Dental Crown Selection for Patients Protected
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DENTAL CROWN SELECTION FOR PATIENTS
DR ROHAN S. VIRANI - B.D.S; M.D.S- OMMFR (MUM) Visiting dental consultant at Dr L H Hiranandani hospital, Powai. Done masters from esteemed Nair dental college & hospital, Mumbai. Author of numerous articles dental journals. Specialized in the use of dental lasers in oral lesions and aesthetic dentistry.
INTRODUCTION A crown is a type of dental restoration which completely caps or encircles a tooth or dental implant. Crowns are often needed after root canal therapy, for replacement of missing teeth (bridges) or when a very large cavity threatens the ongoing health of a tooth. Crowns can be made from many materials, which are usually fabricated in the dental lab. They are typically fixed to the tooth using a dental cement thus restoring tooth shape, size & strength. The older generation of crowns consisted of metal in some form or other i.e either complete metal crown or metal crowns with white coating over it (i.e. porcelain fused to metal crowns commonly known as ceramic crowns).
METAL CROWNS
Though metal crowns can easily withstand biting and chewing forces well, rarely chip or break they are highly unaesthetic and hence impossible to use in front teeth.
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PORCELAIN-FUSED-TO-METAL
Commonly called ceramic crowns are basically metal crowns coated with tooth colored porcelain material. The metal provides strong compression and tensile strength, and the porcelain gives the crown a white tooth-like appearance. This porcelain can be color matched to your adjacent teeth (unlike the metallic crowns). However since this crowns have metal inside they look opaque as compared to our natural teeth which have some degree of transulency. Also the metal underlying the crown's porcelain can show through as a dark line, especially at the gum line .Scientifically metal is a much less gum friendly material and microleakage around gum margins lead to gum recession over a period of time.
ALL-CERAMIC CROWNS
(Difficult to believe but upper two central incisors are metal free crowns blending imperceptibly with remaining teeth) All-ceramic are commonly called as metal free crowns. In all-ceramic crowns metal is replaced by zirconia. Zirconia crowns are custom milled from solid blocks of Zirconia and baked at extremely high temperatures so that the completed crown is near unbreakable. Zirconia is 100% biocompatible. It is inert, and the body does not reject zirconia so you don t have to worry about allergies or adverse reactions.
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ADVANTAGES OF METAL FREE CROWNS Zirconia crowns have several advantages of both traditional metal crowns and porcelain. Although metal crowns are well inexpensive & last long many patients prefer to have a natural effect that blends with the overall smile. Many also don't want metal in their mouth. Hence now, in most cases the choice will be between a ceramic fused to metal crown and a metal free ceramic/zirconia crown. Zirconia crowns have several advantages of standard porcelain crowns. Zirconia should last a lifetime (hence most manufactures provide 5 -15 year warranty) .It provides the best natural color match than any other crown type.It is also more suitable for people with metal allergies. These crowns are commonly manufactured using the CAD- CAM technology .The CAD/CAM method of fabricating all-ceramic restorations is by electronically capturing and storing a photographic image of the prepared tooth and, using computer technology, crafting a 3D restoration design that conforms to all the necessary specifications of the proposed crown.The precision & accuracy of fit of of such crowns is simply unmatched by any other technology.
COMPARISON OF METAL FREE CROWNS WITH CONVENTIONAL CROWNS
Metal crown Ceramic crown (porcelain fused to metal) Acceptable 7-12 years Over period of time Metal free crown
Aesthetics Life Marginal leakage
Poor 10-15 years Over period of time Good Poor Lost wax technique (manual) Reported
Excellent 20 years and more Rarely as manufactured by Cad Cam technology with high precision & fit Good Excellent CAD CAM high precision fit technology Uncommon
Strength Acceptabilty by gum tissues Technique
Good Poor around metal collar Lost wax technique (manual); followed by porcelain layering Reported
Allergy Warranty
Unavailable
Unavailable
5-15 years depending upon company
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CASE ILLUSTRATIONS Case 1 25 year old executive reported to our hospital with discoloured central incisors and history of trauma to upper central incisors.On examination existing huge composite filling showed microleakage and patient wanted something more natural. After vitality testing and xrays patient s consent was taken for root canal for upper central incisors followed by procera (metal free crowns- NOBELBIOCARE SWEDEN ) to give him a much more pleasing smile. BEFORE
AFTER
Note Excellent Aesthetics & Blend With Gum Margin
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CASE 2 Replacement of old unaesthetic porcelain fused to metal (ceramic) crowns with metal free crowns (LAVA 3M ESPE) BEFORE AFTER
Note micro leakage, gingival tissue recession and opaque look of old porcelain fused to metal crowns. CONCLUSION Metal based crowns and bridges were the norm in dentistry, and a standard accepted in the world without choice. But now however, we enjoy the esthetics and dependability of super-strong, excellent quality metal free crowns , such as zirconia for our modern dental restorations. Zirconia provides natural luminescent qualities and allows light and color to come through like no metal based crown and bridge ever could. Advanced CAD/CAM technology ensures that you receive an excellent fit with high end precision every time. No doubt metal free crowns are the modern day choice of crowns.
