Dr. Larry R. Holt, DDS

Dentists face numerous challenges associated with full-mouth extractions and arbitrary placement of 

. Solutions can result in less than desirable physical properties of the final restoration, and the resulting restorations may require repeated service and possibly exhibit longevity issues. Compromises often lead to disappointments, which is why planning in consultation with the dental 

 is so critical to long-term treatment success.

 and the Stratos Articulator system enable dentists and their laboratories to provide patients with predictable denture setups for try-in, and ultimately, esthetic dentures that fit and function comfortably. Combined, the two products work together systematically, with BlueLine tooth mould selection focusing on patient characteristics and the best occlusal scheme identified by the dentist; working with the Stratos Articulator is subdivided into efficient and accurate steps, with its magnetic flat table and quick set-up template creating a functional and accurate prosthesis time and again.


	A female patient presented for an initial clinical consultation and patient interview that revealed that she was extremely dissatisfied with the discomfort, denture instability, and esthetics of her treatment dentures that were delivered at the time of extractions and implant placement (Fig. 1).
	 

Her lips were over supported by dentures that had inappropriate tooth moulds and excessive display of gingival acrylic superior to the maxillary anterior teeth. Pretreatment photographs of the patient were requested. Evaluation of 20-year-old photographs revealed a very narrow arch form with long, narrow teeth. The patient had a highly mobile upper lip with an elevated high lip line (Fig. 2).

The implants were placed before any treatment planning was performed, and they were uncovered after final impressions in custom trays were taken. The laboratory was enlisted several months after surgery, and bite rims over stabilized base plates were fabricated. The original treatment denture was based on the compromised, terminal dentition, and the ravages of periodontal disease and tooth loss resulted in splayed, malpositioned teeth (Fig. 3).


	To shape the maxillary bite rim, the 20-year-old photograph was used in the operatory. This narrowed arch form would have been difficult to identify without referencing the photograph.
	The bite rims were properly contoured for tooth display, lip support, and vertical dimension (e.g., phonetics and “S” clearance). High lip line and midline were scored onto the rim.

A facebow transfer and centric relation bite record were recorded, a complete prescription was written, and all clinical records returned to the laboratory.

The patient’s face was measured, and a tentative tooth mould was selected. The patient wanted bright, white teeth, as well as a palateless denture. Measurement of restorative space from ridge crest to occlusal table of the bite rim was the first evidence that implant position would create a challenge (Fig. 4).

At the laboratory, models were mounted on a Stratos Articulator using clinically generated records. Final tooth selection was based on the old photograph and the clinical records provided. BlueLine tooth mould A25/N5 was selected as the best available choice to match the patient’s natural teeth.

A traditional full balance with the anterior teeth slightly out of contact was the occlusal scheme selected.

In the interim between maxillo-mandibular relations and try-in, the implants were uncovered and healing abutments placed. A wash of Fit Checker (GC America) fast setting silicone indicator was placed to “spot” the implant locations (Fig. 5).

The patient’s request for a palateless denture, combined with the limited restorative space, led to the decision to use metal framework reinforced dentures. It was further determined to use the lowest possible profile attachments available, because space was extremely limited for attachment placement (Fig. 6). Ivocap processing was ordered and the case was submitted for processing.
	The first try-in was a success. The patient stated, “I never thought I could look normal again” (Fig. 7).

The processed dentures were provided by the laboratory, along with a Stratos Articulator and Siltech putty (Ivoclar Vivadent) models of the denture bearing areas, which were used for a clinical remount of the final prostheses. The putty model provided an accurate and resilient, retentive remount.

The dentures were tried in initially before removing the healing caps to verify there would be no interference with complete seating of the appliances during the delivery process. A mix of Fit Checker silicone indicator was placed into the denture to check for interferences (Fig. 8). The occlusion was evaluated, and clearance was confirmed.

Each Rhein 83 Equator abutment was torqued into place, and clearance for the abutments and retentive elements was confirmed by trying in pairs. Chairside pickup of the retentive elements was accomplished using Quick Up (VOCO) dual cure material, which is convenient for this procedure. The kit comes with a Fit Test material used for evaluating clearance over and around the retentive caps and which was used to evaluate each pair of abutments.

