Laser-Assisted Aesthetic Osseous Crown Lengthening During the Crown Preparation Appointment

Introduction
Once you have been in private practice long enough, you can pretty much expect the unexpected. We become very good at not allowing planning and scheduling mistakes to disrupt our office or inconvenience the patient. In cases of complicated cosmetic rehabilitation, the schedule often depends on patient factors, such as insurance, finances, work schedule, distance from the office and travel time. For the treatment of gummy smiles and uneven gingival contours in the anterior dentition, ideal smile design requires that rehabilitation be accomplished in several steps, with a lengthy healing period in between these steps. Proper diagnosis and correct selection of soft tissue crown lengthening vs. osseous crown lengthening is the key to the long-term success of our restorations and maintaining good periodontal health.

This article will showcase the five-year success of osseous crown lengthening surgery performed with the Waterlase MD Er,Cr:YSGG 2780nm laser, at the time of crown preparation and try to explain reasons why such success was possible using hard tissue laser technology.

Case Report
A healthy 55-year-old female patient with severe generalized attrition, as indicated by the panoramic X-ray (Fig. 1) has been undergoing a full mouth rehabilitation, over the previous five-years. Her initial chief complaint was frequently breaking her anterior composite restorations. Vertical dimension of occlusion has been re-established first using composite build ups and verified for a period of 6 months of normal masticatory and speech functions. Coincidentally, frequency of migraine-type headaches has also been reduced as reported by the patient. During the subsequent 4 years, the posterior build-ups have been converted to full coverage Lava Zirconia crowns, leaving only the anterior teeth to be completed. In 2010, the patient retired and moved to Deep River, a town 2 hours drive from Ottawa, and had not been to our office for a year. In November 2011 she has made an appointment to start the crowns on the last remaining 6 anterior teeth, 13-23. The pre-operative photo (Fig. 2) clearly indicated a disharmony in gingival contours and a slight gummy smile. Upon quick periodontal examination and bone sounding, a Type 2 aesthetic crown lengthening surgery1 was indicated. Without performing the surgery first, we would either have to fabricate crowns of various heights, which goes against the whole idea of elective cosmetic dentistry, or another option would be to create the crowns with ideal proportions, but thus impinge on biological width (BW) of teeth 11, 22 and 23.

The impingement on BW would result in gingival tissue re-establishing its original dimension through bone resorption or chronic inflammation. 1 The anatomy of dentogingival junction and the concept of biological width has been known since the 1960’s. 2 It is made up of sulcus depth 0.69mm, epithelial attachment 0.97mm and connective tissue 1.07mm for a total BW of 2.73mm, or around 3mm from the crestal bone to the gingival margin (Fig. 3). 3 A number of studies looked at the healing process following osseous periodontal surgery and showed an average loss of alveolar crest of 0.5-0.8mm at 6 months following the procedure. 4 Some studies found no significant change in free gingival margin from three to six months, 5 while others showed a 12-month healing period was required. 6 Raising a mucoperiosteal flap, as a general rule, increased both healing time and resorption of alveolar process.

With the patient in the chair expecting definitive work to be started on the final phase of her cosmetic transformation, we were faced with the dilemma: do we perform crown lengthening surgery today and reschedule crown preparation by the recommended 3-6 months healing period, or do we leave unaesthetic gingival contours and make the crowns uneven? Neither one of these options was palatable to myself or the patient. Luckily we had at our disposal the Waterlase MD, hard tissue laser, that has been shown to be effective in the flapless osseous crown lengthening approach, which allows predictable and fast healing. 7 Effective hemostasis, minimal healing delay and complete healing of bone defects, within 56 days, has been shown in animal studies. 8 Er,Cr:YSGG 2780nm laser wavelength allows for precise surgical removal of alveolar process of bone and surrounding gingival tissue with minimal thermal damage. 9 The ability to clearly see how this laser gently removes soft tissue microns at a time without blood constantly seeping into the surgeon’s field of view is what makes such surgery possible and even fun for the general dentist. Using the laser tip as a chisel, we are able to sculpt the gingival and bony architecture to create a great foundation for our cosmetic restorations. The lack of thermal side effects on the hard tissues is what makes this surgery so painless for the patient and enables us to forego the three months healing period, and proceed with the fabrication of the final crown restorations much sooner.10 It is for this reason, we were able to offer our patient an option of performing Type 2 osseous crown lengthening prior to crown preparation, in the same appointment, and still be able to make the final impression and place definitive restorations, two to three weeks later.

