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Stainless steel crown


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Stainless steel crown

  1. 1. Preformed metal crowns for primary and permanent molar teeth: review of the Stainless steel crown literature The use of stainless steel crowns 報告者:R2 王俊翔 1 2 Preformed metal crowns for primary indications for use and permanent molar teeth: review placement techniques of the literature Risks Longevity Ros C. Randall, PhD, MPhil, BChD cost effectiveness Pediatric Dentistry Vol.24 No.5 September/October 2002 utilization Pediatric Restorative Dentistry Consensus Conference 3 4 Preformed metal crowns (PMCs) Indications for use—primary PMCs for primary molar teeth were first molar teeth described in 1950 by Engel after pulp therapy The morphology of a primary molar tooth for restorations of multisurface caries and differs significantly from its permanent for patients at high caries risk successor : primary teeth with developmental defects greatest convexity at the cervical third of the crown where an amalgam is likely to fail The enamel and dentin are much thinner than fractured teeth in the permanent tooth teeth with extensive wear pulp is large with prominent pulp horns abutment for space maintainer 5 6
  2. 2. Indications for use—permanent molar teeth Pinkenon suggested that indications for interim restoration of a broken-down or placement of a PMC should include child traumarized tooth until construction of a patients who are unlikely to attend regular permanent restoration can be carried out recall appointment financial considerations teeth approaching exfoliation within 6 to teeth with developmental defects 12 months should not be fitted with a PMC restoration of a permanent molar which requires full coverage but is only partially erupted 7 8 Primary molar tooth preparation placement of wooden wedges occlusal surface: reduced by about 1.5 mm , maintaining its occlusal contour Placement procedures for primary Proximally: avoid the creation of ledges or steps molar crowns at the gingival finishing, slightly below the gingivae Lastly, ensure that all line angles are rounded Effective local anesthesia of the tooth under preparation is generally recommended 9 10 Duggal and Curzon recommended trying the selected crown for size before carrying out any lingual or buccal reduction. Selection of crown size To obtain retention, the crown must seat restore the contact areas and occlusal subgingivallyt to a depth of about 1 mm and a alignment of the prepared tooth. degree of gingival blanching seems to be inevitable trial and error A crown that is high in the occlusion (1-1.5 mm) measuring the mesiodistal dimension of is acceptable, as it is considered that primary the tooth space with dividers teeth can spontaneously adjust for this amount of measure the dimension of the contralateral occlusal discrepancy over a week tooth 11 12
  3. 3. Selection of crown size Crown modification A correctly fitting crown should snap or Crown trimming can be carried out with click into place at try-in crown scissors or an abrasive wheel More and Pink recommended a bite-wing After trimming, the crown must be crimped radiograph at the crown try-in stage to to regain its retentive contour check for any margin overextension in the Once these adjustments are completed, the interproximal area crown margins should be thinned and smoothed, final polishing being done with a rubber wheel 13 14 Cementation need a generous mix of cement to adequately fill the crown space prior to seating Placement procedures for it is recommended that the crown be first permanent molar crowns seared over the lingual or buccal wall and rolled over onto the opposite wall Once seated onto the prepared tooth, the crown should be maintained under pressure while the cement sets 15 16 Occlusion: Resin-modified glass ionomer (RMGI) Unlike the primary molar crowns, those for cement has been recommended as the permanent teeth cannot be left in hyperocclusion preferred material for cementation of When a caries lesion has extended subgingivally, permanent molar PMCs the original tooth morphology should be restored with either a bonded composite resin or an amalgam restoration before commencing the crown preparation. It is not recommended to utilize only cement in these areas. 17 18
  4. 4. Risks Periodontal concerns Periodontal concerns A well-adapted crown margin facilitates good oral hygiene and healthy gingivae, but gingivitis Nickel allergy can occur if the crown margins are inadequately Esthetics contoured or if residues of set cement remain in contact with the gingival sulcus Good- to moderate-fitting crowns seem to produce minimal gingival problems or plaque accumulation 19 20 Periodontal concerns Nickel allergy Patients in need of PMCs are likely to be The nickel content in the formulation at a moderate-to-high risk for caries, with a nickel-chromium crowns was around 70%, tendency to accumulate plaque and greater than that of contemporary stainless marginal debris. steel crowns, which contain 9%-12% A preventive regime including oral hygiene nickel, similar to that of many orthodontic instruction should be routinely included bands and wires 21 22 Esthetics Nickel allergy A well-known method of improving the 1992, Hensten-Petersen: appearance of metal crowns is to cut a The incidence of adverse reactions attributed window in the buccal wall of the cemented to orthodontic treatment is estimated as 1 in crown and to restore this with composite 100 resin 1998,Janson et al.: Carrel and Tanzilli evaluated a veneering concluded that orthodontic treatment utilizing resin for both anterior and posterior crowns: conventional Stainless Steel appliances does only 32% of the veneered crowns were intact not, in general, initiate or aggravate a nickel at 1 year, 41% having debonded and 27% hypersensitivity reaction being partially retained 23 24
