Immediate functional loading of provisional implants in the reconstructed atrophic maxilla: preliminary results of a prospective study after 6 months of loading with a provisional bridge

Abstract

Implant-prosthetic rehabilitation of atrophic maxillae remains a challenging problem. The aim of this paper is to describe a novel treatment for functional rehabilitation of the atrophic maxilla and to discuss preliminary results of this treatment protocol. A prospective pilot study was carried out in 10 patients who underwent bony reconstruction of atrophic maxillae under general anaesthesia, with autologous calvarial bone grafts and simultaneous placement of six provisional implants. The provisional implants were loaded with a provisional acrylic bridge 1 day after surgery. After 6 months, the provisional implants were removed and final implants were placed under local anaesthesia, again in an immediate loading concept with a provisional bridge, followed by a final bridge after another 6 months of healing. The bone grafts integrated well in all 10 patients without infectious complications. The prosthetic survival of the provisional bridge at the time of placing the implants was 100%. All final implants could be placed and immediately loaded with a second provisional bridge. Patient satisfaction was high due to limited postoperative inconvenience and immediate fixed prosthetic rehabilitation. The preliminary results of this pilot study demonstrate that this treatment protocol is a well tolerated treatment for patients with maxillary atrophy desiring dental rehabilitation.

Alveolar bone loss is a common finding in periodontal disease and in edentulism. The retention of a removable prosthesis becomes arduous with progressive bone atrophy and accelerates bone loss. Implant treatment is difficult due to insufficient bone height and width for implant placement. Many non-grafting and bone-grafting implant protocols have been described, but implant treatment in severe maxillary bone atrophy remains a challenge.

Non-grafting solutions include placement of angulated implants, zygoma implants and more palatal placement of implants to obtain a prosthetic rehabilitation, but if non-removable implant-supported restorations are placed, the maxillomandibular relation can not be altered to compensate for the changes in facial form and appearance . Other solutions include guided bone regeneration, distraction osteogenesis, crestal split osteotomy and sinus floor elevation .

In cases of extensive grafting procedures, autologous bone remains the gold standard. Bony reconstruction with autologous bone grafting is considered time-consuming. After extensive reconstruction of the alveolar ridge, a healing period of 3–6 months is required before final implants can be placed. If no immediate loading protocol is followed, osseointegration takes another 4–6 months before prosthetic rehabilitation.

Autologous bone grafting from the anterior iliac crest is associated with postoperative morbidity (e.g. pain and gait disturbance due to muscle detachment). Since the amount of resorption of the grafted bone is variable and unpredictable, resorption is anticipated by overcompensating the volume during reconstruction. The use of calvarial bone has been described extensively. Its mechanical and biological superiority to iliac crest bone is well documented in the literature .

Regarding prosthetic rehabilitation, wearing a removable denture during the healing phase following bone grafting is problematic due to lack of retention. Resorption of the grafted bone also increases.

The purpose of this prospective pilot study is to present the preliminary results after immediate functional loading of provisional implants in the reconstructed atrophic maxilla.

Materials and methods

This prospective pilot study involved patients with moderate to extreme maxillary bone atrophy: class IV to VI according to C awood and H owell , caused by terminal periodontitis or edentulism. Ten consecutive patients were recruited from 2006 to 2009 and underwent identical surgical treatment protocols ( Table 1 ). Patients unable to quit smoking or with severe uncontrolled diabetes were excluded. All patients were treated by the same surgeon (CDC) and the same prosthodontist (LB).

Table 1
Treatment protocol.
First visit
Medical history
Sinus problems (if history: ENT)
Smoking
Clinical evaluation
Denture convertible?
Radiological evaluation
If not present CBCT
Explanation of operation and rehabilitation
Informed consent
Operation
General anaesthesia
Harvesting cranial bone, reconstruction donor site
Reconstruction maxillae
Placement of IPIs
Day (operation) + 1 day
Dismissal from hospital
Coupling of temporary IPI-supported fixed bridge (immediate loading of IPIs)
Day + 10 days
Check-up
Removal of skin staples (donor site)
Day + 6 months
Local anaesthesia
Removal of temporary fixed bridge
Removal of IPIs
Removal of osteosynthesis screws
Placement of implants
Coupling of temporary implant-supported fixed bridge (immediate loading of implants)
Day + 1 year
Removal of temporary implant-supported fixed bridge
Placement of final implant-supported fixed bridge

At the first consultation, patients were evaluated clinically and radiologically (by CDC and LB). If no radiological imaging was available, the patient received a cone-beam computed tomography (CBCT) dentascan (i-CAT, Imaging Sciences International, US), for evaluation of the maxillary atrophy ( Table 2 , Fig. 1 ). If maxillary sinus problems were encountered, the patient was evaluated by an ENT surgeon and, if necessary, treated.

Table 2
Patient information, dental status, maxillary atrophy.
Patient Initials Date of birth Age (years) o Sex Dental status Cawood Smoker Disease
1 VB A 28/01/1967 39 F 16, 17, 27 in situ IV Yes Eating disorder
2 C A-M 11/09/1954 52 F Fully VI No
3 V S 18/01/1959 47 F Fully IV No Allergy
4 V C 11/10/1961 46 F 17, 11, 21, 24, 26, 27 in situ ; terminal periodontitis IV No
5 T C 20/08/1948 59 F Fully V No
6 DM F 21/11/1948 59 M Fully V No GERD *
7 V K 26/06/1955 53 F Periimplantitis and implant loss, after earlier bone grafting $ VI No
8 DV G 30/08/1951 58 F Fully V No
9 L I 30/04/1954 56 F 17, 25 in situ V No Hepatitis A
10 V J 27/05/1949 60 F Fully VI No

o Age at enrolment/operation.

* GERD: gastro oesophageal reflux disease.

$ With iliac bone grafts, in another hospital.

Fig. 1
Screen capture of preoperative situation (iCATVision, i-CAT, Imaging Sciences International, USA), showing the extensive atrophy of the maxillae (note localised absence of alveolar process: yellow arrows).

Depending on the patients’ requirements and prosthetic factors, the existing denture in the maxilla was evaluated to determine if this prosthesis could be converted into the provisional bridge fixed to the provisional implants. The main prosthetic factor was the palatal stability of the prosthesis. If the prosthesis could not be stabilised on the upper jaw, a relining was performed first.

The existing prosthesis was transformed into a surgical template. A new prosthesis was created in case the existing denture could not be converted. The surgical template was used to indicate the ideal implantation locations of the temporary implants. The prosthesis was transformed into the surgical template by creating a palatal window in the prosthesis behind the teeth and the vestibular flanges were removed to allow seating of the prosthesis after the placement of the vestibular calvarial bone onlays. Informed consent was obtained from all patients.

First surgical phase

Figure 2 shows the clinical situation at the start of the operation. Autologous cranial bone graft reconstruction of the maxillae was carried out under general anaesthesia. After nasotracheal intubation, 2 g of amoxicillin-clavulanic acid and 125 mg methylprednisolone were administered intravenously.

Feb 5, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Immediate functional loading of provisional implants in the reconstructed atrophic maxilla: preliminary results of a prospective study after 6 months of loading with a provisional bridge
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