Crown Lengthening

Crown lengthening 

# Clinical crown : crown visible in oral cavity

# Anatomic crown : incisal edge till CEJ 

# Active eruption : when tooth erupts into oral cavity and reaches to occlusal level

# Passive eruption : gingival recessing down to CEJ when the tooth finish erupting 

3 things to take note in crown lengthening: biologic width, crown :root ratio, ferrule effect  

Indications of crown lengthening 

• Treatment of subgingival caries, crown or root fractures, altered passive eruption 
• Cervical root resorption
• Short clinical abutment (to provide retention for proper tooth prep)
• To produce ferrule for restoration 
• To access perforation in coronal ⅓ of root 
• To adjust gingival level for esthetics (gummy smile) 
• To relocate the margins of restorations that are impinging on biologic width (pt will complain gums keep bleeding) 
• Short teeth for esthetics 

Contraindications  

• Inadequate crown :root ratio
• Non restorable caries/root fracture
• Esthetic compromise (black triangles)
• High furcation (when molars has furcation quite coronally located) 
• Sensitivity 
• Tooth arch relationship inadequacy (occlusal space)

Restorative considerations : 

• Esthetic demand
• Function (posterior teeth – mastication) 
• Form 
• Retention 
• Marginal seal

2 methods of clinical crown lengthening 

1. Extension apically : apically positioned flap, gingivectomy 
2. Extension coronally :orthodontic/ surgical extrusion, post and core 
3. Combination of both 

Biologic width : distance between depth of gingival sulcus till crest of alveolar bone :2.04mm

So, considering 1mm of gingival sulcus + 2mm of biologic width → the distance between margin of restoration till crest of bone should be 3mm

** margin placement cannot be more than 0.5mm into the gingival sulcus to avoid damage to biologic width

If there is violation of biologic width : either tissue respond by gingival inflammation & pocket formation  OR self adjustment by body with alveolar bone loss to form back own biologic width 

Evaluation of biologic width 

1. Clinical method 

-presence of tissue discomfort when you use probe to go around the margin of restoration

-look for signs (BOP, gum inflammation, gum recession,pocket, CAL, alveolar bone loss)

• Radiographical method 

• Bone sounding / Transgingival probing 

-under LA, insert probe till crest of bone and minus sulcus depth.

-if <2mm → violation of biologic width 

Presurgical analysis: 

-determine finishing line (if cannot determine, should anticipate where it is) 

-Do bone sounding before surgery to establish biologic width 

Treatment : 

a)gingivectomy only (using electrosurgery/laser)

-if there is enough amount of sulcus depth and attached gingiva above the crestal bone 

-if there is 3mm pocket and then 2mm from base of pocket till crest of bone, so can just do gingivec

b)internal bevel gingivectomy with or without ostectomy 

-when there is enough attached gingiva after incision made 

c)apical repositioning of flap with or without ostectomy 

–** done when there is less than adequate attached gingiva 

-you wont be removing the gingiva but will just place it more below and remove the bone

d)surgical/orthodontic repositioning 

-when do gingivectomy, the gingival margins will be not harmonious causing bad esthetics 

-when there will be furcation involvement after CLP

-will need time, no tooth for some time

-C/I when inadequate anchorage to perform ortho extrusion

Cx of crown lengthening

-poor esthetics (black triangles)

-root sensitivity

-root resorption

-transient mobility of teeth

-gingival retraction (change in gingival contour)

-crown root ratio is unfavourable 

-furcation involvement

When can we give final restorations?

-6-8 weeks , provided the maintanence of pt is good, no more inflammation 

#When pt say she has redness of gums → have to evaluate whether there is poor maintanence/ violation of biologic width – remove the crown – place a temporary crown to allow area to heal for 2 weeks – reassess biologic width – if there is less distance from gingival margin to crest of bone → then will need to remove the bone to form back biologic width 

When to give temporary restoration? 

• Intraoperative (If there is less height of tooth achieved after crown lengthening, give intraoperative temp to prevent the rebound of gingiva → so that even gum rebounds, it will rebound about the margin of temp crown)
• Early 
• Delayed (if there is adequate height that is achieved, no need worry about gingiva rebound even if it occurs. Can wait for 2-3 weeks then give temp crown. Then can recall pt after 3-5 weeks to assess the healing of the area, if is ok. Then, can take imp and give permanent crown. 

If supposed to place margins subgingivally,should have

-Correct crown contour in gingival ⅓

-Correct polishing and rounding of margins

-Sufficient zone of attached gingiva

-No biological width