Fig. 1
Panoramic X-ray prior to VDO correction.

Fig. 2
Pre-op photo at crown preparation appointment.

Fig. 3
Physiologic dimensions of periodontium significant to restorative dentist. From Maynard JG et al [3].

Procedure
After administering sufficient local anesthesia, to last the entire 3-hour appointment, the Waterlase MD, with Gold HP and MZ5 14mm long tip, was used to establish ideal gingival contours (Fig. 4). Gingiva on the buccal aspect of teeth 11, 22 and 23 was modified using the soft tissue cutting settings (2.5W, 30Hz, H-mode, 20%W/20%A). A permanent black marker was used to indicate 3 mm depth on the disposable fiber tip, which allowed precise removal of crestal bone to create the desired biological width. Alveolar bone reduction was performed, using the bone cutting settings (3.0W, 30Hz, H-mode, 60%W/40%A), until the black mark coincided with the newly established gingival contour (Fig. 5). The surgical procedure took approximately 30-40 minutes from the start of the appointment.

The next step was crown preparation, which was completed using a conventional high speed handpiece (Fig. 6). By the time crown preparation was completed, 1.5 hours later, the bleeding from osseous bone reduction had stopped and the impression could be taken. Instead of packing a retraction cord, laser troughing for impression was accomplished with the aid of Waterlase MD, using same MZ5 14mm long tip, but at the troughing setting (1.25W, 50Hz, S-mode, 10%W/10%A). The buccal gingiva of teeth 11, 22 and 23 did not require any further retraction following osseous crown lengthening. The remaining buccal contours of teeth 13, 12, 2,1 and all the lingual contours, were prepared using laser troughing setting. With this technique we were able to take the final impression easily with good moisture and bleeding control, since the newly re-contoured tissues did not have to be disturbed.

Fig. 4
Gingival recontouring.

Fig. 5
Osseous reduction to create biological width.

Fig. 6
Crown preparation and troughing for impression.

The remaining time was spent on temporization, which due to lack of lead time and preparation had to be done chair-side, using Luxa-temp Bisacryl Automix temporary acrylic material, by DMG America. The temporary bridge consisted of six splinted crowns due to time constraints. The patient was scheduled to return in two weeks to receive her final Lava Zirconia crown restorations. A1 Vita shade guide color was chosen to blend well with the posterior crowns, fabricated previously.

At the final insertion appointment, the temporary acrylic bridge was removed and the gingival tissues appeared healthy. There was no bleeding and normal probing depths of 1-2mm, were measured. The interdental papillae appeared slightly blunted, as a result of having splinted temporary restoration for the past two weeks and the patient’s inability to access interdental spaces with proper oral hygiene. The six crowns were individually cemented using Rely-X luting resin modified glass ionomer cement by 3M. The patient was thrilled with the result (Fig. 7a, 7b), more so after she was reassured that the blunted papilla was a temporary effect that would correct itself after resuming regular brushing and flossing, over the next few weeks. Upon our next examination of the patient, one year later, the papilla did indeed completely fill in the interdental spaces and the gingival contours were healthy and stable at the level established during the osseous crown lengthening surgery. Five years later, the patient remains extremely happy with her decision to have this cosmetic rehabilitation done. The crown restorations and gingival contours of anterior teeth remain stable and healthy (Fig. 8a, 8b).

Fig. 7a
Photo at cementation appointment.

Fig. 7b
Photo at cementation appointment.

Fig. 8a
Photo 1 year post-op.

Fig. 8b
Photo 1 year post-op.

Fig. 9a
Photo 5 years post-op.

Fig. 9b
Photo 5 years post-op.

