REVIEW ARTICLE REVOLUTION IN PEDIATRIC RESTORATIVE DENTISTRY- ZIRCONIA CROWNS

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1 REVIEW ARTICLE REVOLUTION IN PEDIATRIC RESTORATIVE DENTISTRY- ZIRCONIA CROWNS Meenu Bhola 1, Geetika Jindal 2 1 Professor and Head, 2 Senior Lecturer, Department of Pedodontics and Preventive Dentistry, Dasmesh Institute of Research and Dental Sciences, Faridkot (Punjab) ABSTRACT: Maintenance of the primary dentition in a non pathologic and healthy condition is important for the overall well being of the child. Treatment of the severely destructed teeth poses a challenge for the pediatric dentist as three important considerations have to be kept in mind; patient s behavioral management, preservation of the tooth structure and parental satisfaction. Effort has been made to bring together the various approaches for full coverage restorations in pediatric dental practice. Today s market is full with variety of esthetic crowns. Each of them is present with different clinical consideration, advantages and disadvantages. Crowns are indicated in case of mutilated teeth due to any reason. Many options exist to repair carious teeth in pediatric patients like from stainless steel crowns to other esthetic crowns like strip crowns and zirconium crowns which are in increased demand in these days. Keywords: Caries, Esthetics, Crowns, Zirconia, Restorations Correspondence: Dr. Geetika Jindal, Senior Lecturer, Department of Periodontology Pedodontics and Preventive Dentistry, Talwandi road, Faridkot (Punjab) , geetikajindal60@gmail.com How to cite the article: Bhola M, Jindal G. Revolution in pediatric restorative dentistry- zirconia crowns. J Stomatognathic Sci 2016;6(1): I ntroduction Dental decay in children s teeth is a significant public health problem, affecting 60% to 90% of school children in industrialized countries. 4 Carious destruction of tooth structure in a child leads to various abnormalities which affect esthetics, self-esteem, mastication, speech, maintenance of arch length and development of oral habits which in general causes disturbance of overall health. Hence, the mutilated teeth need to be restored to preserve the integrity of dentition till the eruption of permanent teeth. Several options are available for providing full coverage restoration for the primary dentition, with each approach having advantages and disadvantages. 7 Commonly used full coverage crowns include stainless steel crowns and its modifications, polycarbonate crowns and strip crowns. The search for the ideal full coverage restorations in pediatric dentistry continues. This review throws light on zirconia crowns along with their clinical implications. ZIRCONIA PAEDIATRIC CROWNS 5 Zirconia is polycrystalline ceramic without glass component. It is polymorph that occurs in three from: - Pure zirconia stable at C aclonic Above C At C The volume expansion caused by different forms of zirconia induces large stress which leads Zirconia to crack. By adding small amount of yttria these phase changes are eliminated and the resulting material has high compressive strength, high fracture resistance, corrosion resistance, durability and biocompatibility. Zirconia (zirconium dioxide) crowns are made of solid monolithic zirconia ceramic material. These are metal free crowns. Although discovered in 1789 by the German chemist Martin Heinrich Klaproth, zirconia has been used as a biomaterial since the late 1960s. Its use as a dental restorative material became popular in the early 2000s with the advent of CAD-CAM technology. In the later part of the decade they became available as preformed crowns for primary teeth. Some of the commercially available pediatric zirconia crowns are discussed: 1. E Z Pedo crowns 2. NuSmile Zirconia crowns 3. Kinder Zirconia pediatric crowns Nusmile Zr: It is made up of high grade monolith Zr ceramic. It has increased durability with strength more than enamel. Translucency of Zr ceramic provides excellent esthetics and prevents the problem of dark tooth show through pulpally treated teeth. It is also provided with Nusmile try-in crown to check fitting prior to final cementation. This feature saves clinician s chair side time. 22

2 Figure 1- Nu smile zirconia crowns Kinder crowns Zr: It is based on nano technology, produces most consistent, high quality zirconia. It has polished surface to reduce opposite enamel wear. It has internal retention system which locks the restoration after cementation. These retention bands also provide an additional surface for bonding. Fine fethered margin of zirconia kinder crown makes the emergence profile for the crown as natural as possible. It is available in two sizes: mid size and regular size. Figure 3- EZ Zirconia Crowns Figure 2-Kinder crowns EZ Pedo Crowns: It comes with the patented retention technology, zir lock ultra i.e. retentive grooves which extent all the way to the crown margins, preventing cement washout. It also prevents entry of harmful bacteria, moreover it provides two times more surface area for bonding. Additional retention is provided through blasting with aluminium oxide. TOOTH PREPARATION 8 Select the correct crown size by placing the incisal edge of the crown against the incisal edge of the tooth. (Fig 4) Reduce the incisal edge 1.5-2mm (Fig 5) Reduce the labial surface a minimum of of tooth structure in three planes (gingival-middle-incisal thirds). These three planes extend from 1-2mm subgingivally all the way to the middle of the incisal edge of the preparation (Fig 6). Reduce the lingual surface by removing mm of tooth structure from the lingual surface, extending from 1-2mm subgingivally to the middle of the incisal edge of the preparation following the natural contours of the existing clinical crown. The facial and lingual preparation should meet in a thin incisal edge. Check the occlusion to ensure there is adequate clearance from opposing dentition. (Fig 7)The red arrows mark the most common areas of internal interference that, if under-prepared, will make it difficult to seat zirconia crowns. Lingual and facial reductions should meet at a thin incisal edge of the final restoration. This thin incisal edge helps to reduce internal interferences between the tooth and the internal surface of the crown (Fig 8). The circumference of the overall preparation should be ovoid when viewed from the incisal edge. Facial and lingual surfaces should not be prepared flat, but rather curved interproximally. Removing extra material in these areas will ensure an easier fit with less internal interference and allow mesial /distal rotation for a better alignment of the crown during final cementation. (Fig 9) CERAMIC CROWN ADJUSTMENT It is possible to adjust a pedo ceramic crown. However because it is ceramic and cannot be trimmed with scissors like a traditional stainless steel crown, it is necessary to use 23

