Preformed metal crowns 3

• Use?

  • hall crowns to enable no caries removal 
  • Conventional technique with complete caries removal 
  • Following a pulpotomy
• SSC lasts longer than

  amalgam, composite or GIC

  80% os SSC in place after 5 years
• SS alloy


  iron = 65-74%

  chromium = 17-19%

  nickel = 3-9%
• Shapes?

  • Anatomical
  • Pre contoured
  • Pre trimmed
  • Crimped
• Pros of SSC?

  • High success rate
  • Strong and durable
  • Malleable
  • Cost-effective
  • Single visit procedure
  • Predictable
  • Less technically demanding (Hall technique)
  • No impressions
  • No lab work
• Disadvantages of SSC?

  • Aesthetics
  • More technically demanding (conventional technique)
  • Perceived as “difficult
  • Allergies
• Indications of SSC?

  1. Primary molar with caries affecting multiple surfaces 
  2. Rampant caries 
  3. Post pulpal therapy 
  4. Developmental defects 
  5. Restoration of worn/fractures primary teeth 
  6. A space maintainer abutment 
• Absolute contraindications?

  • caries through floor of pulp chamber
  • sepsis
  • unsuccessful pulp therapy
  • close to exfoliation
  • nickel allergy
• Moderate contraindications?

  • poorly motivated child / parent
  • poor cooperation
  • multiple grossly carious teeth
• What are the two SSC techniques?

  1. conventional
  2. Hall
• conventional technique aim?

  To remove all infected carious tooth tissue and restore the tooth to function
• Why would other techniques be preferred over the conventional ?

  other techs pref for children due to the high risk of pulpal exposure and demanding nature of procedure for child and DCP
• Indications for conventional SS?

  • primary molar with caries affecting multiple surfaces
  • Rampant caries
  • After pulp therapy 
  • Developmental defects
  • Restoration of worn fractured primary teeth 
  • Space maintainer abutment 
  • Child with sufficient cooperation
• Equipment for SSC conventional tech?

  • complete set of preformed crowns 
  • Burs : short tapered diamond (633) and cylindrical diamond (541)
  • Crown scissors 
  • Crimping pliers
  • Calipers
  • Crown/band remover
  • Floss 
• Technique overview for SSC conventional ?

  1. caries removal
  2. prepare
  3. adapt
  4. cement
• caries removal for SSC?

  1. prepare child 
  2. topical anaesthesia 
  3. LA
  4. Protect airway – rubber dam?
  5. Remove caries
  6. Ensure tooth is restorable
  7. Pulpotomy if necessary
  8. Restore with GIC
• Preparation for conventional SSC?

  1. Occlusal reduction
  2. Reduce mesial & distal proximal surface
  3. Remove bulbosities / irregularities as necessary 
  4. Round off sharp edges 
• Adaptation for conventional SSC?

  • select crown - callipers to gauge id space
  • Try on tooth - lower: L -> B insertion path, upper: B -> P insertion path
  • adjust crown as required
  • Try on tooth (tight fit)
• How should crowns be adjusted?

  Contour - tooth shape

  Trim - gingival margin

  Crimp crown - at marginal edge

  
  

  Ensure to smooth after adaptation to avoid trauma at GM
• Cementation of conventional SSC?

  1. dry tooth
  2. Mix cement = clotted cream consistency 
  3. Load cement into crown 2/3 full
  4. Seat firmly 
  5. Remove excess cement
  6. Floss contact points 
  7. Check completed restoration
  8. Make pt aware you will press firmly and cement tastes bad
• why would a conventional SSC crown not seat ?

  • a proximal ledge is present rather than knife like finish
  • ledge should be removed with tapered bur
• Tooth is too long mesio ditally conventional SSC crown not seat?

  • space loss due to tooth drift into carious site
  • need to reduce tooth buccally and lingually and choose smaller crown
  • or adapt a corwn by squeezing mesio distally
• History of the hall tech?

  • technique to manage carious primary molars with no caries removal
  • Dr Norna Hill, NE scotland 1990s
  • published in BDJ 2006
• Aim of the hall tech?

  Works by removing the tooth surface from the rest of the oral environment
• Indications for hall tech?

  • Child unable to accept conventional restoration 
  • BWs available
  • No signs of infection – clinical / radiographic
  • Clear band of dentine 

  class 1:

  • non cavitated if cant accept sealant
  • cavitated if unable to accept conventional restoration

  Class 2:

  • non cavitated
  • cavitated
• Contraindications of hall technique ?

  • Irreversible pulpitis
  • Signs / symptoms of sepsis
  • Radiographic evidence of pupal involvement
  • Mobile tooth
  • Tooth close to exfoliation
  • insufficient tooth tissue to retain crown
  • Poor co-operation – risk of endangering airway 
  • Risk of IE
  • Parent / child aesthetics concerns
• Equipment for hall tech?

  • Floss
  • Separator forceps
  • Mosquito forceps (2 pairs needed)
  • Separators:
• Separators?

  1. Small brightly coloured elastic bands
  2. Used where contact points between teeth are very tight
  3. Left in place for minimum of 3 days 
  4. Creates space for crown to fit
  5. Various ways to place 
  6. Keep top loop above contact point to stop it going into GM
  7. Falls out in first 24 hours - needs to be refit
• hall technique?

  1. Ensure good understanding of child and carer 
  2. Allow child to handle crown
  3. Get them to practise biting on CWR + explain bitter taste of cement 
  4. Remove seps if used 
  5. Assess tooth shape 
  6. Protect the airway 
  7. Size the crown 
  8. Fill crown with luting cement 
  9. Seat crown and get child to bite down 
  10. Remove excess cement 
• Cautions w hall technique ?

  • occlusion: inform pt occlusal is altered temporarily, will resolve in 2wks
  • can place multiple in one apt but not two biting together as occlusion alt too harshly
  • place through tightest contact first
  • excavator ready incase placed wrong and needs to be removed before sets
  • combined technique
  • Upper Ds, try same crown from oposite side or arch to see if fits
• What should be looked for when sizing a hall crown?

  When sizing look for spring back on bulbolsity, shouldn’t just slot over 
• What hall crowns can be placed in one apt ?

  • contralateral
  • 2 uppers
  • 2 lowers
• What hall crowns cant be placed in one apt?

  • a D and E together (upper and lower)
  • no teeth biting on eachother
• hall tech overview

  • quick
  • easy to preform and tach
  • requires careful case selection
  • temp alteration of occlusion
  • preferred by clinicians, parents and kids
  • easily tolerated due to lack of LA prep and decay removal
• Conventional tech overview?

  • needs LA and prep
  • takes long time
  • needs more cooperation
  • more technically demanding
  • maintains occlusion
  • risk of iatrogenic damage
• Follow up

  Gingival response:

  • no plaque accumulation if good adaptation

  Failure:

  • decementation
  • occlusal wear or perforation (can be covered with GIC)
  • signs of sepsis

  Exfoliation:

  • occurs normally