Published on February 15, 2014
The Effect Of retentive groove,sandblasting & cement type on retentive strength of Stainless Steel crowns in primary second molars – An invitro comparative study - Veerabadhran et al J Indian Soc Pedod Prev Dent 2012;30:19-26
INDEX WHAT ARE STAINLESS STEEL CROWNS? INDICATIONS SS CROWNS Vs. MULTISURFACE RESTORATION FABRICATION OF SS CROWN SS CROWN MODIFICATION AIMS & OBJECTIVES OF THE STUDY MATERIALS & METHODS RESULTS DISCUSSION HIGHLIGHTS OF THE STUDY CONCLUSIONS
Stainless steel (preformed) crowns are prefabricated crown forms which can be adapted to individual primary molars and cemented in place to provide a definitive restoration American Academy of Pediatric Dentistry; Guideline on Pediatric Reestorative Dentistry 2012;35:226-234
CLASSIFICATION • BASED ON COMPOSITION 1. 2. 3. 4. STAINLESSS STEEL CROWN (UNITEK & ROCKY MOUNTAIN CROWNS) NICKEL BASE CROWNS (ION Ni-chro FROM 3M) TIN BASED CROWNS (Iso-form type) ALUMINIUM BASE CROWNS (Gold anodised )
COMPOSITION 18-8 CROWNS AUSTENITIC TYPE • Chromium- 17-19% • Nickel – 10-13% • Iron-67% • Minor elements-4% NICKEL BASE CROWNS • Nickel-72% • Chromium-14% • Iron-6-10% • Carbon-0.04% • Manganese-0.35% • Silicon-0.2%
• BASED ON MORPHOLOGY 1. UNCONTOURED/ UNTRIMMED CROWNS (ROCKY MOUNTAIN) 2. PRETRIMMED CROWNS (UNITEK STAINLESS STEEL CROWNS,3M,DE NOVO CROWNS) 3. PRECONTOURED CROWNS (Ni-chro ion crowns & Unitek 3M)
PREVEENERED CROWNS • Resin based composite bonded to occlusal & buccal surfaces • Allows minimal crimping • Aesthetic
Availability Crown Shape Number of sizes available Width range mm Upper 1st primary molars 6 7.2 to 9.2 Upper 2nd primary molars 6 9.2 to 11.2 Lower 1st primary molars 6 7.3 to 9.3 Lower 2nd primary molars 6 9.4 to 11.4 • Sizes 4 & 5 most often used • Supplied in kit form with user needing to reorder only those sizes frequently used
3MTM ESPETM UNITEKTM Stainless steel crowns CROWN SHAPE NUMBER OF SIZES AVAILABLE WIDTH RANGE mm Central/Lateral 12 4.2 to 8.0 Upper Cuspids 6 6.2 to 8.2 Lower Cuspids 6 4.8 to 6.8 Upper 1st primary molar 7 6.6 to 9.0 Upper 2nd primary molar 7 8.5 to 11.0 Lower 1st primary molar 6.9 to 9.3 7 Lower 2nd primary molar 7 8.5 to 11.5
INDICATIONS • Carious primary molars where more than two surfaces are affected/where one or two surface carious lesions are extensive. • Following pulpotomy or pulpectomy procedures • Primary molars affected by localized or generalized developmental problems • Fractured primary molars • Patients with high caries succeptibility Ray Stewart, Thomas Barber, Kenneth Troutman, Stephen Wei.Pediatric Dentistry- Scientific Foundations & Clinical Practice St Louis : Mosby;1982
• As an abutment for certain appliances, such as space maintainers. • In patients where routine oral hygiene measures are impaired. • In patients undergoing restorative care under general anaesthesia if two or more surfaces are involved. • In patients with infra-occluded primary molars to maintain mesiodistal space. Ray Stewart, Thomas Barber, Kenneth Troutman, Stephen Wei.Pediatric Dentistry- Scientific Foundations & Clinical Practice St Louis : Mosby;1982
SSCROWNS Vs MULTISURFACE RESTORATIONS • stainless steel crowns have markedly superior longevity when compared with multi-surface amalgam restorations • stainless steel crowns out-perform glass ionomer cements and composite restorations as well
ARMAMANTARIUM • CROWN CUTTING BURS- pear shaped, tapered fissured,finishing burs • PLIERS – Hoe pliers(#110),Johnson’s contouring plier#114,Ball & socket plier#112,Crimping pliers#417,Gordon plier #137,crown scissors • Scaler or any sharp instrument • Stone & Finishing burs for crown finishing • For cementation- luting cement,spatula,glass slab • Miscellaneous
FABRICATION OF STAINLESS STEEL CROWNS • PREOERATIVE STEPS : 1.Occlusal evaluation 2.Crown Selection • OPERATIVE STEPS
OCCLUSAL EVALUATION • • • • • • DIAGNOSTIC CAST MIDLINE CUSP-FOSSA RELATION CANINE RELATION EXTRUSION OF OPPOSING TOOTH MESIAL DRIFTING
CROWN SELECTION • MESIO DISTAL DIAMETER • LIGHT RESISTANCE TO SEATING • PROPER OCCLUSAL HEIGHT
