CC
A 39-year-old male patient was referred to the authors’ outpatient clinic to restore the posterior right maxillary region. His chief complaint was that he could not chew well.
HPI
The patient is seeking treatment for replacement of his missing teeth, preferably a fixed type of dental restoration to improve masticatory efficiency. He lost his upper right first premolar, second premolar, and first molar about 4 years ago because of failed endodontic treatment. Early loss of posterior maxillary teeth is associated with increased pneumatization of the maxillary sinus, and frequently inadequate bone for satisfactory implants does not exist below such a sinus.
PMHX/PDHX/medications/allergies/SH/FH
His medical history is noncontributory. Inadequately controlled conditions, such as diabetes mellitus, immunodeficiencies, or any condition interfering with implant integration, must be taken into account. The patient’s main complaint and expectations of treatment are paramount. Social history (drinking, recreational drug use, and smoking) should be addressed because they can increase implant failure. Cigarette smoking (nicotine) increases platelet adhesiveness, raises the risk of microvascular occlusion, and causes tissue ischemia. Tobacco smoking causes catecholamine release and associated vasoconstriction, resulting in decreased tissue perfusion. Smoking is additionally believed to suppress the immune responses by affecting the function of neutrophils. A perioperative smoking cessation program has been shown to reduce respiratory and wound-healing complications. Good health care mandates smoking cessation in any patient, and the possibility of an increased risk of failure of osseointegration in smokers should be discussed with the patient and included in the consent as a shared liability. Immunosuppressants and mediations that affect bone healing can compromise integration. Dental hygiene, including plaque management, should be addressed before implant surgery.
A history of acute or chronic sinusitis may be problematic for an implant surgery with an associated sinus graft procedure planned. Prolonged inflammation or infection creates an inappropriate environment for the procedure. Maxillary sinusitis results from a secondary bacterial infection of an obstructed sinus. Mucosal edema, increased mucous production, bacterial accumulation, and inflammatory debris associated with sinusitis create an unfavorable environment for surgery and subsequent healing. Infections of the maxillary sinus after sinus grafting surgery occur in a small percentage of cases and are usually managed conservatively, with preservation of uninfected graft and subsequent implant success. The two most common bacteria involved in acute maxillary sinusitis are Haemophilus influenzae and Streptococcus pneumoniae. Staphylococcus aureus, α-hemolytic streptococci, and Bacteroides and Pseudomonas spp. are most frequently found in chronic bacterial sinusitis. Any form of sinus infection should be treated with decongestants and antibiotics, and some infections require functional endoscopic sinus surgery before performance of a sinus grafting procedure can be contemplated. A broad-spectrum antibiotic, such as amoxicillin with clavulanic acid (Augmentin), is often the initial antibiotic used in the management of infections caused by nasal or sinus flora.
Examination
The extraoral examination showed no abnormalities, including swelling or facial asymmetry, and the tissue overlying the left sinus and the zygomatic area looked normal. The intraoral examination revealed edentulous right posterior maxilla with adequate oral hygiene. Only mild plaque-induced gingivitis was present, especially in the anterior maxilla. Dental caries, soft tissue pathology, and occlusal problems were ruled out. The patient demonstrated a canine guidance occlusion on the left side with minimal signs of nocturnal bruxism. A comprehensive clinical dental and periodontal assessment is necessary to rule out or identify all intraoral diseases, including mucogingival issues, dental caries or other restorative deficiencies, occlusal problems, periodontitis, hard or soft tissue, and periapical pathologies.
Imaging
Initially, a preoperative panoramic radiograph was taken to have a general overview of the maxillary sinuses with the adjacent dentition and bone structures. Panoramic radiographs could be used as preoperative imaging evaluation to plan maxillary implant rehabilitation. This technique is used to visualize the maxillary sinus and evaluate the remaining alveolar bone. However, panoramic radiographs have inherent limitations in the three-dimensional visualization of the anatomic structures and related pathologies.
A cone-beam computed tomography (CBCT) scan was ordered for the posterior right maxillary region to evaluate factors related to the maxillary sinus lift surgery (MSLS) surgery, including the patency of the ostium, the presence of septa in the antral cavity, vascularization, the status of the Schneiderian membrane, mediolateral distance of the sinus cavity, residual bone height and width, residual bone quality, lateral wall thickness, and ruling out any pathological conditions of the sinus.
