Effect of Metformin Gel on Guided Bone Regeneration Around Immediate Dental Implant at Posterior Maxillary Region

Dental implants are now a routine treatment option for replacing missing teeth because they restore masticatory function, preserve adjacent tooth structure, and provide favorable long-term survival when case selection and surgical execution are appropriate . After extraction, however, the alveolar ridge does not remain static. The socket undergoes dimensional remodeling, and this remodeling may affect implant position, emergence profile, soft-tissue contour, and the need for additional augmentation .

Immediate implant placement was introduced to reduce the number of surgical procedures and shorten the total treatment period. When it is performed in a suitable socket, it may also help maintain the peri-implant tissue architecture. The technique is more demanding in the posterior maxilla, where the extraction socket is often wider than the implant diameter and the native bone is commonly less dense than in other regions. These features can make primary stability, gap management, and prosthetically driven positioning more challenging .

The space between the implant surface and the socket wall, often described clinically as the horizontal gap or jumping distance, is a key biological issue in immediate implant therapy. Small gaps surrounded by intact socket walls may heal with little intervention, but wider gaps, thin buccal plates, and deficient low-density bone reduce the predictability of spontaneous bone fill. For this reason, GBR with particulate grafts and resorbable membranes is frequently used to support space maintenance, provide osteoconduction, and restrict soft-tissue invasion during bone repair.

Although GBR provides a useful scaffold for regeneration, the addition of a biologically active agent may enhance the cellular events that drive early osteogenesis, angiogenesis, and mineralization. Metformin, a biguanide drug widely used in type 2 diabetes mellitus, has attracted attention in bone-regeneration research because it can activate AMP-activated protein kinase, improve osteoblastic differentiation, reduce oxidative stress, and influence angiogenic signaling. Local delivery is clinically attractive because it can concentrate the drug at the surgical site while keeping systemic exposure minimal .

The present randomized radiographic study was therefore designed to assess whether topical 1% metformin gel, when used with GBR, improves peri-implant bone healing around immediately placed implants in the posterior maxilla. The extended 12-month analysis was added to explore whether the early radiographic bone-density response observed during osseointegration could be maintained after prosthetic rehabilitation and functional loading.

Inclusion criteria

• 1. All patients were free from any systemic diseases according to criteria of Cornell Medical Index and its modification(184).

• Patent's age at least 18 years old. 3. Patients had remaining roots or badly decayed hopeless teeth indicated for extraction for immediate implant placement in the posterior maxilla region.

• Extraction socket has sufficient bone quality and quantity amenable for implant length that is not less than 10 mm and of suitable diameter.

• The implant recipient site should be free from any pathological conditions. 6. Patients with Good Oral Hygiene, and instructed for oral hygiene measures

Exclusion criteria

• Patients with bad oral hygiene. 2. Uncontrolled systemic diseases that complicate bone healing. 3. Presence of any pathology in the implant site. 4. Heavy smokers, alcohol or drug abuse patients. 5. Patients with para functional habits such as bruxism and clenching. 6. Conditions that might lead to alteration of bone region as osteoporosis or Paget's disease.

• Any medicines such as bisphosphonates or steroids that affect bone turn over.

• History of chemotherapy or radiotherapy.