CROWN SELECTION • Before Preparation : Vernier Caliper • After preparation : trial & error • Smallest crown selected (No.4 & No.5 commonly) • Friction to be felt when crown slips gingivally
• Crown should have : 1. Tight snap fit 2.Restore original contour & occlusal anatomy 3. Choose smallest crown that fits well
• THREE MAIN CONSIDERATIONS A) Adequate M-D width B) Crown: larger : tooth to be adapted C) Too large crown will rotate on the tooth
TOOTH PREPARATION INITIAL ADAPTATION OF CROWN SEATING OF CROWN CROWN CONTOURING CROWN CRIMPING FINAL ADAPTATION OF THE CROWN FINISHING , POLISHING & CEMENTATION OF CROWN
TOOTH PREPARATION • AIM To provide sufficient space for SSC To remove carious tooth structure To have sufficient tooth structure for retention
TOOTH PREPARATION Isolation Removal of Decay Crown Reduction : Occlusal Reduction Proximal Slicing Buccolingual Reduction Round Off all the Line angles
OCCLUSAL REDUCTION Humphery 1950 • All sides reduced • Retain crown structure Rapp 1966 • Occlusal reduction to keep atleast 4mm from gingival margin Mink & Bennett 1968 • Uniform occlusal reduction 11.5mm • Troutman & Kennedy support it
• Occlusal reduction
• Occlusal anatomy preservation
PROXIMAL REDUCTION • Wooden wedge interproximally • 69L/169L bur moved buccolingually • Begin at the marginal ridge & at 10◦ converging towards occclusal surface • Feather edge finish line • Pass explorer through proximal areas for evaluation
• Proximal reduction
ANGULATION OF SLICES PROPER SLICE IMPROPER SLICE
No ledge should form just a feather edge finish line •Rounding up of line angles
Proximal reduction Proximal box must be extended below the gingival crest to avoid leaving a ledge Ledge may cause : Obstructed crown placement Propping out of crown Stress area
BUCCAAL & LINGUAL REDUCTION • Natural Undercuts : retention • Mathewson 1974 Andlow & Rock 1984 Mink & Bennet 1968 – Large buccal bulge : buccal reduction required • Pinkham : Large mesiobuccal bulge ,both buccal & lingual reduction required
EVALUATION OF TOOTH PREPARATION • Explorer can be placed between the prepared tooth & proximal tooth • Occlusal clearance 1-2mm • Buccal & lingual surface converge slightly towards the occlusal if required then only reduced 0.5mm with feather edge margin
CROWN ADAPTATION(INITIAL) • • • • Try crown on the tooth : Lingual to buccal Mark scratch line Cut 1mm below it with scissors Place the crown again: If blanching seen : rescribe & retrim If doesn’t seat completely: reduce occlusal surface
GINGIVAL CONTOURS OF CROWN
CROWN CONTOURING • • • • Contouring pliers : Ball & socket plier # 112 Gordan plier #137 Johnson plier #114
• Contouring: the middle 1/3rd of the crown (Belling effect)
CROWN CRIMPING • Crimping:the gingival 1/3rd of the crown margin
• Seating of the crown: lingual to buccal “click” sound for a snap fit
• Evaluation : • Check with explorer : If margins open : recrimp If overextended : start again Blanching : Johnson 1987 Bitewing radiograph : More & Pink 1973
FINISHING & POLISHING
SS CROWN MODIFICATIONS • • • • • Undersized tooth / Oversized crown Oversized tooth / Undersized crown Deep subgingival caries Open faced SS Crowns Open Contact
UNDERSIZED TOOTH/ OVERSIZED CROWN(Mink & Hill 1971) Occur due to long standing nature of caries V-cut made on the buccal surface from gingival to occlusal surface Cut edges reapproximate d to overlap one another Crown tried on tooth & amount of overlap marked Overlaped edges spot welded
OVERSIZED TOOTH & UNDERSIZED CROWN Try the crown on the tooth Cut V on buccal or lingual side as needed Again try the crown on tooth Place ortho band and spot weld it
DEEP SUBGINGIVAL CARIES Routine crown preparation • Amalgam/GIC restoration substitute the tooth structure Band • Solder an extension on interproximal area of crown
OPEN CONTACT • Leads to food packing,plaque retention & gingivitis • Large crown selected • Interproximal contour exagerated with #112 plier • Or addition of solder inter proximally
