessence Pub. Co., 2013: 553-572.

[v] Misch CE.  Guidelines for maxillary incisal edge position-a pilot study: the key is the canine.  J Prosthodont. 2008 Feb; 17(2): 130-134.

[vi] Magne P, Magne M, Besler, U. Natural and restorative oral esthetics. Part 1: Rationale and basic strategies for successful esthetic rehabilitations. Journal of Esthetic Dentistry 1993; 5: 161-173.

[vii] Rufenacht CR. Fundamentals of Esthetics. Berlin: Quintessence, 1990: 67 - 134.

[viii] Goodacre CJ. Gingival esthetics. Journal of Prosthetic Dentistry 1990; 64: 1-12.

[ix] Sterrett JD, Oliver T, Robinson F, Fortson W, Knaak B, Russell CM.  Width / length ratios of normal clinical crowns of the maxillary anterior dentition in man. Journal of Clinical Periodontology 1999; 26:153-157.

[x] American Academy of Cosmetic Dentistry. “A guide to accreditation criteria: Contemporary concepts in smile design.” Maidson, WI: 2014.

[xi] “IPS eMax: Clinical guide.” Ivoclar Vivadent. (file:///C:/Users/ryany/Downloads/IPS+e-max+Clinical+Guide%20(1).pdf)

[xii] Magne P, Besler U. Bonded Porcelain Restorations in the Anterior Dentition: A Biomimetic Approach. Chicago, IL: Quintessence, 2003: 239-246.