Unique Solution for Porcelain Fracture: A Case Report

You’ve completed a case with multiple fixed bridges using PFM or porcelain-fused-to-zirconia (PFZ) and your patient comes in for routine recall visits. All the planning and hard work you did looks good at every recall. Then, one day the phone rings, and your patient says, “My front bridge is cracked.” When you’re told who called, and remember that the work included a PFZ fixed bridge from Nos. 6 to 11, completed just more than one year ago, your jaw drops. What could possibly have happened? Everything was looking so good at the last recall appointment!

When this patient arrived at our office with fractured porcelain at the incisal edge and facial of tooth No. 9 (Figure 1), I asked some questions to ascertain the cause of the fracture. Was it a hard nut, a chicken bone, a spare rib, or an accidental hit on the bridge with a fork or spoon, etc? Was he wearing his nightguard regularly? He said yes. I began to think, is the patient telling me the whole truth? All this went through my mind, as a treatment decision that would solve this challenge had to be made.

Figure 1. The fractured porcelain on the upper left central incisor (tooth No. 9).	Figure 2. Post-op photo of the first repair attempt of fractured porcelain on No. 9.

Figure 4. Unaesthetic veneers at age 41.

I told my assistant what to prepare, and we did a porcelain repair using the Porcelain Repair Kit (Kuraray America), which would ordinarily provide a reasonably strong and reliable repair solution in many cases (Figure 2). The occlusion was checked carefully in all positions, including protrusive and lateral excursions, just as was done when the bridge was originally delivered; it was deemed free of any unwanted occlusal or excursive interferences. We were careful to advise the patient that a composite resin-to-porcelain repair in this case might present a challenge because the fracture was at the biting edge of his front tooth. Precautions were given about what to try to avoid biting/eating, and then the patient was dismissed.

A few weeks later, the patient called to say, “The repair that Doc did broke off.” He returned to the office and we repaired it again, carefully checking every possible occlusal and excursive position. (At this point, if one is inclined to say a little prayer, maybe that should be in the protocol too.)

Several weeks later, another phone call came in and, yes, the second repair did not hold. Now what? The patient arrived and we did the repair once again, although this time the area needing coverage was bigger than the last time. I told the patient I would speak with my dental technician and try to figure out another approach. Obviously, I knew we that were going to have to make a new bridge, but what could we do differently the next time to avoid future problems for this patient?

HISTORICAL BACKGROUND OF THE CASE
In order to close spaces post-orthodontic treatment when this patient was in his late teens and fully grown, we had placed porcelain veneers on teeth Nos. 6 to 11. Through the course of many years, he had worn down his dentition severely (Figure 3) and, at the age of 41, he had decided to do the full rehabilitation he needed for functional and aesthetic reasons (Figure 4). We had discussed this option at many of his recall visits leading up to his decision.

Before I dismissed the patient after the second repair, I had asked him to stand up so I could observe his jaw movements while standing. (This was requested because he stood while doing his tasks at work.) He demonstrated a latero-protrusive movement that went far beyond any motion he had demonstrated previously. He told me that he realized he was under constant pressure at work, and that he would catch himself “playing” with his teeth. I finally found the probable cause for fracturing the edge and facial of No. 9; an extreme crossover movement of No. 9 that occurred during daytime grinding while his nightguard was not being worn. Years ago, he had reported that his uncle and father had both ground their teeth “down to stubs,” which became a motivation for him to wear his nightguard regularly for many years. However, that afforded him no protection during the day.

“Bruxism has 2 distinct circadian manifestations: it can occur during sleep (indicated as sleep bruxism) or during wakefulness (indicated as awake bruxism).”¹ Awake bruxism is thought to be usually semivoluntary, and often associated with stress caused by things such as family responsibilities/problems and/or work pressures.²

This patient was extremely anxious, hyperactive, and shook his leg frequently (although restless leg syndrome was never formally diagnosed). I thought he might be an example of a genetically programmed neurologic grinder; something I had learned at a course taken at the Kois Center in Seattle. I dug out my notes from the course (Functional Occlusion II: Complex Restorative Management) and a picture started to emerge. Among the characteristics of patients with occlusal parafunction, as described by Dr. John Kois, are bruxism, anxiousness, hyperactivity, and abnormal posturing.³ This patient exhibited these characteristics as well as cheek and nail biting, also often found in patients with daytime bruxing.²

Original Full Rehabilitation: Clinical and Dental Lab Protocol
There are many steps and nuances in this case; however, the main purpose of this article is to demonstrate a method for dealing with severe bruxism that will assist in avoiding porcelain fractures in cases such as these. Therefore, treatment done prior to the second cuspid-to-cuspid fixed partial denture (teeth Nos. 6 to 11), will simply be summarized rather than be described in great detail.

