Adjuvant surgical procedures for implants in anterior maxilla: A case series

Introduction

Dental implants have been in service for almost 3 decades now. Offering many obvious advantages in terms of chewing efficiency and esthetics over their counterparts, namely dentures and fixed bridges, they have been the workhorse for replacing missing teeth in patients for dental professionals across the globe now.

The global dental implants market was estimated to be $3.74 billion in 2021 and is expected to reach $5.71 billion in 2028 at a CAGR of 6.2% in forecast period, 2021-2028.(1)

However there are multiple scenarios where straightforward routine dental implant placement is precluded by patient conditions like less than ideal bone conditions, proximity to anatomical landmarks, etc. This is where adjuvant procedures for implants come in in ensuring long term success of the treatment and patient satisfaction. Based on clinical experience, the minimum dimensions in the maxilla to insert a dental implant are an alveolar ridge width of 5 mm and a bone height of 10 mm. Any deficit in these dimensions predisposes the risk of placement in anatomically unfavorable positions and thus leading to implant failure. Therefore, various surgical techniques have been employed to augment the bone volume. Ridge augmentation techniques include the use of bone grafts, guided bone regeneration with bio-resorbable or non-resorbable membrane, alveolar distraction osteogenesis and ridge splitting. In this article we will overview the 2 most commonly used procedures:-

1. 1. Guided bone regeneration
   2. Chin graft

Guided bone regeneration (GBR):

GBR’s main use belongs in periodontology for gingival grafts and wall defects of tooth socket. It is extended in implants to cover up for the lost gingival wall, most commonly being the labial wall. Rationale Bone width being inadequate, GBR addresses to increase it by adding a bone graft material directly over the host bone, then covering it with a barrier membrane. This is done to prevent soft tissue ingrowth over the bone graft added over the site. Before the bone graft is added, small bur holes are made over the host bone to make it bleed and rough, to increase surface area and increase wound healing speed, called as “Regional acceleretory phenomenon”. The important determinants of the success of the procedure is

1. 1. • absence of mobility of the barrier membrane
      • good closure with a hermetic seal
      • infection control

Technique 1. Recipient site usually is the anterior maxilla in which labial plate shows deficient width with implant exposure. (Figure 1)

Figure 1: Recipient site showing exposure of implant threads due to inadequate bone thickness 2. A 8 no round diamond bur or 703 carbide bur is used to make small punches in the host wall proportional to the area to be grafted. It is important to observe bleeding at this stage: LESS OR ABSENCE OF BLEEDING points to necrotic bone (osteomyelitis, long term bisphosphonate therapy) and can indicate poor prognosis or failure. 3. Once the host bone is prepared, demineralized freeze dried-bone (DFDB) or particulate bone matter is applied over the area to achieve desired thickness (Figure 2).

Figure 2: DFDB applied over exposed implant surfaces It is at this stage that overpacking is done to counter graft shrinkage (2) when using cancellous type of particulate bone. Another study says overpacking is needed only for particulate bone and not the cortical bone (3)

Important Tip>>> After incision, proper underming and exposure of the soft tissue to desired vestibular depth is done to ensure adequate movement of the soft tissue. This is important to accommodate the additional dimension of the graft later.

4. To make the bone graft homogenous and easier to handle, various substances are used like PRF membrane and or direct use of commercially available calcium phosphosilicate (CPS) (Novabone) particles in a bimodal size distribution combined with a polyethylene glycol and glycerine binder. 5. Once this is done, a collagen membrane is placed over the graft and carried to the depth of the gingival flap. It is secured to the depth with horizontal mattress suture taking the bite from the depth of the soft tissue, passing it through the membrane, bringing back to the coronal side and closing (Figure 3) before final closure with non-resorbable suture (prolene 3-0).(Figure 4)