The CBCT from the targeted site showed an inadequate vertical height of the remaining alveolar bone caused by sinus pneumatization; however, its width was adequate for placing regular implants. The lateral wall thickness was about 1 mm, and the residual bone quality was measured as D3. The antral cavity was devoid of sinus pathology, the ostium passage was clear, and the sinus membrane appeared thin. Septa were also not present in the antral cavity.
Labs
Unless explicitly required by the patient’s medical history, routine laboratory workup is not indicated before an MSLS or implant surgery.
Assessment
The patient demonstrated a unilaterally resorbed edentulous posterior maxilla caused by increased maxillary sinus pneumatization and inadequate alveolar bone beneath the sinus for implant placement.
Treatment
Maxillary sinus floor augmentation has become the most popular strategy among surgeons because of its predictability, low morbidity, and technical simplicity. Various methods can be used to augment the excessively pneumatized maxillary sinus to accommodate an implant of at least 10 mm in length. Sinus membrane elevation followed by implant placement without grafting also has its advocates. A lateral wall antrostomy, or window (open technique), is the most common technique used to expose the sinus floor. Alternatively, the Summer osteotome technique (closed technique) can be used for selected cases when less than 4 mm of sinus floor elevation is needed. The grafting material or materials are selected based on the surgeon’s preference. If a decision is made to use autogenous bone, the harvest technique planned must be explained to the patient so that informed consent can be obtained. The decision on simultaneous or staged augmentation and implant placement is made based on the quality and quantity of host bone at the surgical site.
There are four primary types of grafting material available for sinus augmentation:
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Autogenous bone
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Allogenic bone
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Alloplastic materials
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Xenogenic materials
These materials can be used alone or in combination (composite graft) for sinus augmentation. Autogenous bone (cancellous marrow or cortical shavings) is a popular and predictable material for sinus grafting. Donor sites for bone harvest include intraoral sites (maxillary tuberosity, zygomatic buttress, mandibular ramus, posterior body or symphysis) and extraoral sites (tibial plateau and anterior iliac crest are the most commonly used). Donor site selection is based on the clinical situation and the amount and type of bone needed. Intraoral sites must be considered a limited source of cancellous marrow but are a good source of surface-derived autogenous cortical bone (cortical shavings). Extraoral sites can provide sufficient autogenous cancellous marrow for large, bilateral augmentations. Some surgeons prefer to construct a composite graft by mixing autogenous bone with allogenic, alloplastic, or xenogenic graft materials, especially when inadequate autogenous bone is available.
Another alternative modality for maxillary sinus floor augmentation is the use of recombinant human bone morphogenetic protein 2 (rhBMP-2), which has been shown to induce de novo bone formation. rhBMP-2 in combination with a collagen sponge (Infuse, Medtronic) is placed on the sinus floor in a fashion similar to bone graft material; it acts as an osteoinductive factor that stimulates undifferentiated mesenchymal cells to transform into osteoprogenitor cells and produce bone. De novo bone formation for sinus augmentation and placement of functional implants has been shown to be predictable and comparable to that seen with autogenous bone grafting; however, recent reports of increased adverse events with this modality have been published.
For this patient, a fixed-type restoration of the posterior maxilla is planned using a simultaneous implant placement with MSLS via the lateral window approach was planned. The lateral method was selected instead of the transcrestal approach because the residual bone height was 4 mm or less in the planned surgical sites.
The patient was given a 0.2% chlorhexidine mouthwash to rinse his mouth before the surgery. This procedure can be done under local or intravenous sedation anesthesia. A midcrestal bevel horizontal incision was performed with a 15C blade on the keratinized tissue of the alveolar ridge 4 mm away from the estimated window design, which might allow for the simultaneous insertion of implants and MSLS. A vertical buccal incision was also done on the anterior side of the horizontal incision 10 mm away from the window outline as a releasing incision to improve the accessibility to the lateral sinus wall and ensure the presence of sufficient soft tissue over the bone. The reflection of a full-thickness buccal flap was performed to a position superior to the lateral window’s projected height. The flap needs to be reflected up to the zygomaticomaxillary buttress for the surgeon to have complete access to and visualize the lateral sinus wall. Primary closure can be easily performed using this flap design. While elevating a full-thickness flap, the elevator must adhere to the bone surface to keep the periosteum unchanged.
