Application of Injection Overmolding Process to Restore Fractured Tooth
A 96-year-old male patient presented for repair of a broken tooth on his upper removable partial denture (Figure 1). On examination, we determined that he had not broken a tooth off his appliance, but had instead broken one of his natural teeth, tooth No. 7 (Figure 2). He stated he was eating when it broke off. We discussed the possible treatment options, which included removal of the tooth and adding to the existing appliance. Other options included rebuilding the tooth structure, and of course, no treatment at all. The patient asked if it were possible to restore the tooth, and we determined that it could be done.
After administering a local anesthetic that was buffered with OnSet Local Anesthetic Buffering System (Orapharma), we placed the upper denture back into place after minor modification of the lingual aspect to make room for the composite buildup we were about to create. We then placed an Isolite Dental Isolation device (Isolite Systems) to help him keep his mouth open during the procedure and provide good isolation of the area. We then tried in and contoured BioClear matrixes (BioClear Matrix Systems) on the mesial and distal aspects of tooth No. 7 to create complete enclosure for an injection overmolding process used with the BioClear System (Figure 3).
The tooth was then etched with a 37% phosphoric acid, contained within the BioClear matrices, for 10 seconds and then the tooth was rinsed and dried, maintaining the matrices in place (Figure 4). ALL-BOND UNIVERSAL (BISCO) was then placed onto the enclosed tooth and matrix system and cured, as directed by the manufacturer for total etch use. Next, ACTIVA Bioactive (Pulpdent) restorative material shade A 3.5 was injection overmolded into the “aquarium” created by the BioClear System (Figure 5) to bulk-fill the area. The material was then cured. The BioClear matrices were removed and the buildup was trimmed and contoured with Super Snap Discs (Shofu) and NeoBurr 12 blade esthetic finishing burs (Microcopy Dental) to shape and contour, followed by polishing with Gazelle Satin and Hi-Gloss polishers (Microcopy Dental) (Figure 6) to bring out the high luster of the restoration. The denture was removed and then placed to assure that the new restoration would not interfere with form and function.
The immediate finished result, although a bit lighter than we would have liked, was very pleasing to the patient (Figure 7). He has been smiling ever since.