Note: It would be nearly impossible to evaluate all four upper attachments simultaneously due to possible incomplete seating of the denture base caused by premature contact of components with the denture base. The successful use of this material, plus constant evaluation of complete interdigitation of teeth, ensured that the dentures were fully seated prior to chairside attachment pickup. These steps were critical to maintain the accuracy of fit, final esthetics and function of the delivered appliances.

All retentive caps were micro-abraded with 50 micron aluminous oxide, then coated with adhesive, along with the denture acrylic “wells” into which the retentive caps were to be captured.
	The retentive caps with black processing elements were then placed onto the abutments in the patient’s mouth, and a dental assistant was ready to maintain a dry field during the seating process.

The dual cure pick-up material was injected into the “wells,” with care taken not to overfill these retentive areas (Fig. 9).

The appliance was then seated into the mouth with the opposing appliance already in place, and the patient was instructed to close into complete closure. The occlusion was evaluated as a final check for full seating.

All retentive elements were picked up, and the occlusion remained consistent throughout the procedure. All black processing caps were removed and replaced with yellow retentive caps, which were extra soft and least retentive (Fig. 10).

The dentures were replaced, bite registration taken and confirmed on the articulator, and minimal occlusal adjustment was necessary.

The patient was checked for any discomfort or other comments, and given a mirror and the opportunity for final evaluation (Fig. 11).


	This case reveals a common challenge encountered by laboratories. Lack of case planning and arbitrary implant placement often create nearly impossible fabrication scenarios. This case failed to meet the minimum requirements for the restorative space needed for typical case fabrication.

The original intent of the restorative dentist was to use Zest Locator attachments. The ubiquitous Locator attachment is contraindicated in this case due to insufficient restorative space in which to place its retentive components. In addition, the patient had exceptional esthetic expectations exacerbated by her highly mobile lip and high smile line.

Technicians are an integral part of the implant restorative team who can provide critical information regarding tentative case design and subsequent implant placement decisions. The restorative team, comprised of the restorative doctor and his laboratory technician, are responsible for defining final treatment goals. The results of proper case planning and work-up are then communicated to the surgical team and must include precise implant locations and any required boney/soft tissue modification necessary to facilitate restorative procedures.

This information can be used by the surgical team for cone beam imaging through fabrication of scan appliances based on the restorative treatment plan. If imaging results contraindicate desired locations for precise implant placement, then it is up to the surgical team to request compromise/alternate implant locations. Under no circumstance should the surgical team arbitrarily substitute locations without prior approval by the restorative team. It’s often helpful for a member of the restorative team to attend the implant surgery.

Laboratories are incredibly innovative. They can often engineer solutions to very challenging situations. Unfortunately these solutions can result in less than desirable physical properties of the final restoration. Resultant restorations may require repeated service and possibly exhibit longevity issues. Compromises often lead to disappointments, which is why planning is so critical to long-term treatment success. Short-term convenience should never outweigh the advantages of planned, long-term success.

The presented case was resolved using innovative laboratory concepts. Alternate retentive components and metal reinforcement of the denture acrylic  provide a strong, predictable result. Thanks to this innovative use of available materials, this challenging case was successfully resolved.

Information provided by Ivoclar Vivadent Inc. 

Articles

Dentists face numerous challenges associated with full-mouth extractions and arbitrary placement of dental implants. Solutions can result in less than desirable physical properties of the final restoration, and the resulting restorations may require repeated service and possibly exhibit longevity issues.

How to: Correct unplanned dental treatment

Commonly encountered challenges faced by laboratories when fabricating implant-supported dentures are lack of case planning and arbitrary implant placement that often create nearly impossible fabrication scenarios. For these reasons, technicians should be included as an integral part of the implant restorative team to provide critical information regarding tentative case design and subsequent implant placement decisions. This communication should provide precise locations of implants and any required boney/soft tissue modification necessary to facilitate restorative procedures.

Such information can be used by the surgical team for cone beam imaging through fabrication of scan appliances based on the restorative treatment plan. If imaging results contraindicate desired locations for precise placement of implants, then the surgical team can request compromise/alternate implant locations. Arbitrarily substituting locations without prior consultation contributes to fabrication challenges.

 Injection system is an innovative controlled heat and pressure polymerization-based system that eliminates inaccuracies in fit caused by chemical shrinkage of polymethyl methacrylate. Demonstrating a high degree of polymerization and a strong bond to resin teeth, the system compensates for acrylic shrinkage by continuously flowing the exact amount of material needed into the flask through pressure injection, enabling fabrication of high-quality dentures that fit well and are comfortable. The material is distributed in pre-dosed capsule form, so no mixing or dosing is required.

