Research Article | Open Access

¹Department of Periodontics, United States Army Dental Health Activity, Fort Jackson, SC, USA
²Private Practice, McKenzie Periodontics and Implant Dentistry, Columbia, SC, USA
³Department of Periodontics, United States Army Dental Health Activity, Fort Riley, KS, USA
⁴Department of Periodontics, United States Army Dental Health Activity, Fort Wainwright, AK, USA
⁵Department of Prosthodontics, Army Postgraduate Dental School, Postgraduate Dental College, Uniformed Services University, Fort Eisenhower, GA, USA
⁶Department of Periodontics, Army Postgraduate Dental School, Postgraduate Dental College, Uniformed Services University, Fort Eisenhower, GA, USA

*Corresponding author: Thomas M Johnson, Department of Periodontics, Army Postgraduate Dental School, Postgraduate Dental College, Uniformed Services University, Fort Eisenhower, GA, USA

Abstract

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Objective: Immediate implant placement into a molar extraction socket may hasten return to masticatory function and reduce overall treatment time. Placement of a graft or biomaterial in the peri-implant gap defect (PGD) has been associated with superior treatment outcomes. The purpose of this report is to present four cases demonstrating use of laser-generated blood clots to stabilize freeze-dried bone allografts (FDBAs) at molar immediate implant sites.
Methods: Four patients with non-restorable mandibular first molars presented to the Department of Periodontics, Army Postgraduate Dental School, Uniformed Services University, Fort Eisenhower, GA, USA. The hopeless teeth were extracted without flap reflection, and dental implants were installed in each socket. FDBAs were applied in the PGDs. In one case, a cover screw was utilized, and the implant was submerged under a laser-generated clot. In the remaining cases, transmucosal healing abutments were installed.
Results: Favorable healing was observed in all cases, each patient reporting minimal discomfort limited to the first two postoperative days. At the submerged implant site, > 2 mm buccal bone thickness was noted at re-entry. In the remaining cases, keratinized peri-implant mucosa was in contact with the healing abutment at the one-week follow-up appointment. All implants exhibited interproximal radiographic bone levels coronal to the first implant thread at every follow-up assessment.
Conclusions: Whether infrared lasers enhance healing at immediate implant sites remains an open question in implantology. However, the presented cases demonstrate that a neodymium-doped yttrium aluminum garnet laser can reliably stabilize particulate bone allografts in PGDs at immediate implant sites exhibiting large horizontal defect dimensions.
Keywords: Tooth Loss; Dental Implants; Allografts; Lasers; Clinical Protocols; Treatment Outcome
Abbreviations: PGD: Peri-Implant Gap Defect, FDBA: Stabilize Freeze-Dried Bone Allografts, IIP: Immediate Implant Placement, Nd: YAG: Neodymium-Doped Yttrium Aluminum Garnet, FDBA: Freeze-Dried Bone Allograft

Background

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Clinicians widely acknowledge that immediate implant placement (IIP) in the esthetic zone is a predictable therapy with the potential to enhance—or even optimize—clinical and patient-oriented outcomes, assuming appropriate case selection and careful technique [1-4]. However, advantages such as early return to masticatory function, reduced number of procedures, and high patient acceptance have also been attributed to IIP at molar sites [4-6]. A recent systematic review by Ragucci and colleagues reported 1-year molar immediate implant survival and success rates reaching 97% and 93%, respectively, although evidence supporting molar IIP remains mostly limited to case series [4-6]. Superior treatment outcomes have been associated with flapless surgery, graft placement in the peri-implant gap defect (PGD), one-stage implant placement, and allowance for a healing period without loading [4,6]. The purpose of this report is to present a technique for stabilizing graft material in PGDs at molar immediate implant sites using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser.

Materials and Methods

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Patients in this report presented to the Department of Periodontics, Army Postgraduate Dental School, Postgraduate Dental College, Fort Eisenhower, GA, USA, and completed an informed consent process involving verbal and written components. Each patient elected IIP at a mandibular first molar site.

Case 1
A healthy female aged 51 years presented in December of 2021 with a non-restorable, fractured tooth #30. The tooth was removed without flap reflection, and a ø5 x 11.5 mm implant (Nobel Replace Conical Connection, Nobel Biocare, Zurich, Switzerland) was placed with insertion torque of 45 Ncm. A ø5 x 5 mm healing abutment was applied, and a freeze-dried bone allograft (FDBA) (Oragraft, LifeNet, Virginia Beach, VA, USA) was placed in the PGD. An Nd:YAG laser (3.6W, 550 μs, 20 Hz, 30 J applied) was used to establish a stable clot to contain the FDBA particles. Additionally, the operator applied 380 J (3.0W, 100 μs, 20 Hz) to the facial, occlusal, and palatal/lingual aspects of the site, with the fiber located ≈ 2-3 cm above the tissue (Table 1). Ibuprofen (400 mg) and acetaminophen (325 mg) were prescribed for analgesia, as needed, and chlorhexidine mouth rinse was used for plaque control until normal oral hygiene practices could be reinstated. Early healing was uneventful, and minimal changes in buccal alveolar ridge and mucosal contours were observed from baseline through definitive restoration (Figs. 1 and 2). After 22 months of follow-up, interproximal radiographic levels were at or beyond the polished collar of the implant.

