Tips on crown lengthening
Radiographic planning is best done with a CBCT with the lips retracted and tongue off the palate. This will allow a view on a lateral view that will define the gingival soft tissue and the thickness of the palate if a connective tissue graft is needed. It will show on a lateral view the location of the CEJ and how much enamel is hiding under the gingiva.
The amount of crown lengthening that can be done is limited by the aesthetics i.e the length- width ratios (usually around 80%) and the biology of the patient.
Depending on tooth positions, you may not only be discussing crown lengthening. If the amount of gingiva to be reduced exposes the crown only with good symmetry between the inclination of teeth then the treatment plan may be crown lengthening only. However if there is significant asymmetry, orthodontics can be considered. If the crown lengthening exposure the root of the tooth you may also be considering crowns or veneers. Pre surgical planning is essential.
Bony exostoses are important as it can cause an inflection in the smile of the patient. When the patient smiles it flips over the exostoses and movs more apically than it should. after removal, it will allow the lip to rest 1-2mm lower than before.
Arranging the zenith points can mask different angulations of teeth. design the zeniths slightly to the distal of the midline to imply a mesially tipped tooth.
Use the incisal edge as the reference point to design the final gingival margin as a guide for intrasurgery measurements. Once the flap is raised, the original gingival margin will be lost and you will have no reference.
Calipers can be used before surgery to transefer the information from DSD and the CBCT to mark the gingiva at the final desired gingival margin.
Biologic width on average is 2.8mm. However averages are misleading as they match no one in particular. There is wide variation in the biologic width with different biootypes. Thick biotypes require a wider biologic width and thin biotypes require a wider margin. Therefore, thicker biotpyes require more bone removal vertically from the desired gingival margin.
Thin biotype 2-2.5mm, thick biotype >=3mm
Identifying the biotype can be done by inserting a perio probe into the gingival margin. Thin biotypes will show through the translucent gingiva. >2mm thickness will mask the metal of the probe. A probe can be used horizontally and compress the gingival margin slightly to actually measure the width of the gingiva.
The initial incision for the gingival margin is different for different biotypes. Thick biotypes benefit from an incision bevelled 40 degrees apically to thin out the gingival margin. a 90 degrees horizontal cut will result in a very thick margin. A thin biotype that is bevelled may necrose at the margin due to its thinness. A thin biotype will benefit from a 90 degree initial incision.
Only raise the flap coronal to the mucogingival line. This keeps the muscular attachments in place and improves post op stability. If you raise the flap too high, any muscular movements will move the flap from its final place. Keeping the muscles intact results in less swelling, bleeding, pain and more recession post operatively.
If there is insufficient height of attached gingiva to allow gingivectomy, your only option is an apically repositioned flap which does require you to raise a full flap past the mucogingival line.
General steps on gingivectomy
1. Gingivectomy to remove the excess gingiva keeping the same shape as the smile design. In thicker biotypes, it is not essential to get a perfect contour as this can be refined later with electrosurgery or laser. The gingiva will fall into place once the bone has reduced.
2. Raise a full flap
3. Adjust the contour of the bone to follow the contours of the root using a fine diamond large round in a surgical handpiece.
4. Remove height of bone to match the biological width desired. This will determine the final position of the gignival margin. The desired shape of the soft tissue must be reflected in the bone crest. This includes the zenith point. Add the desired biologic width to the preop measurements in calipers.
5. Suture the flap to the palatal gingiva
6. Refine the margins with a laser or electrosurgery.
The amount of crown lengthening that can be done is limited by the aesthetics i.e the length- width ratios (usually around 80%) and the biology of the patient.
Depending on tooth positions, you may not only be discussing crown lengthening. If the amount of gingiva to be reduced exposes the crown only with good symmetry between the inclination of teeth then the treatment plan may be crown lengthening only. However if there is significant asymmetry, orthodontics can be considered. If the crown lengthening exposure the root of the tooth you may also be considering crowns or veneers. Pre surgical planning is essential.
Bony exostoses are important as it can cause an inflection in the smile of the patient. When the patient smiles it flips over the exostoses and movs more apically than it should. after removal, it will allow the lip to rest 1-2mm lower than before.
Arranging the zenith points can mask different angulations of teeth. design the zeniths slightly to the distal of the midline to imply a mesially tipped tooth.
Use the incisal edge as the reference point to design the final gingival margin as a guide for intrasurgery measurements. Once the flap is raised, the original gingival margin will be lost and you will have no reference.
Calipers can be used before surgery to transefer the information from DSD and the CBCT to mark the gingiva at the final desired gingival margin.
Biologic width on average is 2.8mm. However averages are misleading as they match no one in particular. There is wide variation in the biologic width with different biootypes. Thick biotypes require a wider biologic width and thin biotypes require a wider margin. Therefore, thicker biotpyes require more bone removal vertically from the desired gingival margin.
Thin biotype 2-2.5mm, thick biotype >=3mm
Identifying the biotype can be done by inserting a perio probe into the gingival margin. Thin biotypes will show through the translucent gingiva. >2mm thickness will mask the metal of the probe. A probe can be used horizontally and compress the gingival margin slightly to actually measure the width of the gingiva.
The initial incision for the gingival margin is different for different biotypes. Thick biotypes benefit from an incision bevelled 40 degrees apically to thin out the gingival margin. a 90 degrees horizontal cut will result in a very thick margin. A thin biotype that is bevelled may necrose at the margin due to its thinness. A thin biotype will benefit from a 90 degree initial incision.
Only raise the flap coronal to the mucogingival line. This keeps the muscular attachments in place and improves post op stability. If you raise the flap too high, any muscular movements will move the flap from its final place. Keeping the muscles intact results in less swelling, bleeding, pain and more recession post operatively.
If there is insufficient height of attached gingiva to allow gingivectomy, your only option is an apically repositioned flap which does require you to raise a full flap past the mucogingival line.
General steps on gingivectomy
1. Gingivectomy to remove the excess gingiva keeping the same shape as the smile design. In thicker biotypes, it is not essential to get a perfect contour as this can be refined later with electrosurgery or laser. The gingiva will fall into place once the bone has reduced.
2. Raise a full flap
3. Adjust the contour of the bone to follow the contours of the root using a fine diamond large round in a surgical handpiece.
4. Remove height of bone to match the biological width desired. This will determine the final position of the gignival margin. The desired shape of the soft tissue must be reflected in the bone crest. This includes the zenith point. Add the desired biologic width to the preop measurements in calipers.
5. Suture the flap to the palatal gingiva
6. Refine the margins with a laser or electrosurgery.
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