The SR Ivocap polymerization system also reduces the risk of system-induced increases in vertical dimension and spherical deformation, which eliminates the need for time consuming occlusal adjustments. The risk of fracture also is greatly reduced because the system promotes homogeneity, yet the denture base material remains highly polishable, maintainable and resistant to plaque accumulation.

Upon presentation, this case failed to meet the minimum requirements for the restorative space required for typical denture fabrication. The intent of the restorative dentist was to use “Locator” attachments (Zest Anchors). The ubiquitous Locator attachment is contraindicated in this case because of insufficient restorative space in which to place its retentive components. In addition, the patient had exceptional esthetic expectations exacerbated by her highly mobile lip and high smile line. Because the dentist and technicians were attempting to optimize an already compromised case, it was imperative that a logical, methodical and innovative mindset be maintained.

Because the surgical team placed the implants prior to any treatment planning, they were uncovered after final impressions were taken, which required determination of implant head location relative to the crestal emergence. The dentist used a silicone material in the anticipated areas, with indentations representing the final attachment placement.

 Rhein 83 Equator attachments were selected because of their low vertical profile, which is the lowest available. To relay this information to the master casts, cotton candy flavor lip gloss was used as reverse indicating paste 

. These indicators marked the casts, and the highlighted areas were subsequently identified with a red marker.

 The Rhein 83 Equator metal keepers were then fixed to the models 

, and once satisfied with the estimated locations, they were surrounded with 1 mm thick partial saddle wax to anticipate deviations in positioning assessment

 The wax try-in was returned from a successful clinical evaluation and patient approval, and a series of Sil-tech indices (Ivoclar Vivadent) were developed to maintain the exact position of vertical dimension of occlusion and tooth alignment, because these would be used to reset the teeth to the master casts with the Rhein 83 Equator attachments in place 

. This procedure was critical to the final prosthesis because transferring this information cannot be predictably duplicated without this method.

 (Ivoclar Vivadent) denture teeth were selected, because of their anatomical similarity to natural dentition and multilayered acrylic, true shade processing technique 

 The indices were placed without the denture teeth, and the limited space available for the final prosthesis was recognized 

 A cast mesh retention element also needed to be incorporated to the appliances to ensure stability and strength. In situations where space is at a premium, the mesh must be modified to be as strong as possible without interfering with final function and esthetics.

 The red marker areas were cut back to allow space for the denture teeth, without reducing too much of the cervical areas 

 The teeth were reset to the master casts over the Rhein 83 Equator attachments and the cast mesh frames, then returned to the Stratos mountings for final evaluation.

 The vertical pin setting was checked for accuracy, and the wax-ups were sealed to the casts 

. The Stratos Articulator was used for its range of use in both removable and fixed situations.

 Processing was accomplished with the Ivocap technique, which minimizes any acrylic processing distortions and provides the most dense and accurate acrylic available. This technique is a continuous injection process that ensures a ready supply of material, because polymerization shrinkage is initiated in the curing process, thus resulting in a predictable outcome that translates into less finishing and polishing effort.

 The overdentures were devested, revealing waxed contours faithfully replicated 

 The dentures were remounted to the Stratos Articulator, and the vertical pin was verified for VDO stability 

 The occlusion was equilibrated for exquisite stability and function, and the Feeding Sprues removed.

 The dentures were subsequently removed from the casts and finished and polished for delivery.

 Spaces were provided in the intaglio surface for the Rhein 83 Equators to be picked up chairside 

This case reveals a common challenge encountered by laboratories. Lack of case planning and arbitrary implant placement often create nearly impossible fabrication scenarios. This case failed to meet the minimum requirements for the restorative space needed for typical case fabrication.

Laboratories are incredibly innovative. They often can engineer solutions to very challenging situations. Unfortunately these solutions can result in less than desirable physical properties of the final restoration. Resultant restorations may require repeated service and possibly exhibit longevity issues. Compromises often lead to disappointments, which is why planning is so critical to long-term treatment success. Short-term convenience should never outweigh the advantages of planned, long-term success.