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DR ROHAN S. VIRANI - B.D.S; M.D.S- OMMFR (MUM) Visiting dental consultant at Dr L H Hiranandani hospital, Powai. Done masters from esteemed Nair dental college & hospital, Mumbai. Author of numerous articles dental journals. Specialized in the use of dental lasers in oral lesions and aesthetic dentistry.
INTRODUCTION A crown is a type of dental restoration which completely caps or encircles a tooth or dental implant. Crowns are often needed after root canal therapy, for replacement of missing teeth (bridges) or when a very large cavity threatens the ongoing health of a tooth. Crowns can be made from many materials, which are usually fabricated in the dental lab. They are typically fixed to the tooth using a dental cement thus restoring tooth shape, size & strength. The older generation of crowns consisted of metal in some form or other i.e either complete metal crown or metal crowns with white coating over it (i.e. porcelain fused to metal crowns commonly known as ceramic crowns).
METAL CROWNS
Though metal crowns can easily withstand biting and chewing forces well, rarely chip or break they are highly unaesthetic and hence impossible to use in front teeth.
1|P ag e
PORCELAIN-FUSED-TO-METAL
Commonly called ceramic crowns are basically metal crowns coated with tooth colored porcelain material. The metal provides strong compression and tensile strength, and the porcelain gives the crown a white tooth-like appearance. This porcelain can be color matched to your adjacent teeth (unlike the metallic crowns). However since this crowns have metal inside they look opaque as compared to our natural teeth which have some degree of transulency. Also the metal underlying the crown's porcelain can show through as a dark line, especially at the gum line .Scientifically metal is a much less gum friendly material and microleakage around gum margins lead to gum recession over a period of time.
ALL-CERAMIC CROWNS
(Difficult to believe but upper two central incisors are metal free crowns blending imperceptibly with remaining teeth) All-ceramic are commonly called as metal free crowns. In all-ceramic crowns metal is replaced by zirconia. Zirconia crowns are custom milled from solid blocks of Zirconia and baked at extremely high temperatures so that the completed crown is near unbreakable. Zirconia is 100% biocompatible. It is inert, and the body does not reject zirconia so you don t have to worry about allergies or adverse reactions.
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ADVANTAGES OF METAL FREE CROWNS Zirconia crowns have several advantages of both traditional metal crowns and porcelain. Although metal crowns are well inexpensive & last long many patients prefer to have a natural effect that blends with the overall smile. Many also don't want metal in their mouth. Hence now, in most cases the choice will be between a ceramic fused to metal crown and a metal free ceramic/zirconia crown. Zirconia crowns have several advantages of standard porcelain crowns. Zirconia should last a lifetime (hence most manufactures provide 5 -15 year warranty) .It provides the best natural color match than any other crown type.It is also more suitable for people with metal allergies. These crowns are commonly manufactured using the CAD- CAM technology .The CAD/CAM method of fabricating all-ceramic restorations is by electronically capturing and storing a photographic image of the prepared tooth and, using computer technology, crafting a 3D restoration design that conforms to all the necessary specifications of the proposed crown.The precision & accuracy of fit of of such crowns is simply unmatched by any other technology.
COMPARISON OF METAL FREE CROWNS WITH CONVENTIONAL CROWNS
Metal crown Ceramic crown (porcelain fused to metal) Acceptable 7-12 years Over period of time Metal free crown
Aesthetics Life Marginal leakage
Poor 10-15 years Over period of time Good Poor Lost wax technique (manual) Reported
Excellent 20 years and more Rarely as manufactured by Cad Cam technology with high precision & fit Good Excellent CAD CAM high precision fit technology Uncommon
Strength Acceptabilty by gum tissues Technique
Good Poor around metal collar Lost wax technique (manual); followed by porcelain layering Reported
Allergy Warranty
Unavailable
Unavailable
5-15 years depending upon company
3|P ag e
CASE ILLUSTRATIONS Case 1 25 year old executive reported to our hospital with discoloured central incisors and history of trauma to upper central incisors.On examination existing huge composite filling showed microleakage and patient wanted something more natural. After vitality testing and xrays patient s consent was taken for root canal for upper central incisors followed by procera (metal free crowns- NOBELBIOCARE SWEDEN ) to give him a much more pleasing smile. BEFORE
AFTER
Note Excellent Aesthetics & Blend With Gum Margin
4|P ag e
CASE 2 Replacement of old unaesthetic porcelain fused to metal (ceramic) crowns with metal free crowns (LAVA 3M ESPE) BEFORE AFTER
Note micro leakage, gingival tissue recession and opaque look of old porcelain fused to metal crowns. CONCLUSION Metal based crowns and bridges were the norm in dentistry, and a standard accepted in the world without choice. But now however, we enjoy the esthetics and dependability of super-strong, excellent quality metal free crowns , such as zirconia for our modern dental restorations. Zirconia provides natural luminescent qualities and allows light and color to come through like no metal based crown and bridge ever could. Advanced CAD/CAM technology ensures that you receive an excellent fit with high end precision every time. No doubt metal free crowns are the modern day choice of crowns.
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