Periodontal evaluation of crown-root fractured teeth following modified crown lengthening surgery

[Healing of the dento-gingival junction following modified crown lengthening procedure in beagle dogs]

OBJECTIVE

To evaluate the type of wound healing following modified crown lengthening surgery in dog model to provide a biological basis for its clinical application.

METHODS

Flap surgery, traditional crown lengthening procedure and modified crown lengthening procedure were performed on the right maxillary central incisor, the left maxillary central incisor and the left maxillary first lateral incisor respectively of five male beagle dogs. The right maxillary first lateral incisors with no surgical intervention were used as controls. Thirty-six weeks after the experimental procedure, tissue blocks were harvested and prepared for histological examination and analysis.

RESULTS

Histometric examination of buccolingual sections stained with hematoxylin-eosin demonstrated that the type of wound healing in the flap surgery group was re-attachment, similar to the control group. For the traditional crown lengthening surgery group, all of the five beagle dogs had lamellar cementum defects on root surface, the wound healing of four beagle dogs was new attachment accompanied by new cementum formation at cementum defect areas and the suprac-restal connective tissue was functionally oriented perpendicular to the new cementum. The wound healing of the other beagle dog was long junctional epithelial attachment, in which the junctional epithelium extended to the apical terminus of the cementum defect. In the modified crown lengthening surgery group, four beagle dogs had cementum defects on root surface (two lamellar cementum defects and two shallow platform-like cementum defects), the wound healing of three beagle dogs was new attachment, however, the supracrestal connective tissue was parallel to the root surface. The type of wound healing of another one beagle dog was long junctional epithelial attachment. Wound healing of one beagle dog in this group could not be characterized due to incomplete dissection.

CONCLUSION

Wound healing in the modified crown lengthening surgery group was similar to the traditional crown lengthening surgery group, and two types of wound healing were observed: new attachment and long junctional epithelium attachment. Neither type of root treatment procedure (root planing or root reshaping) nor root surface defect pattern (the lamellar cementum defect or shallow platform-like cementum defect) influenced the observed type of wound healing.

Success rate of fractured teeth receiving modified crown lengthening surgery and restorations

BACKGROUND

Whether to preserve a structurally compromised tooth or remove it is a dilemma often encountered by clinicians. The aim of this study was to assess the long-term success rate of fractured teeth preserved by modified crown lengthening surgery and restorations.

METHODS

Thirty-nine patients with a total of 45 fractured teeth who had received modified crown lengthening surgery were recruited and examined. Numbers of teeth lost were recorded, and the criteria for successful teeth were defined. Kaplan-Meier estimator was used to determine the success rate. Possible risk factors were compared between successful and unsuccessful groups by a Cox regression analysis to explore the potential predictors of failure with a significant level at α = 0.05.

RESULTS

The mean ± SD of success time without considering variants was 6.2 ± 0.6 years (95% CI 5.1-7.7). The mean survival rates ± SD at 1.0-, 2.0-, 3.0-, 5.0-, 7.0-, and 9.0-year intervals was 97.8 ± 2.2%, 92.2 ± 4.4%, 72.8 ± 7.9%, 68.2 ± 8.6%, 60.7 ± 10.5%, and 40.4 ± 13.6%, respectively. Failure cases in teeth with poor plaque control and step-shaped fracture margin were significantly more than those with good plaque control and knife-shaped fracture margin (HR = 7.237, p = 0.011; HR = 15.399, p = 0.006; respectively).

CONCLUSIONS

Fractured teeth treated with modified crown lengthening surgery are anticipated to have a high clinical success rate for 6.2 ± 0.6 years. Plaque control and fracture morphology appeared to be significantly associated with the success of the multidisciplinary treatment approach.

The management of a complicated crown-root fracture incorporating modified crown-lengthening surgery

Anterior teeth with subgingival fractures require a multidisciplinary management approach with regards to biological, functional and aesthetic factors. This case report emphasises the use of a minimally invasive technique combined with a sequence of therapies to treat a complicated crown-root fracture and reviews the critical factors to ensure predictable outcomes. Endodontic treatment was undertaken due to exposure of the pulp in a complicated crown-root fracture of the maxillary right central incisor. Extrusion of the fractured fragment was performed to expose the fracture margin under the alveolar bone. Modified crown-lengthening surgery was used to reconstruct the biologic width. The traumatised tooth was restored with a glass fibre post and resin core, which fit the biological requirements. Finally, an all-ceramic crown fulfilled biomimetic aesthetics. This multidisciplinary approach achieved a good long-term prognosis with regards to periodontal and periapical healing.