The case presented in this article was resolved using innovative laboratory concepts. Alternate retentive components and metal reinforcement of the denture acrylic provided a strong, predictable result 

. Thanks to this innovative use of available materials, this challenging case was successfully resolved.

Andre Theberge RDT, CDT, is Laboratory Manager at Drake Precision Dental Lab in Charlotte, N.C., and is responsible for all areas of fixed and removable prostheses. After attending dental laboratory college at George Brown College in Toronto, he began his career 30 years ago as a private technician and subsequently established commercial dental labs in the Hamilton area. He was president of the ADTO in Canada. Andre received his RDT designation in 1988 and his CDT in 1998.

Larry R. Holt, DDS graduated from the University of North Carolina School of Dentistry in 1978. He has enjoyed thirty years of private practice in North Carolina. After retiring from private practice, he joined Drake Precision Dental Laboratory as Director of Clinical Education and Research. Dr. Holt is an Adjunct Professor at UNC School of Dentistry, and a Clinical Associate Professor at Medical College of Georgia.

Commonly encountered challenges faced by laboratories when fabricating implant-supported dentures are lack of case planning and arbitrary implant placement that often create nearly impossible fabrication scenarios. For these reasons, technicians should be included as an integral part of the implant restorative team to provide critical information regarding tentative case design and subsequent implant placement decisions.

Fabricating implant-supported dentures

	There’s potential for confusion among practitioners because of the abundance of currently available materials and techniques. Many excellent materials are available, however they all require meticulous attention to clinical technique to record the accuracy necessary for fabrication of well-fitting restorations.

	Meticulous preparation techniques and respect for biologic principles create an environment from which an excellent impression can be taken. Scrupulous gingival retraction, hemostasis and a coordinated dental team provide the circumstances from which successful dental impressions can be accomplished. All of these clinical efforts are accentuated with the use of a superior impression material.

 impression material and a clinically predictable technique can capture excellent marginal detail.

	Identium is a Vinylsiloxanether (VSXE), a proprietary formulation that boasts a successful combination of the attributes of Vinyl Polysiloxane and Polyether impression materials while eliminating many of the shortcomings of each. Identium overcomes the unpleasant taste associated with Polyether materials. It has no perceptible taste for all practical purposes. Hydrophilic properties of Identium are superior when compared with traditional VPS materials. Viscosity of Identium is similar to polyether as observed clinically. Tray removal is vastly improved over polyether. It’s extremely hydrophilic and has excellent flowability. These traits are highly desirable for clinically successful results.

	Identium is available in heavy body, medium body and light body viscosities. It can be delivered by typical “gun” delivery systems or from Kettenbach’s Sympress automix machine. The materials can be considered universally applicable to all restorative procedures. It’s available in a regular set and a fast set formulation. Long working times with a relatively short intraoral setting time are unique to Identium.

	Impression taking is an art form. Success is derived through a meticulous manipulation of hard and soft tissues. It’s imperative that initial gingival health is confirmed. In the presence of soft tissue disease, no restorative procedure is totally predictable.

 Soft tissue management programs either by general dentist or by a periodontist are highly recommended.
	Clinicians are urged to fully understand the relationship between free gingival crest, bony crest and restoration margins. This is the genesis of the term “biologic width.”

 The relationship of margin location relative to bone level is critical. In a typical bony crest to gingival crest relationship, there is a 3 mm zone in which soft tissue structures exist. The first millimeter is composed of connective tissue fibers, second level is epithelial attachment and the final millimeter of the soft tissue apparatus is the gingival sulcus.

	This characteristic is shared by 85% of the population.

 Astute restorative practitioners routinely sound to bone from free gingival crest to bony crest to recognize this critical relationship. The literature is replete with articles that confirm that ideal margin placement is supragingival.

 Unfortunately, clinicians are faced with intracrevicular margin placement on a daily basis.

	Esthetic expectations, retention-resistance form requirements, depth of dental caries and extension of previous restorations all require clinicians to place restorative margins within the gingival complex.

 It’s vital that restoration margins don’t invade the fragile epithelial attachment complex and certainly not into the connective tissue attachment. This leaves clinicians approximately 1 mm of crevicular space into which margins can be extended.