  5. 5. Longevity of preformed metal crowns 25 26 From Table 1, the average failure races are around 4 times greater for amalgam compared with PMCs over approximately 5 Cost effectiveness and utilization of years preformed crowns concluding that preformed crowns are superior to Class II amalgam restorations for multisurface cavities in primary molars 27 28 Taking a hypothetical group of 100 Class II amalgam restorations and 100 PMCs in primary molars, with failure rates of 26% and 7% PMCs ($91), Class II amalgam ($55) 55 x 26 = 2.2 x(9.1x7) 29 30
  6. 6. Result PMCs are superior to amalgam restorations Dentists spend approximately 50%- 60% of for multisurface cavities in primary molar their time replacing restorations teeth Use of a well-fining PMC, where appropriate, could be expected to last the lifetime of the primary tooth 31 32 preformed metal crown (PMC) The use of stainless steel more commonly known in the United crowns States as the stainless steel crown (SSC) extremely durable relatively inexpensive N. Sue Scale, DOS, MSD subject to minimal technique sensitivity Pediatric Dentistry Vol.24 No.5 September/October 2002 during placement Pediatric Restorative Dentistry Consensus Conference offers the advantage of full coronal coverage main disadvantage: appearance 33 34 Caries risk factors This paper discusses these factors A very important consideration in Caries risk factors treatment decisions for the primary and restoration longevity mixed dentition is the future caries cost effectiveness potential of the child the best indicator for an individual's risk for future caries is his or her previous carious experience 35 36
  7. 7. Their caries risk indicators for the child at high risk include: dmfs Another factor that must be considered in the development of 2 or more lesions in 1 deciding risk-based treatment options for year carious lesions is the ability to recall the numerous white-spot lesions patient on a timely basis high titers of Streptococcus mutans the patient that is not likely to keep recall low socioeconomic strata appointments is definitely at higher risk for a history of a high frequency of sugar the sequelae to progression of caries, failed consumption restorations and new/recurrent caries 37 38 Randall,2002 literature review of studies compared the longevity of SSCs with Class II amalgam restorations The follow-up time ranged from 2 years to 10 years (mean: 5 years) Restoration longevity The failure rate of Class II amalgams ranged from 2 to 7 times that of SSCs (mean: 4 times ) SSCs are superior to Class II amalgam restorations for multisurface cavities in primary molars 39 40 The average life expectancy of Class II amalgams in all studies was approximately Cost effectiveness 2 years. Randall,2002 literature review of 5 clinical investigations when the restoration is expected/needed to comparing the failure races of SSCs with last longer than 2 years, or when the patient multisurface amalgam restorations to calculate replacement costs for the 2 types of restorations is younger than 6, best practice would be to The follow-up time ranged from 2 years to 10 choose an SSC in multisurface restorations years (mean: 5 years) of molars, in young children. The failure rate of Class II amalgams ranged from 2 to 7 times that of SSCs (mean: 4 times ) PMCs ($91), Class II amalgam ($55) (55 x 4) /9.1= 2.4 41 42
  8. 8. The most important function of the primary molars is to maintain space for the Children who require general anesthesia: permanent successors aggressive use of SSCs is suggested based Unless these broken/lost restorations are followed and replaced, many of these on their longevity and the protection their children will need orthodontics to regain full coverage provides from future caries lost space and accommodate the permanent may lengthen the time between the need for teeth. Thus the expense incurred goes far such costly and risky procedures beyond merely the cost to replace the restoration. 43 44 conclusion Children who experience approximal caries Poor children experience more caries in the primary dentition will continue to initially and are at greater risk for recurrent experience approximal caries to a greater decay because they are less likely to use extent in the mixed dentition, regardless of preventive services and keep recall socioecomonic status and recall status appointments The SSC is superior in durability and Children with maxillary anterior caries longevity to the Class II amalgam in have significantly greater risk to develop primary teeth buccal/lingual and proximal surface caries. 45 46 Dental rehabilitation under general anesthesia is expensive and places the child Recommendations at increased risk for morbidity or mortality. A primary tooth with 2 or more surfaces Children at high risk exhibiting anterior involved may receive stainless steel crowns tooth decay and/or molar caries may be if the tooth is anticipated to exfoliate in 2 treated with stainless steel crowns to or more years protect the remaining at-risk tooth surfaces Children with extensive decay, large lesions or multiple surface lesions in primary molars should be treated with stainless steel crowns 47 48
  9. 9. Recommendations Strong consideration should be given to the use of stainless steel crowns in children Thanks for your attention! who require general anesthesia 49 50 Developmental defects of teeth Amelogenesis imperfecta dentinogenesis imperfecta The rapid loss of tooth tissue results in early wear and loss of occlusal height, and can cause sensitivity in some individuals. PMCs are considered to be the treatment of choice for primary molar and permanent first molar 51