January 5, 2017
by Lawrence Yanover, DDS, PhD, FRCD(C)
One of the greatest challenges in paediatric dentistry is aesthetic restoration of the primary maxillary dentition. We are faced with both a restorative and behaviour management challenge due to the lack of cooperation often exhibited by young children. These patients often present to the dentist between the ages of two and three with decay on the primary anterior teeth commonly diagnosed as nursing bottle decay. Treatment must be delivered in a timely fashion to preserve existing tooth structure, minimize discomfort as well as preserve function and aesthetics.
Although resin restorations are ideal for smaller lesions (Figs. 1, 2), long-term success diminishes with lesions involving more than three surfaces or sub-gingival caries, where a dry field can rarely be assured. 1 Preveneered stainless steel restorations can be recommended (Figs. 3, 4), but a silver lingual surface can often be observed and the aesthetic veneer can eventually show wear or failure (Fig. 5). 2 In the past few years, preformed anterior zirconia crowns have been introduced and display excellent aesthetics and long term durability, making them an ideal choice for full coverage repair of primary anterior teeth (Figs. 6, 7). 3
Moderate decay of primary anterior teeth.
Composite restoration of moderate decay on primary anterior teeth.
Radiograph of extensive caries on primary anterior teeth.
Restoration of extensive caries (Fig. 3) by using preveneered stainless steel crowns.
Loss of veneer on preveneered stainless steel crowns.
Caries on primary anterior teeth requiring aesthetic restoration.
Zirconia crowns (NuSmile) restoring caries on primary anterior teeth (Fig. 6).
A 3-year-old (male) presented with extensive decay of the four primary anterior teeth (Fig. 8). Visual and radiographic examination was conducted with limited cooperation. After reviewing dietary recommendations to the family to help prevent further decay to other tooth surfaces, behaviour and restorative options were reviewed. The family accepted general anaesthesia to provide a predictable solution to behaviour management and ensure optimal conditions for the demanding aesthetic procedures. Zirconia crowns (NuSmile, Houston, Texas, USA) were selected to provide optimal aesthetics and durability. Possible pulp therapy was discussed and would be used as needed after caries removal and tooth preparation.
Extensive decay in the primary anterior dentition.
The patient was placed under general anaesthesia by a certified anesthesiologist with intravenous and inhalation anaesthetic agents using nasal intubation. After throat pack placement and infiltration of local anaesthetic, a rubber dam was placed by clamping the second primary molar and isolating the anteriors, using a slit dam technique. A football fine finishing diamond was used to reduce the lingual surfaces of the four anterior teeth. This was followed by incisal, buccal, medial and distal reduction to the gingival margin using a flame fine finishing bur. The bur was then carefully placed one millimetre sub gingival for further reduction circumferentially (Fig. 9). At this point, pink Nu Smile try-in crowns were selected for each tooth to closely approximate the ideal mesial-distal width of the tooth. Further selective adjustments to the prepared tooth were initiated to produce ideal seating of the crown. Once the fit was confirmed, all the crowns were placed on the prepared teeth to confirm ideal alignment. The try-in crowns were then removed and retention grooves were placed on the buccal, mesial and distal of each tooth about 0.5 millimetres deep to enhance crown retention. All other teeth were restored at this time to allow for hemostasis around the primary anterior teeth. After all other restorations were completed, hemostasis was confirmed and the teeth were gently cleaned of contaminants and air dried. The appropriate matching final zirconia crowns were selected for cementation in a two-stage process, with the right central and lateral incisor placed first. Resin modified glass ionomer cement (Fuji plus, GC America, Alsip, Ill., USA) was mixed, placed into the two crowns, followed by cementation until fully seated and perfectly aligned in the arch. They were held firmly in place until the cement was set and then the extra cement was removed from the zirconia surface. This was followed by cementation of the left central and lateral incisor. Again these crowns were carefully held in place until the cement was set and the excess was then removed. The occlusion was then inspected for any interference. Floss was used to verify that the interproximal surfaces were free of cement. All surfaces were then polished with prophylaxis paste to ensure no residual cement was left on any surface (Fig. 10). The oral cavity was carefully cleaned prior to the removal of the throat pack and the waking of the patient. The patient was then placed in recovery, which was uneventful. The patient was seen at recall six months postoperatively and documentation of the restorative treatment was obtained.
Preparation of primary anterior teeth for zirconia crowns.
Completed restorative treatment (Fig. 8), including zirconia crowns on the primary anterior teeth.
The selection of zirconia crowns for full coverage restoration of the primary teeth produced a stable and aesthetic result. The soft tissue response in this case was excellent. The use of a general anaesthesia led to ideal conditions for careful tooth preparation and crown placement. Teeth with less carious destruction could ideally be restored with composite resin materials, often utilizing the strip crown technique. If significant sub gingival decay were present, veneered stainless steel crowns might be selected, as they can be placed more subgingivally for better retention and are also more tolerant of tissue haemorrhage that may not be controlled with a hemostatic agent. Current manufacturers of zirconia crowns in North America include NuSmile (NuSmile, Houston, Texas, USA), EZ-Pedo (EZ-Pedo, Loomis, Calif., USA), Cheng Crowns (Cheng Crowns, Exton, Pa, USA) and Kinder Krowns (Kinder Krowns, St Louis Park Minn., USA). Each manufacturer has unique and proprietary features, recommendations for tooth preparation as well as cementation protocols. Cement recommendations vary from resin cement, resin modified glass ionomers or pure glass ionomers. Two new bioactive cements have also been introduced, including Ceramir Crown and Bridge (Doxa Dental, Chicago, Ill., USA) and BioCem (NuSmile). Long-term clinical trials are not yet available to determine the ideal cement and crown combination, so it is suggested that manufacturer recommendations be followed.
Preformed zirconia crowns used for the aesthetic restoration of the paediatric anterior dentition have led to the successful treatment of a challenging restorative dilemma. They provide a stable, durable and aesthetic result. Long-term studies are required to determine ideal crown design and cementation protocols. The introduction of these materials has led to a new era in the management of extensive dental decay in children. OH
Disclaimer: This author has no financial interest in the products discussed in this paper.
Oral Health welcomes this original article.
1. Ram D, Fuks AB. Clinical performance of resin-bonded composite strip crowns in primary incisors:a retrospective study. Int J Paediatric Dent 2006;16(1):49-54.
2. MacLean JK, Champagne CE, Waggoner WF, Ditmyer MM, Cassamissimo P. Clinical outcomes for primary anterior teeth treated with pre veneered stainless steel crowns. Pediatr Dent 2007;29:377-81.
3. Holsinger DM, Wells MH, Scarbecz M, Donaldson M. Clinical evaluation and parental satisfaction with paediatric zirconia anterior crowns. Pediatr Dent 2016;38:192-97.
About the Author
Dr. Lawrence Yanover is a board certified Pediatric dentist with a full-time practice in St. Catharines, ON. He maintains privileges in hospitals within the Golden Horseshoe and Nunavut where he cares for patients under general anaesthesia. He is also a clinical instructor at The University of Toronto Faculty of Dentistry.