	It’s the author’s opinion that 0.5-1.0 mm is the ideal depth of placement for intracrevicular margination. Violation of this principle can result in potentially unpredictable results. Tissue redness, hypertrophy and possibly gingival recession can occur when the biologic width is abused. Any abuse to gingival tissues during tooth preparation will result in some form of gingival inflammation and subsequent unpredictable gingival response to final restorations.

Avoid rotary gingival curettage, electrosurgery, laser surgery and any other significant gingival manipulation on the day that final impressions are to be taken (Fig. 1). It’s especially important to follow this premise in the esthetic zone where even the slightest inflammation or recession of gingival tissue is immediately evident to even the casual observer.

Complete tooth preparation to the free gingival crest following the natural gingival scallop prior to any gingival retraction. Failure to follow the scallop can result in violation of interproximal biologic width. Once the decision is made to place an intracrevicular margin, the clinician should place a size 000 braided retraction cord to the depth of the gingival sulcus (Fig. 2). Great care should be taken not to violate the epithelial attachment during this gingival manipulation. Observe the relationship between the prepared margin and the free gingival crest. It’s desirable for that relationship to change very little during initial cord placement. 

 If the gingival crest moves a millimeter or more away from the prepared margin, don’t take an impression at this appointment. This is a telltale sign of a low crest relationship between gingival crest and bony crest.

Cautiously extend the marginal scallop into the gingival crevice 0.5-1.0 mm. Don’t extend any deeper to avoid violation of biological preparation principles. At this point the decision must be made as to take an impression or not.

Place a size 1.0 cord into the sulcus following final margin placement if final impressions are to be taken. This cord must be totally visible to assure satisfactory gingival retraction. Most clinicians will select a retraction cord saturated with hemostatic solution for final retraction. Aluminum chloride or ferric sulfate formulations are typically used for this purpose. If gingival tissue overhangs the cord superiorly in any location it will block the ingress of impression material during impression injection phase. The desirable result of retraction cord number two is a very clear differentiation between tooth margin, retraction cord and gingiva (Fig. 3). This so-called two-cord technique has been successfully used for many years. It provides adequate retraction, maintains retraction and provides hemostasis.

An alternate chemomechanical retraction technique also can be considered for preparation and final gingival retraction. Traxodent (Premier) can be injected into the gingival sulcus prior to final margination following initial 000 cord placement. This material will absorb sulcular fluids and create a chemomechanical retraction of the sulcular walls, while providing hemostasis. This action can be enhanced by placing Premier Retraction Caps that fit over prepared teeth and pressing the Traxodent into the crevice. Traxodent requires 2-3 minutes to react. Air water spray will remove the Traxodent and reveal a retracted sulcus into which margins can be extended. Once final margin placement is accomplished this same Traxodent technique can be used in lieu of a final cord in the “two-cord technique” (Figs. 4, 5 & 6).

Impression tray selection depends upon the number of teeth being treated, location of the prepared teeth, position of adjacent teeth, and patient’s occlusal relationship. The quadrant tray/dual arch tray provides a viable technique for single and two unit impressions (Fig. 7). Dental laboratories report these trays to be the most commonly used.

 Studies reveal this technique to provide predictable accuracy when practiced according to appropriate clinical guidelines.

 Quadrant trays should be avoided when not bounded by intact teeth. A canine should be present in this technique and bridges are contraindicated.

 Communication with laboratory managers reveals substantial departure from these principles.

Full-arch impressions are a desirable option. Technicians can reference the contralateral side for comparison so as to provide bilaterally consistent tooth form. A full complement of teeth provides a more consistent centric occlusion with mounted models than a quadrant. It’s far easier for a laboratory technician to mount full arch casts than quadrant impressions. This accuracy of mounting will be reflected in the occlusal accuracy of final restorations. Clinical trial shows that Identium performs its best when used in a closed stock tray or custom tray for multiple units and for full arch impressions (Fig. 8).

	Identium flows well into the prepared gingival crevice and creates excellent wetting of the overall tooth surface (Fig. 9). The final impression quality obtained with Identium is crisp and highly defined. Laboratory feedback is very positive. The material is durable and holds up to multiple pours without macro degradation. It’s the clinical experience of the author that restorations fabricated from Identium impressions exhibit excellent marginal adaptation.

 There’s potential for confusion among practitioners because of the abundance of currently available materials and techniques. Many excellent materials are available, however they all require meticulous attention to clinical technique to record the accuracy necessary for fabrication of well-fitting restorations.