3 a high speed, fine diamond with lots of waters because excessive heat could cause fractures in the crown s ceramic structure. Occlusal and interproximal adjustments are not recommended, as these will remove the crown s glaze and possibly create a weak area of thin ceramic. (Fig 10) PASSIVE FIT It is very important that zirconia pedo crowns fit passively because they do not flex and pushing harder will not work. Do not attempt to force a crown to fit. Excessive pressure may fracture the crown. The appropriate size crown should fit passively and completely subgingivally without distorting the gingival tissue. EZ- Pedo Crowns have internal ZirLock grooves that increase the overall surface area of the restoration, providing more retention and improving overall clinical success. (Fig 11) Figure 6- Labial surface reduction Figure 4- Selection of crown size Figure 7- Lingual surface reduction PREPARATION FOR CEMENTATION Rinse the preparation and remove all blood and residue from the tooth. If bleeding continues, squeeze the preparation with a moist 2x2 gauze or carefully apply Superoxol to the tissue using a micro brush. Using peroxide or alcohol, thoroughly clean the internal surface of the crown so that all blood residue is removed. (Fig 12) Figure 5- Incisal edge reduction CEMENTATION Cementation is the most important step to create a beautiful smile. Central incisors should always be cemented together first and then the lateral incisors. Apply consistent, firm finger pressure during cementation using self adhesive resin. The crown should remain undisturbed until the cement has completely hardened. Wiping excess cement from the facial embrasure will allow a clearer facial view 24

4 and ensure a better final alignment, dramatically improving the final esthetic result. Tooth labeling can be scratched off with a spoon or polished off with coarse prophylaxis paste. (Fig 13) With all full coverage restorations parents must be advised to institute appropriate preventive health practices (elimination of sugar containing drinks, regular tooth brushing and topical fluoride application) to maximize gingival health and minimize the recurrence of caries under the restorations. Figure 10- Ceramic crown adjustment Figure 8- Ideal preparation Figure 11- Passive fit of crown Figure 9- Complete tooth preparation Figure 12- Preparation of cementation 25

5 primary dentition. Current research on passive fit prefabricated zirconia crowns for primary anterior teeth is limited. Current wide ranges of available esthetic crowns help us to meet the parental satisfaction and acceptance in terms of esthetics. Figure 13- Cementation of crown ADVANTAGES 4 They are very aesthetic, with greater durability than composite strip crowns and pre-veneered crowns. They are not as technique sensitive as composite strip crowns as the fabricated crown is cemented with self-adhesive resin cement rather than bonding. DISADVANTAGES 4 They are not recommended in bruxism. Greater tooth reduction is required and they have high cost. The extra strength of zirconia crowns has an abrasive effect on the opposing tooth. This may negatively impact the tooth root. CONCLUSION Esthetics has become a respectable concept in dentistry today. So, impact of esthetics should always be considered in treatment plan as it has vital role in child s overall general health and psychological well being. Zirconia is currently the strongest dental ceramic available and is also esthetically pleasing. Even though zirconia is widely accepted as a restorative material for the permanent dentition, it is a relatively new restorative material for the REFERENCES 1. American Academy Of Pediatric Dentistry, Guideline On Restorative Dentistry,, Reference Manual V 37 / NO 6 15 / Attari N, Robert JF. Restoration of primary teeth with crowns-a systemic review of the literature. Eur Arch Pediatr Dent Jan;7(2): Croll TP, Helpin ML. Preformed resin-veneered stainless steel crowns for restoration of primary incisors. Quintessence Int 1996;27: Garg V, Panda Anup, Crowns In Pediatric Dentistry: A Review, Journal Of Advanced Medical And Dental Sciences Research Vol. 4 Issue 2 March - April Jyoti V Tote, Alkesh Godhane, Posterior Esthetic Crowns In Pediatric Dentistry, Int J Dent Med Res MAR- APR 2015 VOL 1 ISSUE 6 6. Kashinatha H.M, Tooth Preparation And Cementation Guidelines For Zirconia Based Restorations - A Scientific Perspective, Journal Of Dentistry And Oral Biosciences 2011/Volume2/ Issue2 7. Ram D, Fuks A: Clinical performance of resin bonded composite strip crowns in primary incisors: a retrospective study. International Journal of Paediatric Dentistry 2006, 16: Schwartz Steven, Full Coverage Aesthetic Restoration Of Anterior Primary Teeth, Continuing Education Course, Revised March 26, Sajjanshetty S, Patil P, Hugar D, Rajkumar K: Pediatric Preformed Metal Crowns-An Update.Journal of Dental and Allied Sciences 2013, 2: Usha M, Deepak V, Venkat S, Gargi M. Treatment of severely mutilated incisors: a challenge to the pedodontist.j Indian Soc Pedo Prev Dent 2007;25 Suppl:S34-6. Source of support: Nil Conflict of interest: None declared 26