Indications and Regenerative Techniques for Lateral Window Sinus Floor Elevation With Ridge Augmentation

Abstract

Maxillary sinus elevation is a critical procedure in dental implantology, often necessary to address bone deficiencies in the posterior maxilla. However, various medical conditions, local factors, and surgical complexities can significantly influence the outcomes. This article delves into the implications of systemic conditions such as smoking, diabetes, osteoporosis, antiresorptive and antiangiogenic medications, radiotherapy, immunocompromised states, cardiovascular diseases, chronic alcoholism, and oxidative stress on sinus floor elevation and associated dental implant placements. Each condition presents unique challenges and necessitates tailored clinical considerations to mitigate risks and enhance surgical success. A comprehensive pre-operative assessment is essential, including detailed patient history and radiographic evaluation. Local conditions affecting the maxillary sinus, such as sinusitis, require careful examination and possible otolaryngologist consultation. The article discusses a standardized Digital Surgical Planning (DSP) protocol involving CBCT imaging, intraoral scans, virtual diagnostic wax-ups, and guided implant placement to optimize surgical planning and outcomes. Surgical techniques for lateral window antrostomy are examined, including flap design, window size and location, and piezoelectric and rotary instrumentation. Subsequent regenerative procedures involve meticulous membrane elevation and particulate graft placement, with considerations for graft material and technique to ensure stability and volume retention. Post-operative care, encompassing antibiotic prophylaxis, corticosteroid use, and decongestants, is outlined to prevent infections and manage edema. Conclusively, the article stresses the necessity for implantologists to be proficient in various techniques and make evidence-based decisions tailored to individual patient needs, ensuring optimal implant therapy outcomes. The lateral window approach remains a cornerstone of regenerative dental procedures, maintaining its significance through evolving methodologies and clinical advances. The lateral window sinus elevation procedure has demonstrated consistent success as a pre-prosthetic surgical intervention for over four decades, supported by multiple reviews. Initially a hospital-based procedure requiring autogenous bone harvesting, it has evolved into a minimally invasive, office-based procedure without the need for donor bone. Smaller access windows and flaps have further reduced morbidity. Despite the emergence of less invasive techniques such as the transcrestal approach and the use of tilted or short implants, the lateral window procedure remains relevant due to its unique advantages: Provides greater access to overcome obstacles like septa. Facilitates single-surgery management of multiple implant sites. Remains applicable regardless of residual crestal bone height. Allows intraoperative management of complications such as membrane perforations.

Keywords: alveolar ridge augmentation; complications; dental implants; sinus floor augmentation.

FIGURE 1

Radiologic sinus findings that require and does not require further investigations by otorhinolaryngologist. CT, computed tomography; otolaryngologist, ear, nose, and throat; MR, magnetic resonance; OMC, osteomeatal complex. Reprinted from Testori et al. 2023 [55] with permission from Wiley.

FIGURE 2

The Digital Surgical Planning (DSP) Protocol: CBCT scans are superimposed to the intraoral scans to produce a virtual wax‐up, the future prosthetic restoration is planned in the ideal place, then implants are placed according to the position of the prosthetic restoration. Additional hard and soft tissue grafting are then planned.

FIGURE 3

Flap management for lateral window sinus floor elevation. (a, b) Initial situation, lack of soft tissue volume on the vestibular side of the edentulous area; c) Flap design and flap elevation: Scalloped incision in the edentulous area and a vertical releasing incision positioned mesial to facilitate the flap elevation up to the antrostomy and the coronal displacement of the flap without disrupt adjacent teeth; d) Sinus elevation, with lateral antrostomy. Bone grafting was positioned before and after implant positioning to completely fill the space inside the maxillary sinus; e) Pericardium membrane on antrostomy and connective tissue graft, positioned with simple interrupted sutures anchored at the base of the de‐epithelialized anatomical papillae; f, g, h) Occlusal view of steps c, d, and e; i) Flap Suture: First intention wound closure between the buccal and palatal tissue both mesial and distal to the implant, a sling suture suspended around the healing screw can be done to further improve adaptation of the keratinized tissues of the buccal flap; j) Once the flap is sutured, the connective tissue graft remains at a position covering the implant's transmucosal portion and serves to keep the buccal flap in a coronal position by reducing its contraction; k) 3‐month healing: The keratinized tissues of the former flap are even more coronal with respect to their immediate post operative position; l) a clear demonstration of the improved volume stability provided by the underlying connective tissue graft; m, n) 1 year follow up with final screwed restoration.