The osteotomy stage commenced after the flap was raised to the intended elevation. Because the lateral wall of the sinus was 1 mm thick, the complete osteotomy technique was planned for creating the lateral window. A small round tungsten carbide surgical bur (no. 4) was first used to create an oval outline. The crestal border of the outline was 3 mm apical to the sinus floor to make a reservoir to contain the graft material. The coronal edge of the outline was created 10 mm apical to the crestal border, measured based on the length of the planned implants and the height of the graft. The mesial border was located just distal to the canine tooth, and the distal edge was placed on the imagined distal surface of the missed tooth #16. Then the remaining bony island was scraped away to a paper-thin bone lamella until the bluish color of the mucosal membrane was apparent beneath it ( Fig. 34.1 A). The sharp edges of the window were smoothed with a larger round diamond bur to avoid membrane perforation. The lateral bony window can be removed and discarded, crushed to make bone chips, or returned to its original position after the completion of the surgery (bone lid). It can also be scraped (complete antrostomy) or left intact and rotated inwardly and upwardly (top-hinge trapdoor technique). However, the complete antrostomy procedure provides easier biomaterial grafting and better control of the sinus membrane’s structural integrity, minimizing intra- and postoperative adverse events. Then membrane elevation was started at the edges using a short blunt curette. When at least 2 mm of membrane detachment was achieved along all borders, the elevation gradually progressed from the superior aspect of the osteotomy, proceeding 2 to 3 mm mesially toward the mesiosuperior line angle. Finally, longer angled curettes were used to passively make more elevation in all directions, making the membrane free in the cavity, especially from the medial sinus wall, to provide a good blood supply for the bone material to regenerate. In this way, the membrane was elevated coronally ( Fig. 34.1 B) and to a level higher than the upper border of the window to provide adequate space for a pressureless biomaterial placement. To reduce membrane perforation, it is crucial to remember that surgical curettes should always be in close touch with the underlying bony walls.
When the patient was asked to breathe in and out to evaluate the degree of the membrane release, a large perforation was observed in the central part of the membrane. This was expected anteriorly because the Schneiderian membrane was of a thin biotype, diagnosed earlier on CBCT and confirmed visually at the time of the surgery. Because the elevation of the membrane was nearly completed, no more attempts were made, and neither was allowed to elevate the membrane. The perforation’s size was 7 × 7 mm ( Fig. 34.2 ), which is considered a large perforation. Bioresorbable collagen membranes, autologous fibrin glue, demineralized freeze-dried human lamellar bone sheets, oxidized regenerated cellulose, sutures, and platelet-rich fibrin (PRF) can all be used to repair Schneiderian membrane perforations. The surgeon preferred the collagen membrane method. Two large (15 × 20 mm) resorbable membranes of the freeze-dried bovine pericardium (Tutopatch, Tutogen GmbH) were first soaked in a sterile saline solution for 5 minutes and then positioned on the perforated membrane near each other ( Figs. 34.3 and 34.4 ), covering beyond the margins of the perforation ( Fig. 34.1 C). Because an effective seal was developed and the height of the residual alveolar ridge was sufficient to provide adequate primary stability for the planned implants, it was decided to insert implants simultaneously with the bone graft materials. As a result, the osteotomy was prepared using drills following the manufacturer’s instructions. Before the implants were inserted in the prepared sites, the sinus cavity was partially grafted by a xenograft material (bovine bone granules; cerabone, 1.0–2.0 mm, Botiss Dental) soaked in a sterile saline solution at the medial sinus wall with the help of a bone carrier instrument. Afterward, implants (Neobiotech) were inserted according to the manufacturer’s protocol 0.5 mm subcrestally ( Fig. 34.5 ) with the implants’ tips exposed in the created compartment in the maxillary sinus ( Fig. 34.1 D), and a torque wrench was used to measure their primary stability (25 Ncm). Then the rest of the biomaterial was densely packed around the exposed implants with a condenser to facilitate de novo bone formation ( Fig. 34.1 E). Overpacking was avoided because it prevents vascularization and may cause necrosis of the biomaterials.
