title: Maxillary Sinus Augmentation - a histological, clinical, radiographic and patient centred assessment
Creators: name: Alayan, Jamil
Publisher: name: Griffith University
Year: 2018
Subjects: subject: Maxillary sinus augmentation
subject: Posterior maxilla
subject: Dental implant
subject: Bone grafts
subject: Collagen stabilized ABBM
subject: Single crowns
subject: Partial dentures

description: Maxillary sinus pneumatization is a frequently encountered problem in the dental implant rehabilitation of the posterior maxilla. Maxillary sinus augmentation (MSA) using a lateral wall approach is a well-established and commonly utilized surgical technique for overcoming this bone deficiency and allowing implant placement. MSA is still in the refinement process with a large degree of variation in all aspects of the technique including; the surgical protocol, the anatomical site, the choice of material, the site of autogenous bone harvesting, the timing of implant surgery and the use of barrier membranes. Generally, however, prospective controlled clinical trials critically assessing these domains remain rare, especially studies applying well defined success criteria for implant supported restorations placed in sites of MSA. The maxillary sinus grafting procedure is invasive and surgically demanding, but appears to have limited interference with maxillary sinus physiology when performed well. In addition, reported surgical complications are generally well tolerated and followed by normal recovery in the vast majority of cases. Most of this data however is derived from medium to low level evidence (clinical case series, retrospective analyses). Patients undergoing this procedure also expect to be counselled about their expectations regarding pain and the impact of this procedure on their daily life in the post-operative period. Such information is not available. There is also limited long term outcome data on implants placed in MSA. Historically, autogenous bone grafts have been considered the gold standard due to their inherent osteoinductivity. Their significant limitations in MSA however has driven intense research into various bone substitutes. Anorganic bovine bone mineral (ABBM) is a very well documented xenograft in MSA when used alone or as a composite graft with autogenous bone (AB) (ABBM + AB). More recently, collagen stabilized ABBM using 10% porcine type-1 collagen matrix has also become available for use (ABBM-C) (Bio-Oss Collagen®). This formulation may have clinical utility in its use as a sole biomaterial in MSA especially in situations of Schneiderian membrane perforation. There are however, no published studies on this grafting material in MSA. Whilst material selection influences the histological appearance and characteristics of the regenerated bone, other factors can also play a role including defect anatomy and implant surface. Chemical modification of implant surfaces has resulted in a surface with increased surface energy and hydrophilicity (SLActive®). These surfaces have demonstrated enhanced bone apposition during the early stages of osseointegration and improved bone regeneration in bone defects when compared to traditional microrough implant surfaces (SLA®). To date however, very few studies have compared these two implant surfaces in MSA and none at the early stages of osseointegration. As such, this thesis aims to assess the histological, clinical (surgical), volumetric and patient centered outcomes of ABBM-C in MSA when compared to ABBM + AB. In addition, the influence of implant surface microtopography on early osseointegration in MSA regenerated sites was assessed. This is continued further to assess the outcomes of implant supported restorations placed into MSA sites using these two biomaterials and well defined success criteria including survival, biological and technical outcomes. In the first part of the thesis, qualitative and quantitative histological assessment was used to compare ABBM-C with ABBM + AB in both pre-clinical and clinical MSA models. In the first experimental chapter (Chapter 2), a randomized controlled trial utilized histomorphometric assessment in a pre-clinical model (ovine) to show that both healing time and proximity to the resident sinus walls had a positive impact on histomorphometric outcomes. Both biomaterials exhibited very similar histomorphometric parameters in the proximal zones but the presence of AB seemed advantageous in regions distant from resident sinus wall. In chapter 3, the histomorphometric assessment was performed in a prospective controlled clinical trial. Both biomaterials exhibited very similar histomorphometric parameters but the ABBM+AB group exhibited a more mature graft with a greater proportion of lamellar bone. Based on these histological assessments, ABBM-C appeared to be a suitable bone substitute for the purposes of MSA. In chapter 4, the influence of implant surface microtopography on early osseointegration in MSA was assessed in a pre-clinical (ovine) model by placing implants with a hydrophilic and hydrophobic surface in sites previously receiving the MSA procedure. Both time and the use of a hydrophilic implant surface had a positive impact on %BIC around implants placed into augmented maxillary sinuses. Hydrophilic implant surfaces also had a positive impact on the surrounding tissue composition. The second part of this thesis explores the clinical, radiographic and patient centred outcomes of MSA using these two biomaterials, as well as the survival and success of the implant supported restorations placed into these sites. In chapter 5, a prospective clinical trial compared both groups of biomaterials in MSA with material allocation based on specific clinical presentations (sinus membrane perforation / local AB bone availability). It indicated that MSA using the lateral wall technique is safe and associated with mild to moderate pain and restrictions to daily activities for 48-72hrs. Patient reporting of morbidity was greater with AB harvesting. Volumetric analysis using 3-D imaging showed that C-ABBM provides comparable bone volume to AB + ABBM that is sufficient for placement of implants of adequate size with no need for further vertical augmentation. Engaging the surrounding sinus walls had a significant positive impact on graft volume. In chapter 6, the same patient population was followed to assess implant supported restorations after 12 months of function using well defined success criteria. Both groups revealed high implant survival rates. Marginal bone levels &amp; peri-implant parameters were consistent with health in both groups. The majority of the restorations were screw retained single crowns or small fixed partial dentures. The incidence of mucositis was dependent on the definition threshold. Absence of periimplantitis and low rates of technical complications were reported in both groups. Within the limitation of this trial, it can be concluded that collagen stabilized ABBM can be successfully used alone for maxillary sinus augmentation and subsequent implant rehabilitation. Its clinical utility is most relevant in cases of sinus membrane perforation and insufficient autogenous bone in the local area.