FIGURE 4

The modern sinus lift flap. The modern sinus lift flap is a periodontal flap that leverages the clinical and biological principles derived from mucogingival surgery. The flap design is an envelope flap similar to the approach used in coronally advanced flap (CAF) surgery for multiple recession cases. In this case, The central axis of rotation is positioned on the canine and extends to the first incisor. No incisions are made at the sulcus or the apical margin of the recession to preserve the keratinized gingiva apical to the crown or exposed root. This tissue will be repositioned over the avascular surface of the tooth at the end of surgery. (a) At the crestal level, the incision is made as a full‐thickness cut, either mid‐crestal or palatal. Distal to the last tooth, a wide anatomical receiving papilla is created with a divergent incision extending from the center of the crest towards the distal line angle of the tooth, exiting at the sulcus; (b, c) All surgical papillae are opened using a split‐thickness approach, keeping the blade parallel to the root and exiting at the apical probing depth of the sulcus. By opening several papillae in a blunt manner, a greater connective tissue bed is created at the base of the anatomical interdental papillae. This allows for better repositioning of the primary flap onto a larger vascular surface for moving it coronally. This is particularly advantageous in the presence of adjacent mucogingival recessions, which can be addressed simultaneously [61]; (d) Where adequate surgical visibility is achieved, distal vertical release incisions are avoided. If necessary, they are confined to the keratinized tissue or performed as a split‐thickness incision in the alveolar mucosa to avoid affecting the muscular sarcolemma, thereby reducing post‐operative discomfort.

FIGURE 5

The Simplified Antrostomy design (S.A.D.). This type of antrostomy is indicated when the patient is fully edentulous or has their molars and premolars are missing. A surgical stent could be used help to proper locate the position of the anterior wall of the sinus.

FIGURE 6

Low Window Antrostomy Design. The low Window antrostomy design is a further refinement of the S.A.D. technique the antrostomy is positioned as low and as mesially as possible, the low window design offers potential benefits in reducing the risk of sinus membrane perforation.

FIGURE 7

Piezoelectric antrostomy design. The antrostomy could be made with a traditional oval shape by using diamond coated piezoelectric inserts, or it could be made with a rectangular shape with overlapping angular cuts by means of a piezoelectric saw. This technique is faster but could lead to delamination or perforation of the sinus membrane.

FIGURE 8

Window elevation. The elevation of the sinus membrane begins with the use of a trumpet‐shaped piezoelectric insert. During this phase, it is crucial to reduce the water flow intensity, as excessive water pressure can cause perforation of a thin sinus membrane. The membrane should be carefully detached until the medial wall of the maxillary sinus is reached. Once elevated, a resorbable membrane should be applied to protect the sinus membrane.

FIGURE 9

(a) a membrane is placed as a new superior wall to help contain the placed compressed bone graft; (b) The bone graft should be introduced into the sinus cavity under the most sterile conditions. Using a carrier to reduce the risk of graft infection; (c, d) If implant placement is planned during the same surgical phase, the graft should be applied to the anterior, posterior, and medial regions of the sinus, filling approximately two‐thirds of the cavity. The implants are then placed, and the remaining graft material is added to complete the filling. (e) At the end of the grafting procedure a resorbable membrane could be placed over the antrostomy to prevent graft migration, reducing soft tissue ingrowth, and supporting bone formation. Another option is to reposition the bone lid removed during a lateral sinus lift procedure. This method aims to act as a natural barrier, encouraging osteogenesis, or new bone formation, by maintaining the autogenous bone's osteoconductive properties. (f) CBCT showing the post operative result; (g) Peri‐apical radiographs at follow‐up after implant loading; and (h) final restoration at follow‐up. In clinical settings, there appears to be no significant difference in implant survival rates between the two techniques in the short term [65].