When we began the rehabilitation, a comprehensive exam was performed, including radiographs, periodontal probing with PerioWise (Premier Dental Products), and a thorough oral cancer screening exam, which included the use of visual screening technology VELscope [LED Dental]). Diagnostic model impressions were made using noncustom disposable trays (COE Spacer Trays [GC America]) and a high-quality vinyl polysiloxane (VPS) alginate substitute (Status Blue [DMG America]). Diagnostic casts were created and after an advance treatment plan consultation with my dental technician (Steven Killian, CDT), upper and lower wax-ups (Figures 5 and 6) were fabricated at the minimal vertical dimension of occlusion that would be needed to restore the patient with proper aesthetics and function.

Figure 5. Upper wax-up with additions to increase vertical dimension of occlusion (VDO).	Figure 6. Lower wax-up with additions to increase VDO.
Figure 7. Horizontal fracture of No. 9.	Figure 8. Extraction completed, socket grafted with 4Bone BCH bone graft (MIS Implants Technologies).
Figure 9. Reinforced temporary bridge cemented immediately over extraction site.	Figure 10. Upper occlusal markings immediately after rehabilitation was completed.
Figure 11. Lower occlusal markings immediately after rehabilitation was completed.	Figure 12. Metal crown with acrylic facing in window.

It turned out that the left central incisor (tooth No. 9) had to be removed due to a horizontal fracture about halfway up the root (Figure 7). While impossible to know for sure, I wondered if this fracture occurred as a result of many years of severe daytime bruxing, especially since the crossover motion was directly on No. 9. Using a Heidbrink Straight Elevator, Plain Edge, and Heidbrink Root Tip Picks, Plain Edge (both Brasseler USA), I removed No. 9 in 2 pieces. To maintain bone and soft-tissue shape, and 4Bone BCH bone graft (MIS Implants Technologies) (Figure 8) was placed in the socket and then covered with a collagen membrane (Helioplast [Integra Miltex]). A provisional bridge (Luxatemp [DMG America]) that was reinforced using embedded polyethylene fiber (Connect [Kerr]) was fabricated and cemented (GC TEMP ADVANTAGE [GC America]) (Figure 9). All crown preparations involved in this case were done using various shaped single-use diamond burs (Piranha [SS White Burs]).

While waiting for full healing of the No. 9 area, other phases of the rehabilitation were completed. Core buildups were placed (Clearfil S3 Plus adhesive with Clearfil DC Core Plus [Kuraray America]) as needed. After packing a braided gingival retraction cord (Ultrapak [Ultradent Products]), VPS impressions (Identium Medium and Light [Kettenbach USA]) for the planned crowns, veneers, and fixed bridges were taken.

The porcelain veneers (Halo [Shofu Dental]) on teeth Nos. 22 to 27 were made on refractory models and bonded in place (Adper Single Bond Plus and Rely-X Veneer Cement [both 3M ESPE]). Individual lithium disilicate crowns (IPS e.max [Ivoclar Vivadent]) were fabricated and then bonded in place using a resin cement (Panavia F 2.0 [Kuraray America]). The zirconia fixed bridge on the mandibular right (Sagemax NexxZr T [Sagemax Bioceramics] zirconia substructure with VITA VM9 [VITA North America] layering porcelain) was cemented (G-CEM LinkAce [GC America]). When the tissue in the No. 9 area was fully healed, a fixed bridge was made with the same materials as the lower right bridge (see above) and cemented with Clearfil Panavia SA cement (Kuraray America). Before cementing the bridges with zirconia substructures, to maximize adhesion, a universal cleaning paste (Ivoclean [Ivoclar Vivadent]) was applied for 20 seconds and then rinsed thoroughly to ensure a surface that would be free from any salivary phospholipids accumulated during try-in.

Upon completion of the entire rehabilitation (done prior to the porcelain fracture of tooth No. 9), a thorough occlusal evaluation was performed. Figures 10 and 11 show a satisfactory occlusal scheme that required minimal adjustment. Bilateral simultaneous contact of the posterior teeth was present. There were light contacts on the incisors with the canines bearing most of the contact anteriorly. A few minor adjustments were made using a No. 868-022 fine single-use diamond (Piranha) and the ceramic surfaces polished to a high luster (Jazz P3S polishers [SS White Burs]).

After the Rehabiltation and Second Porcelain Repair
After the second porcelain repair on No. 9, my technician and I decided to try designing the second bridge using an old idea with new materials. We needed more fracture resistance on the incisal edges, especially on No. 9. Zirconia was a likely choice for strength and, properly adjusted and fully polished, it would be kinder to the opposing porcelain veneers during any unprotected bruxing motions. Since monolithic zirconia, even the newer translucent versions (which are approximately half the strength of their more opaque versions), would not be the most aesthetic material in the aesthetic zone for this case, my technician suggested designing a zirconia frame that would cover the palatals completely and the incisal edges. He’d create windows where conventional aesthetic porcelain could be fused to the zirconia frame. The idea was reminiscent of gold frame bridges with windows cut out where acrylic would be processed (Figure 12). The design of the new frame can be seen in Figures 13 and 14.