At the end of the surgery, the antrostomy was covered by directly suturing the mucoperiosteal flap over the grafting material. For flap closure, the margins of the flaps were first passively approximated; single interrupted sutures were used for the releasing incision; then continuous lock sutures were placed on top of the crestal ridge ( Fig. 34.6 ). The suture was 3/0 resorbable polyglycolic acid. An immediate postoperative panoramic image was taken to see the surgery results, including the position and angle of the implants and the success of repairing the perforation. It was observed that the bone graft material was not pushed into the antral cavity; otherwise, if there were an appearance of bony granules scattered in the sinus cavity, it would be the result of an unsuccessful perforation repair. In addition, a confined dome-shaped radiopaque appearance from the presence of the bone material in the sinus cavity confirmed success. The implants also were in a proper position and angulation for further prosthetic rehabilitation ( Fig. 34.7 ). Then postoperative instructions were given to the patient verbally and in writing, including not blowing his nose; not sneezing with his mouth closed; no swimming, scuba diving, or flying in pressured aircraft; no heavy lifting of weights; and no playing a musical instrument that requires blowing for 1 week. In addition, postoperative medications were prescribed for him, including a nonsteroidal antiinflammatory drugs (ibuprofen 400 mg every 6 to 8 hours for 3 days), painkiller (paracetamol 500 mg orally, every 4 to 6 hours for 3 days or the shortest duration possible), antibiotics (amoxicillin–clavulanic acid 625 mg orally, every 8 hours for 7 days), decongestant (oxymetazoline HCl 0.05% nasal spray, every 10 to 12 hours for 3 days), and chlorhexidine 0.2% mouthwash (10 mL rinsed in the mouth for 1 minute and then spat out, every 8 to 12 hours for 5–10 days).
A postoperative follow-up was done for the first time 48 hours after the procedure, again at 14 days for removing sutures, and finally at 6 months for the next stage. However, the patient was advised to return immediately if there were any symptoms of bleeding, epistaxis, hematoma, the expulsion of graft debris through the nostrils, wound opening, infection (intraoral swelling, redness, fistulation, suppuration, tenderness, excruciating pain, swelling of the face, abscess, increased body temperature, or discharge of graft materials through the fistula), and sinusitis (nasal congestion, purulent secretion, and headaches). The patient did not have any complaint at any follow-up sessions on any of the earlier-mentioned symptoms, providing evidence that the surgery was untroublesome. Six months later, the patient returned for the prosthetic rehabilitation of the submerged implants. He was reevaluated clinically and radiographically at this session. The visual examination and the second CBCT confirmed no complications, full recovery of the tissues, and graft integration. The implant stability was ideal as assessed using the resonance frequency analysis technique by the Osstell device.
Complications
Complications may arise intra- or postoperatively. The former includes Schneiderian membrane perforation, bleeding, inadequacy in the primary stability, surgical complications, neurosensory damages, and implant dislodgement into the sinus. Postoperative complications include bleeding, graft leak, wound dehiscence, infections associated with MSLS (including surgical site or graft infection), and postoperative sinusitis. Typical postoperative manifestations include edema, ecchymosis, and mild to moderate pain that typically subsides within 3 weeks and is rarely spontaneous in the first few days. There may also be a slight nosebleed. The resolution of symptoms 3 weeks later points to a typical postoperative healing phase. Although acute spontaneous pain is typically absent, its presence should trigger an immediate investigation by the clinician. The management of sinus membrane perforation, its contributing variables, and prevention strategies make up a sizable portion of the discussion section. Additionally, Table 34.1 provides a summary of the factors to take into account for other adverse events.
| Intraoperative Complications | |||
|---|---|---|---|
| Contributing Factors | Prevention | Management | |
| Bleeding |
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| Inadequacy in the primary stability |
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| Damage to the infraorbital nerve and the superior alveolar nerve branches |
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The neurosensory changes (mild paresthesia, dysesthesia, or anesthesia) are primarily temporary and pass within 6 months |
| Implant dislodgement into the sinus |
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| Postoperative Complications | |||
| Bleeding |
|
|
|
| Hematoma |
|
Same as for bleeding |
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| Graft leakage |
|
|
|
| Wound dehiscence |
|
|
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| Surgical site or graft infection |
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|
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| Postoperative sinusitis |
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