Case Report-Soft Tissue Healing in Exposed Bone Grafted Socket Using Laser-Assisted Blood Coagulation: 14 Year Review

Bone graft decontamination

The top layer of the graft material was excavated followed by decontamination of the existing bone graft with a 2940nm Er: YAG laser. The parameters were set at 100𝜇s, 70mJ, 20Hz at an average power of 1.4W. The irradiation technique was carried out using a 400𝜇m tapered sapphire tip in a scanning motion with water spray. The area was irradiated a few times in different directions and at different angles to ensure complete irradiation coverage of the surface.

Re-establishing blood clot to promote soft tissue healing

Using the above parameters and techniques, the soft tissue in and around the socket was ablated and de-epithelialized, and bleeding was induced by Er: YAG laser. An 810nm diode laser was used for coagulation & stabilization of the blood clot. Parameters were set at 20W, 20kHz, 16𝜇s. A 600𝜇m non-initiated fiber was placed at a distance of 2mm from the bleeding socket. Fixed spot irradiation for about 0.5 s produced a color change of the clot from red to pink. The technique was repeated to cover the full area. Some over-irradiated areas showed a blackened in color (Figure 4).

Figure 4: Coagulated socket by LBC technique.

Post-operative management

The patient was instructed NOT to disturb the clot with brushing, toothpaste or antiseptic mouthwash. A warm gentle saline mouth rinse was recommended. A healthy diet without spicy foods was advised. Antibiotics and analgesics were not prescribed.

Pain relief at corner of the mouth

The patient’s self-reported pain level decreased from 10 before irradiation to 2 after repeated irradiation. Mouth opening was normal, and some discomfort on full mouth opening was acceptable. Although the output power was 20W, average power was 3W. The pulse energy was 0.2mJ with energy density of the defocused beam ranging from 0.157 and 0.64mJ/cm². Therefore, the high frequency was set at 15kHz, which is warranted to yield an average power of 3W.

Re-establishing blood clot to promote soft tissue healing

The patient was reviewed after three days. The bone graft in the socket was covered with fibrin. There was bleeding on probing into the fibrin layer indicating vascular supply over the bone graft (Figure 5). Re-epithelialization across the centre of the socket buccal lingually took place on Day 17 (Figure 6). During Week 6, complete keratinization over the socket was observed (Figure 7). Peri-apical radiograph (Figure 8) and re-entry at 6 months post-op showed successful bone regeneration (Figure 9).

Figure 5:3 days post-op.

Figure 6: 17 days post-op.

Figure 7: 6 week post-op.

Figure 8: 6 months post-op radiograph.

Figure 9: Re-entry at 6 months post-op.

Er: YAG laser is absorbed well by water. Although its average power is 1.4W, the output power is calculated to be 700W. A short pulse duration with water spray allowed soft tissue ablation with low thermal conduction. The outcome effect was bleeding. If Er: YAG laser was not available, scalpel would be required to induce bleeding under local or topical anaesthesia.

810nm wavelength is absorbed well by melanin and haemoglobin. A 30W, 16𝜇s, 20kHz setting have been shown to produce a subsurface coagulation effect in non-ablative gingival depigmentation [8,9]. As irradiation was directly onto the blood clot, the same parameters with lower output power at 20W was selected. The settings generate a 0.32 mJ pulse energy with a 10 mJ/ cm2 energy density. With a 0.5 s fixed spot irradiation dosage of 100 J/cm2, an immediate surface coagulation effect was achieved. LBC coagulation provided a gelatin-like surface layer of clot. The black area of the clot showed carbonization in a thin hard layer. However, the black material can be peeled off easily, leaving the gelatinous layer below. Nevertheless, the carbonised layer provided additional protection to the clot. Laser coagulated surface is more stable than a natural formed clot.

The conventional method to re-establish primary closure by flap surgery is widely accepted. To leave the grafted site to heal would be an alternative. The advantage of LBC technique allows for soft tissue proliferation within a few days protecting the graft. This is a minimal invasive with minimal discomfort technique. There was no need for anaesthesia or medication. In cases of primary closure difficulty by flap surgery, combining LBC may assist the clinical outcome. In this case report, the patient was very pleased with the immediate ulcer pain relief and improvement in mouth opening restrictions. Patient was more confident to continue implant surgery after trouble free socket healing.

Implant placement and reviews

Implant surgery was performed on the day of re-entry. Figure 10 shows a periapical radiograph of pre-impression coping fit for a screw type crown. Ten-year review showed healthy soft tissue margin around the implant (Figure 11). Periapical radiograph at 13- year review showed good bone quality and bone level comparable to initial placement (Figure 12).

Figure 10: Radiograph at impression coping.

Figure 11: Implant/Tissue margin at 10 years review.

Figure 12: 13 years post-implant radiograph.

The laser-assisted blood coagulation technique was effective for promoting soft tissue healing on exposed bone grafted socket. It provided a good soft tissue seal for bone regeneration. LBC may be an alternative option or assistance to primary closure by flap surgery. More clinical cases are required to verify the reproducibility of this technique.

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