Figure 13. Screen shot of the CAD for all-zirconia substructure with “windows” for properly supported layered porcelain.	Figure 14. CAD of all-zirconia palatal surfaces and incisal edges.
Figure 15. Try-in of Primopattern frame (Primotec).	Figure 16. The new Nos. 6 to 11 fixed partial denture (FPD) with milled (CAM) all-zirconia palatal surfaces and incisal edges.

Figure 17. Crossover position, showing contact on No. 9; approaching 2 years after new Nos. 6 to 11 FPD design.

Using a No. 18161 Great White Z diamond (SS White Burs), the re-repaired bridge was sectioned and removed. A new temporary bridge (Luxatemp) was cemented (GC TEMP ADVANTAGE). Final VPS impressions were taken (Impregum Penta Soft Medium and Light Body [3M ESPE]) along with a bite registration (O-Bite [DMG America]).
Before fabrication, a try-in was done with a frame made of Primopattern LC Paste and Gel (Primotec) (Figure 15). After confirming the fit of the frame, we knew the impression and scan were accurate.

The new bridge (Figure 16) was fabricated by our laboratory team using the following equipment and products:

• VITA VM9 porcelain for “windows” (VITA North America)
• Sagemax NexxZr T zirconia (Sagemax Bioceramics)
• Zirconzahn Prettau acid liquid colorant (Zirkonzahn USA)
• 3Shape D810 scanner/design system (DENTSPLY International)
• Roland DWX 50 for milling (Roland DGA Corp)
• Sum 3-D milling software (CIM system).

Delivery of the Fixed Prosthesis Featuring the Advanced Substructure Design
Insertion day arrived, and the new zirconia bridge with porcelain windows was tried in and evaluated for fit, appearance, and occlusion. All requirements were met. The abutment teeth were cleaned with a MicroEtcher IIA (Danville Materials) and the intaglio of the prosthesis was cleaned (Ivoclean). The bridge was cemented (Clearfil Panavia SA). The excess cement was light cured (Demetron 501 [Kerr]) (for only 5 seconds for easy cleanup) and removed. Seating pressure was maintained for 5 minutes while the cement inside the bridge set. (Note: When delivering zirconia restorations, remember that light will not adequately penetrate the zirconia to fully cure a light-activated resin cement.)

Figure 18. Pre-rehabilitation (July 2011): pre-op smile showing muscle strain and collapsed appearance.	Figure 19. Rehabilitation post-op with new porcelain-zirconia bridge. Note the more relaxed facial muscles and smile.

MAINTENANCE PHASE
Since this patient was observed to be extremely caries prone, he continues to be on a regimen that includes the use of MI Paste Plus (GC America), and the daily home use of his electric toothbrush (Sonicare [Philips Oral Healthcare]) with PreviDent 5000 Plus (Colgate) toothpaste. At his recall visits, our hygienist uses Ultradent Diamond Polish Mint (Ultradent Products) to polish and maintain his porcelain surfaces. In addition, in-office fluoride treatments are done with Kolorz Neutral Fluoride Foam (DMG America).

It is now approaching 2 years since the new (Nos. 6 to 11) PFZ bridge with the specially designed substructure has been in service. Fortunately, to date, there have been no chips or other fractures on any of the incisal edges, despite the continued severe crossover motion (Figure 17) that is simply a part of the patient’s daytime bruxing. Figures 18 and 19 demonstrate the changes in the patient’s face and smile. He no longer strains to smile and his facial muscles are in a much more relaxed position.

Acknowledgment
The author wishes to gratefully acknowledge and thank Steve Killian, CDT, and his skilled laboratory team at Killian Dental Ceramics in Irvine, Calif. Mr. Killian’s technical expertise, effort, and quest for answers helped Dr. Fier’s dental team find a solution to the perplexing problem of fractured porcelain. He can be reached at (800) 317-7100 or at cdt@killiandental.com.

References

1. Lobbezoo F, Ahlberg J, Glaros AG, et al. Bruxism defined and graded: an international consensus. J Oral Rehabil. 2013;40:2-4.
2. Shetty S, Pitti V, Satish Babu CL, et al. Bruxism: a literature review. J Indian Prosthodont Soc. 2010;10:141-148.
3. Kois JC. Functional occlusion II: complex restorative management [paper course materials]. koiscenter.com/store/coursemateriallist.aspx#koiscoursematerialspapermaterials. Accessed May 6, 2015.

Dr. Fier is a full-time practicing clinician, lectures internationally on aesthetic and restorative dentistry, and is the executive vice president of the American Society for Dental Aesthetics. He is a Fellow of the American Society for Dental Aesthetics and a Diplomate of the American Board of Aesthetic Dentistry, and he was honored with Fellowships in the American College of Dentists, the International College of Dentists, the Academy of Dental-Facial Esthetics, and the Academy of Dentistry International. He is a contributing editor for REALITY and is on the Dental Advisory Board of Dentistry Today. Since 1997, he has been listed in Dentistry Today’s annual Leaders in Continuing Education directory. He can be reached at (845) 354-4300 or via email at docmarv@optonline.net.

Disclosure: Dr. Fier has no financial interest in any of the companies mentioned in this article and received no compensation for writing this article.