OPEN FACED SS CROWNS Cut window in the crown which is • Just short of incisal edge • Gingivally till the height of gingival crest • Mesiodistally till line angles
OPEN FACED SS CROWN • • • • • • Composite Material on labial fenestration Time consuming Metal margins still visible Difficult to control hemorrhage Increased chair side time Gradual deterioration in appearance
AIMS & OBJECTIVES • Effect of retentive Groove placement on retention of SS Crown • Influence of cement type on Retentive strength • Efficacy of sandblasting of the crown on Crown retention • Retention of SSC on Maxillary primary 2nd Molar Vs that on Mandibular Primary 2nd Molar • Interation of any two factors mentioned above
MATERIALS & METHODS • Developing the experimental design matrix • Conducting the experiment as per design matrix • Recording the Results i.e Retentive Strength
THE DESIGN MATRIX
THE EXPERIMENT • Specimen: Total 16 extracted intact human primary maxillary and mandibular second molars(8 each) were mounted in Autopolymerising Resin • Pretrimmed Precontoured SS Crowns were selected • Tooth Preparation done • Crown Adaptation done
• Weldable buccal tubes welded on buccal & Lingual surface of all crowns • Groove placement done on indicated teeth • Sandblasting of indicated crowns done with AlOxide particles of size 250μm • GIC (GC Fuji I) or RMGIC(FujiCemTM )
RECORDING THE RESULTS • Universal Testing Machine (Unitek94100 FIE,India) • Retentive Strength = load / Area (kg/cm2) • Data was analysed using ANOVA • t-test was done for pairwise comparison • SPSS statistical package was used
DISCUSSION • Mitchell et al had put forth that RMGIC offered higher retention as compared with GIC • Garcia-Godoy for the first time roughened the interior of the crown with high speed bur to create more retentive surface • O’Connor et al discovered that microblasting the internal surface of cast crowns with 50μm AlO2 improved the retention of castings luted with Zinc Phosphate 1.Mitchell CA, OrrJF, Connor KN, Magill JP, Maguire GR. Comparative study of four Glass ionomer luting cements during post pull-out tests.Dent Mater 1994;10:88-91 2.Garcia-Godoy F.Clinical evaluation of the retention of preformed crowns using two dental cements J Pedod 1984;8:278-81 3.O’Connor RP, Nayyar A, Kovarik RE. Effect of internal microblasting on retention of cemented cast crowns.J Prosthet Dent 1990;64:557-62
• Worley et al on the other hand observed that sandblasting of crown had no significant effect on retention • Rosensteil et al had stated that Adding grooves / boxes to a preparation with a limited path of withdrawl doesn’t affect its retention • Retentive grooves are generally placed proximally which significantly increase the retention of the cast crown • Potts et al had contradicted this notion in their study 1.Worley JL, Hamm RC, von Faunhofer JA. Effects of cement on crown restoration.J Prosthet Dent 1982;48:289-91 2.Rosensteil SF, Land MF, Fujimoto J. Contemporary Fixed Prosthodontics. 3rd ed. St Louis: Mosby; 2001 3.Saad AA, Claffey N, Bryne D, Hussey D. Effect of groove placement on retention/resistance of maxillary anterior resin bonded retainers. J Prosthet Dent 1995;74:133-9 4.Pal V, Shetty V, Joseph M. Comparitive evaluation of auxillary retentive feactures on retention of complete cast crowns in teeth with adequate and inadequate crown height-an in vitro study. Indian J Dent Res 1999;10:5-10
• Yilmaz et al found out that resin cement significantly improved crown retention when compared against RMGIC. However, the difference was not significant when compared against GIC. Yilmaz Y, Dalmis A,GurbuzT,Simsek S;Retentive Force and Microleakage of Stainless Steel Crowns Cemented with Three Different Luting Agents; Dental Materials Journal 23(4): 577-584, 2004
HIGHLIGHTS OF THE STUDY • Pairwise comparision of two factor interactions • Only three combinations were statistically significant viz 1.Groove & Cement 2.Groove & Sandblasting 3.Cement type & molar • In absence of groove RMGIC offers better retention than GIC • Crowns which were not sandblasted offered better retention when grooves were not given.