Discussion
In complicated aesthetic cases, such as this one, a successful outcome depends upon a number of factors: patient’s compliance with the prescribed regimen of home care and proper planning and scheduling of all phases of treatment; training and skill of the dentist; respecting periodontal health; and the very important concept of biological width. Once a proper diagnosis is made, there are many treatment modalities that can be used to accomplish the change in gingival margin and osseous position. Laser technology can offer advantages which are not available with conventional methods, namely better visibility due to bleeding control, faster healing and less post-operative discomfort, due to the micro-invasive technique and reduced inflammation. 11 A thorough understanding of laser-tissue interactions and mechanisms of action is crucial in achieving good outcomes. For example, studies comparing wound healing from a scalpel vs. Er,Cr:YSGG laser vs. diode laser incisions observed more acute inflammation and tissue damage in diode laser group, as compared to the Er,Cr:YSGG or scalpel. Diode lasers, although very common in a lot of dental offices due to their affordability, have more thermal side effects. Caution must be exercised when diode lasers are used in close proximity to the hard tissues, such as teeth and bone. In fact, diode lasers should be restricted to soft tissue procedures only. However higher healing potential and cell proliferation was found in both diode and Er,Cr:YSGG lasers, as compared to scalpel incision. 12 Another study compared scalpel vs. Er,Cr;YSGG laser vs. CO2 laser and found more ulcerations, higher level of inflammatory mediators and slower healing at two weeks in the CO2 group. Although, CO2 laser has better hemostatic ability, it resulted in greater tissue damage and inflammation than Er,Cr;YSGG laser or scalpel. Waterlase technology is advantageous in surgery due to low inflammatory response and minimal tissue damage. 13 Er:YAG 2940nm laser, a close relative of Waterlase wavelength, has been shown to produce more pronounced revascularization, fibroblast proliferation and less inflammatory infiltrate than CO2 laser and mechanical burr9, 14 and less callus formation than saw osteotomy. 15 It is quite clear that the decision regarding which laser wavelength to use in cosmetic applications, is of crucial importance. Training to use the laser properly and experience in observing the desired laser-tissue interactions is essential to treatment success and patient satisfaction.

Conclusion
Cosmetic rehabilitation cases require from the dental practitioner a high level of skill and continuing education, and from the patient, a high degree of compliance. Laser technology can help bridge the gap between the patient’s desire to have work done quickly and with fewer visits, shorter healing times and less discomfort, and the dentist’s need to follow sound biological principles and accepted techniques to achieve the best possible, predictable and long lasting cosmetic restorations. OH

Oral Health welcomes this original article.

References
1. Lee EA. Aesthetic crown lengthening: classification, biologic rationale, and treatment planning considerations. Pract Proced Aesthet Dent 2004;16(10):769-78
2. Garguilo AW, Wentz FM, Orban B. Dimensions and relations of the dentogingival junction in humans. J Periodontol. 1961; 32:261-67
3. Maynard JG, Wilson RD. Physiologic dimensions of the periodontium significant to the restorative dentist. J Periodontol. 1979;50(4):170-74
4. Wilderman MN, Pennel BM., King K, Barron JM. Histogenesis of repair following osseous surgery. J. Periodontol, 1970; 41(10): 551-65
5. Lanning SK, Waldrop TC, Gunsolley JC, Maynard JG. Surgical crown lengthening: evaluation of the biological width. J Periodontol 2003; 74(4): 468-74
6. Pontoriero R, Carnevale G. Surgical crown lengthening: a 12-month clinical would healing study. J Periodontol 2001;72(7): 841-48
7. Lowe R. Clinical use of the Er,Cr:YSGG laser for osseous crown lengthening: redefining the standard of care. Pract Proced Aesthet Dent 2006;18(4): S2-S9
8. Wang X, Zhang C, Matsumoto K. In vivo study of the healing processes that occur in the jaws of rabbits following perforation by an Er,Cr:YSGG laser. Lasers Med Sci 2005; 20:21-27
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13. Ryu SW, Lee SH, Yoon HJ. A comparative histological and immunohistochemical study of wound healing following incision with a scalpel, CO2 laser or Er,Cr:YSGG laser in the guinea pig oral mucosa. J Acta Odontol Scandinav 2012;70(6): 448-54
14. Sasaki KM, Aoki A, Ichinose S, Yoshino T, Yamada S, Ishikawa I. SEM and Fourier transformed infrared spectroscopy analysis of bone removal using Er:YAG and CO2 lasers. J Periodontol 2002;73(6): 1-10
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About the Author
Dr. Marina Polonsky DDS, MSc is a gold medal University of Toronto ’99 graduate, she maintains private general practice in Ottawa, Ontario with focus on multi-disciplinary treatment utilizing lasers of different wavelengths. She holds a Mastership from World Clinical Laser Institute (WCLI), Advanced Proficiency Certification from Academy of Laser Dentistry (ALD) and Master of Science in Lasers in Dentistry from RWTH University in Aachen, Germany.

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