Case 2
A healthy female aged 31 years presented in February of 2019 with a fractured fixed dental prosthesis (#30-#32) and minimal clinical crown height at tooth #30, which also exhibited failed root canal therapy (Fig. 4). Following extraction of tooth #30, an intact buccal cortex was noted. A ø5 x 13 mm implant (Nobel Replace Conical Connection, Nobel Biocare) was installed with a 35-Ncm torque, and a ø5 x 5 mm healing abutment was applied. The PGD received particulate FDBA (Oragraft, LifeNet), and a laser-generated clot was established using parameters described in Table 1 with a total of 374 J delivered (Fig. 3). Postoperative analgesics and oral hygiene instructions were also as described in Case 1. However, the patient additionally received amoxicillin (500 mg) three times daily for one week.
Early healing was uneventful. The definitive implant-supported restoration was delivered at postoperative week 16 (Fig. 4). After 3 years of follow-up, radiographic peri-implant bone levels appeared favorable (Fig. 5).

Case 3
A healthy male aged 25 years presented in April of 2022 with a fractured restoration and recurrent caries on tooth #19 (Fig. 6). After minimally traumatic extraction of tooth #19, a ø5 x 13 mm implant (Nobel Replace Conical Connection, Nobel Biocare) was placed with > 35 Ncm torque, and a ø5 x 5 mm healing abutment was applied. A particulate FDBA (Oragraft, LifeNet) was implanted in the PGD, and a laser-generated clot was established using the parameters described in Table 1, a total of 382 J delivered (Fig. 7). Analgesics and oral hygiene instructions were as described in Case 1. The patient received amoxicillin (500 mg) three times daily for one week, and healing progressed uneventfully. At postoperative month three, a provisional restoration was delivered. After 16 months of follow-up (Fig. 8), interproximal radiographic bone levels were at or coronal to the polished collar of the implant.

Case 4
A healthy male aged 44 years presented in May of 2022 with caries at tooth #18 (mesial) and recurrent caries at tooth #19 with evidence of failed root canal therapy. After extraction of tooth #19, a ø6.0 x 13 mm implant (Nanotite Tapered Certain, ZimVie, Warsaw, IN, USA) was installed (25 Ncm torque). The PGD received a particulate FDBA (Oragraft, LifeNet), and a laser-generated clot was established using the parameters described in Table 1, a total of 582 J administered (Fig. 9). Healing progressed uneventfully, and three months following implant placement, a ø6 x 5 mm healing abutment was inserted (Fig. 10). After 12 months of follow-up, radiographic peri-implant bone levels remained coronal to the first implant thread.

Results and Discussion

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The objective of this report was to demonstrate use of laser-generated blood clots to stabilize FDBAs in PGDs at molar immediate implant sites. In all cases, early healing was favorable, and radiographic bone levels remained at or coronal to the first implant thread after 1 to 3 years of follow- up. Large PGD size is a feature distinguishing molar from non-molar immediate implant sites. Various approaches to PGD management at molar sites have been reported—no graft placement [7] or use of a dense polytetrafluoroethylene membrane [8], an absorbable membrane [9], a connective tissue graft [10], platelet rich fibrin [11], or granulation tissue obtained from the socket [12] to stabilize the graft/biomaterial. In each presented case, laser use to generate a blood clot required only 2 to 3 minutes, and each clot reliably contained the FDBA. Subjectively, healing of the peri-implant mucosa appeared advanced at the one-week assessment in each case.
Limited evidence from in vitro and animal studies has led to hypotheses that infrared laser energy stimulates osteoprogenitor cells [13], enhances bone regeneration [14], and improves osseointegration of dental implants [15]. Enhanced healing at immediate implant sites receiving infrared laser application has not been demonstrated in controlled clinical studies. However, the described clinical protocol is convenient and well accepted by patients. Previously, laser-generated clots were found to effectively contain bone biomaterials in PGDs at anterior and premolar immediate implant sites [16]. Despite the large horizontal defect dimensions encountered at molar immediate implant sites, Nd:YAG lasers appear to reliably establish clots that stabilize FDBA in the PGDs, based on observations from the presented cases.
This consecutive case series represents the first report demonstrating containment of a particulate bone biomaterial in PGDs at molar immediate implant sites using laser clot stabilization. Previous authors have suggested that infrared laser radiation may stimulate cells involved in hard and soft tissue healing. Whether Nd:YAG laser use at immediate implant sites enhances the clinical outcome remains unknown. However, the cases presented herein demonstrate that laser-generated blood clots reliably produce immediate graft containment and graft stability through the early postoperative period. Use of the laser to dry the pooled blood (3.0 W, 100 µs, 20 Hz, noncontact) appears essential for increasing clot stability. Controlled clinical research validating the presented technique is needed.

Acknowledgements
The authors gratefully recognize the prosthodontists who provided restorative treatment in the presented cases: Dr. Kellie S. O’Keefe (Case 2), U.S. Army Dental Health Activity, Fort Wainwright, Alaska, USA, and Dr. Kevin M. Lassiter (Case 4), U.S. Army Dental Health Activity, Fort Stewart, Georgia, USA.
Disclaimer: The views expressed in this manuscript are those of the authors and do not necessarily reflect the official policy of the United States Government, the Department of Defense, the Defense Health Agency, the Department of the Army, the United States Army Medical Department, or Uniformed Services University of the Health Sciences.
Author contribution statement: All authors have contributed substantially to conceptualization of the article, writing the original draft, critical review, and editing. All authors have approved the final version of the manuscript.
Disclosure statement: The views expressed in this manuscript are those of the authors and do not necessarily reflect the official policy of the United States Government, the Department of Defense, the Defense Health Agency, the Department of the Army, the United States Army Medical Department, or Uniformed Services University.
Conflict of interest statement: The authors report no financial, economic, or professional interests that may have influenced the design, execution, or presentation of this work.
Funding: The authors report no extramural funding for this work.

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