CONCLUSION • RMGIC can be recommended for the cementation of Stainless Steel Crowns for better retention • Grooves do not add to the retentive strength of the crowns so they can be avoided in tooth preparation of primary teeth
REFERENCES 1.Randall RC, Vrijhoef MMA, Wilson NHF. Efficacy of preformed metal crowns vs.amalgam restorations in primary molars: a systematic review. Journal of the American Dental Association 2000; 131:337-343. 2.Randall RC. Preformed metal crowns for primary and permanent molar teeth: review of the literature. Pediatric Dentistry 2002; 24(5):489-500 3.Braff MH. A comparison between stainless steel crowns and multisurface restorations in primary molars. Journal of Dentistry for Children 1975; 42: 474-8 4. Dawson LT, Simon JR, Taylor PP. The use of amalgam and stainless steel crown restorations for primary molars. Journal of Dentistry for Children 1981; 48: 420-2 5. Messer LB, Levering NJ. The durability of primary molar restorations: Observations and predictions of success of stainless steel crowns. Pediatric Dentistry 1988; 10(2):81-85. 6. Einwag J, Dunninger P. Stainless steel crown versus multisurface crown restorations: an 8 year longitudinal clinical study. Quintessence International 1996; 27: 321-3.
7.Papathanasiou AG, Curzon ME, Fairpo CG. The influence of restorative material on the survival rate of restorations in primary molars. Pediatric Dentistry 1994; 16: 282-288 8.O’Sullivan EA, Curzon MEJ. The efficacy of comprehensive dental care for children under general anaesthesia. British Dental Journal 1991;171:56-58. 9. Tate AR., Ng MW., Needleman HL, Acs G. Failure rates of restorative procedures following dental rehabilitation under general anaesthesia. Pediatric Dentistry 2002;24:1;69-71. 10.Mitchell CA, OrrJF, Connor KN, Magill JP, Maguire GR. Comparative study of four Glass ionomer luting cements during post pull-out tests.Dent Mater 1994;10:88-91 11.Garcia-Godoy F.Clinical evaluation of the retention of preformed crowns using two dental cements J Pedod 1984;8:278-81 12.O’Connor RP, Nayyar A, Kovarik RE. Effect of internal microblasting on retention of cemented cast crowns.J Prosthet Dent 1990;64:557-62
13.Worley JL, Hamm RC, von Faunhofer JA. Effects of cement on crown restoration.J Prosthet Dent 1982;48:289-91 14.Rosensteil SF, Land MF, Fujimoto J. Contemporary Fixed Prosthodontics. 3rd ed. St Louis: Mosby; 2001 15.Saad AA, Claffey N, Bryne D, Hussey D. Effect of groove placement on retention/resistance of maxillary anterior resin bonded retainers. J Prosthet Dent 1995;74:133-9 16.Pal V, Shetty V, Joseph M. Comparitive evaluation of auxillary retentive feactures on retention of complete cast crowns in teeth with adequate and inadequate crown height-an in vitro study. Indian J Dent Res 1999;10:5-10 17.Potts RG, Shillingburg HT, Duncanson MG Jr. Retention and resistance of preparations for cast restorations. J Prosthet Dent 1980;43:303. 18. Ray Stewart, Thomas Barber, Kenneth Troutman, Stephen Wei.Pediatric DentistryScientific Foundations & Clinical Practice St Louis : Mosby;1982
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