The rate of infection in our group was relatively low – 4.3 %. However, the clinical management of the infections following this surgical procedure is very traumatic for the patient, requiring, besides antibiotic therapy, the surgical removal of the grafting material, the infected sinus mucosa and, in some cases, the implants placed adjacent to the graft.
Of the 116 patients included in the study, acute maxillary sinusitis occurred in the following patients (chronologically):
The first infection occurred in a 53 year-old female patient, who had grade 2 obesity, hypercholesterolemia, and generalized periodontal disease. We performed a lateral approach sinus bone grafting using xenograft, with concomitant placement of three dental implants in the positions of the second premolar, first molar and second molar. There were no intraoperative incidents. After two months the patient returned accusing cacosmia, headaches, pulsating pain in the canine fossa region and unilateral congestive rhinitis. Objectively, the patient presented a fistula in the first molar region, vestibular tumefaction in the premolar and molar regions, skin erythema and unilateral nasogenian tumefaction. The grafting material was removed together with the implants, with concomitant partial removal of the sinus membrane and closure of the oroantral communication with a buccal mucoperiosteal flap. We prescribed antibiotics, anti-inflammatories and nasal decongestants.
The second infection occurred in a 27 year-old healthy male patient, who underwent a sinus lift procedure with a xenograft and allograft mix and the placement of a dental implant in the second molar position. During the surgery a sinus membrane perforation occurred, 7–8 mm long, which was closed with a collagen membrane. After three weeks the patient returned, accusing a mild pulsating pain in the molar region. Upon inspection we identified a vestibular abscess in the molar region, and we performed a second surgical intervention consisting of incision and drainage of the abscess and the removal of the grafting material. The dental implant was left in place, and we continued with daily lavage with metronidazole and iodine solution for two weeks, with favourable evolution.
The third incident occurred in a 45 year-old female patient, heavy smoker (more than 20 cigarettes per day), with chronic hepatitis C virus infection and chronic obstructive pulmonary disease. Six weeks after the sinus lift surgery with alloplastic grafting material and simultaneous implant placement in the positions of teeth 2.5, 2.6 and 2.7 (#13, #14 and #15), the patient returned with odontalgia radiating in the zygomatic and periorbitary regions. We removed the grafting material together with parts of the Schneiderian membrane and two dental implants, we closed the oroantral communication and we prescribed antibiotics and anti-inflammatories (Fig. 2).
The fourth maxillary sinus infection was reported in an otherwise healthy 34 year-old female patient, 5 weeks after the uneventful placement of two dental implants replacing the missing second premolar and first molar with simultaneous lateral approach sinus lift and bone grafting with a xenograft material. The patient complained of unilateral hemicrania, and presented tumefaction of the gingival mucosa in the upper molar region and unilateral rhinitis. We removed the grafting material, we performed lavages with metronidazole and we prescribed antibiotics and anti-inflammatories, managing to maintain the two dental implants.
The last infection in our study group occurred in a 48 year-old male patient, heavy smoker (20–30 cigarettes per day), known with dyslipidemia and arterial hypertension. We performed a lateral approach sinus lift using a xenograft biomaterial and we placed two dental implants in the positions of teeth 1.6 and 1.7 (#2 and #3). There were no intraoperative incidents. Three weeks later the patient accused pain radiating in the zygomatic and periorbitary areas and congestive rhinitis. The patient presented genian and vestibular tumefaction, and we decided to remove the grafting material and the dental implants together with the infected sinus mucosa, we performed lavages with metronidazole and iodine and we prescribed antibiotics and anti-inflammatories.
All five patients recovered well after the second surgical intervention, with the remission of all symptomatology in 5 to 7 days, and normal sinus function and drainage were restored.
A PubMed search using the keywords “sinus lift” provides more than 700 results. However, adding the keyword “infection” to the previous search query narrows the results to 51. Out of these, less than half are clinical studies which discuss the complication rate of this surgical procedure. To our knowledge, there is only one other study [11] focused on evaluating the late complication rate of the sinus lift procedure, rather than the success rate of dental implants inserted in augmented sites, but it discusses both the immediate and the delayed implant insertion after the bone graft. Our results are similar to those of Vazquez et al. [11], with infectious complications in 5 out of 116 patients in our study and 9 out of 200 in theirs. This might suggest that whenever the bone volume is enough to confer a good primary stability of the implant, placing the implants at the same time with the sinus bone grafting procedure doesn’t affect the chances of success.
Our results are also in concordance with those of Ferri et al. [12], who report an infection rate of 3.5 %, but are lower than those of Khanberg et al. [13], who report signs of infection in 8 out of 36 patients, and higher than those of Kasabah et al. [14], who did not have any bone graft infection of maxillary sinuses in 146 sinus lift surgical procedures performed on 118 patients.
The abundant existing literature data on the subantral bone augmentation procedure has established it is a very safe procedure, with predictable results and a low complication rate. But as low as this complication rate may be, as we have shown in the beginning of this section, the clinical management of the complications is very difficult for the patient, with important pain and discomfort, prolonged overall treatment time and many treatment visits. The low complication rate also impacts the statistical value of this type of studies, since it is very difficult to find a statistically significant correlation between different clinical and paraclinical variables, in order to make a prediction on the chances of the occurrence of these complications. We did find a statistically significant difference when we compared the bone grafting materials used and the occurrence of the sinus infection (Table 2), but the results may be biased by the fact that we only used in three patients alloplastic bone grafting materials, and one of them developed acute maxillary sinusitis. In order to test this hypothesis, data from larger groups of patients are needed. An interesting study [15] reports a 0 % rate of infectious complications and a 100 % survival rate after two years when the implants are placed in the elevated sinus without any additional grafting material. However, the sample rate of this study [15] was low, evaluating only 47 implants inserted in 33 patients, so more studies are needed to confirm these findings.
There was no statistically significant correlation with the age of the patients, and no correlation with the smoking/non-smoking status, in accordance with the results of Levin et al. [16]. We found no correlation with intraoperative incidents like Schneiderian mucosa perforation, in accordance with another study [14], but a recent article [7] reports that graft failure was statistically higher in sinuses in which the membrane was perforated during the intervention. Also, another recent study [17] showed that certain factors such as a low albumin serum level and a prolonged intervention may constitute risk factors for complications after different oral surgeries.
A recent trend in oral rehabilitation using dental implants advocates the use of short implants, in order to avoid extensive surgical procedures like the lateral approach sinus lift [18–20]. Other studies [21] propose simplified techniques for the crestal approach sinus lift, for the same reason. Promising as these results may be, they still need to pass the trial of time, in order to replace the current standard of care in restoring the atrophic posterior maxilla.
