Vasileios Soumpasis, Stuart Kilner and Rajesh Vijayanarayanan discuss the treatment of a patient in need of extensive restoration in both arches.
Publication Credit: Published July 2016 in Implant Dentistry Today. An FMC Publication
CPD: Educational aims and objectives: The aim of this article is to present a case study showing the oral rehabilitation of a patient using implant-supported full arch bridgework.
Expected outcomes: Correctly answering the questions on page xx, worth one hour of verifiable CPD, will demonstrate that the reader understands the surgical protocols and rationales for the treatment approach used in this case.
A 38-year-old male patient presented at the clinic suffering from an inability to feed himself properly for the last 20 years and a lack of confidence in social situations due to the current status of his dentition. Additionally, he was suffering from recurrent abscesses that were adding to his already lowered quality of life. The patient had visited other clinics, all of which only gave him the option of complete dentures, and he was seeking an implant-supported solution.
The patient’s medical history was clear, apart from a smoking habit of 15 cigarettes per day. He was very anxious about dental treatment and had not had a dental appointment for the last 25 years. The last time the patient had visited his dentist, he had undergone extractions of his severely decayed maxillary and mandibular molars without suffcient anaesthesia, which had left him with a dental phobia.
As a teenager, his diet included a large amount of carbohydrates and a high intake of acidic foods. He had also neglected his oral hygiene in the intervening years. The patient was looking for a ‘return to normality’, through restoration of his masticatory function and aesthetic rehabilitation so that his appearance was appropriate for his age. As part of this return to normality, the patient expressed a desire to have fixed restorations.
Before any examination was carried out, the patient was informed that no treatment would be undertaken without him stopping smoking, as smoking makes healing problematic and treatment outcomes unpredictable. The patient agreed to this because it would also create a better environment for his young child.
A clinical and radiological examination was carried out to assess the patient’s suitability for rehabilitation with dental implants.
There was no obvious facial asymmetry, and the patient’s lymph nodes, TMJ and soft tissues all appeared normal. Screening for oral cancer was negative. The lateral profile view revealed the patient had a skeletal class I maxillomandibular relationship, taking under consideration he had no occluding teeth. The patient’s smile line was low.
The patient had suf cient mouth opening (50mm), his arch forms were elliptical and his gingival biotype was moderate to thick. On his upper jaw he had decayed retained roots from UL6 to UR6 and on his lower jaw from LL5 to LR5. His BPE score for all sextants was 2. Apart from caries, signs of erosive wear were also evident, supporting the tooth surface loss that lead to a total bite collapse and resulted in a signi cant decrease of the occlusal vertical dimension that was not compensated for by the alveolar bone.
The determination of the occlusal class could not be completed due to the severely decayed remaining dentition. In order to provide the patient with an accurate diagnosis and to evaluate bone levels and quality for potential implant placement a 3D CBCT scan was performed (Figure 3). The scan revealed the presence of large bone defects on the maxilla around the apices of the decayed roots, con rming the history of recurrent abscesses. Periapical lesions were also found on the mandible but these were not as extensive as those in the maxilla.
In the mandible, although the height of the alveolar bone was suf cient, its width and shape made implant placement challenging and potential sites were very speci c. Due to the large bone defects and destruction of the alveolar bone architecture, potential implant sites in the maxilla were again limited. Furthermore, the left sinus cavity appeared pneumatised.
The quality of the alveolar bone seemed adequate for implant placement, taking into consideration the Hounsfield unit measurements of the CBCT scan and observing its overall appearance. The pterygoid plates and their access through the maxillary tuberosity were also evaluated.
The patient was provided with the following diagnosis:
- Severe caries
- Generalised chronic plaque-induced gingivitis
- Severe generalised tooth surface loss due to erosion
- Acquired tooth loss due to caries
- Chronic AP with periapical lesions and recurrent abscesses in several sites in the oral cavity
- Loss of occlusal vertical dimension (OVD).
A plan was made for full mouth rehabilitation via a fixed full-arch implant- supported prosthesis for the upper and lower jaws.
The patient was not willing to undergo bone grafting, due to the high costs and unpredictability of the outcome, or zygomatic implants, again due to the expense. The classic All-On-4 treatment modality was not feasible due to insuf cient bone in the anterior maxilla. Therefore, should the pterygoid implants be unable to engage successfully in cortical bone, a complete upper denture would be offered to the patient.
The palatally-positioned implants would be placed into fresh extraction sites, with loading scheduled to take place seven days after the surgery. These protocols have been proven to have high success rates (Gokcen- Rohlig et al 2010; Penarrocha-Diago et al 2011; Soydan et al 2013) when followed by the fitting of full arch prostheses that involve splinting the implants through a rigid metal framework (Degidi 2009), and when the implants are placed with high primary stability through bicortical fixation.
Thorough degranulation of the extraction sockets and bone defects would be carried out before implant placement. An alveoplasty would also be done before and after placement in order to create an ideal platform around the implant heads, helping placement and facilitating future oral hygiene. The rehabilitation of the maxilla and mandible required the occlusal vertical dimension (OVD) to be increased in order to restore the aesthetics and allow for the bulk of the restorative materials used to fabricate the full arch implant-supported prostheses.
For that reason, wax rims on acrylic bases were made to be tted over the retained roots to properly record the jaw relationships. By positioning the length of the wax rim, the midline, smile line, canine line and parallelising the occlusal level with the inter- papillary line and camper plane – as would be done for complete dentures – we were able to assess the facial aesthetics and select appropriate teeth based on the patient’s facial characteristics. A relationship record was taken of the patient’s jaw in retruded axis position. A facebow was used to transfer the cast of maxillary dentition to a semi-adjustable articulator. The shade of the teeth was also decided at this stage.
Figure 3: A 3D CBCT scan was performed to evaluate bone level and quality
The lab put together a diagnostic wax- up on the rigid acrylic bases in order to reproduce the desired function and aesthetics.
A restoratively driven surgical plan was followed in order to place the optimum number of implants to eliminate cantilevers. Because of this, and given the condition of the alveolar bone, it was decided that ve implants would be placed in each jaw. The sites chosen for the maxilla can be seen in Figure 4.
Due to the patient’s previous traumatic experience, it was decided that oral sedation would be administered and the whole procedure would happen under local anaesthetic. Additionally, antibiotics and pre/postoperative non-steroidal anti- in ammatories (NSAIDs) were prescribed. The decision was made not to use corticosteroids to control any swelling, as the ef ciency of the surgical procedure and its completion in optimum time (an hour and a half for the maxilla and one hour for the mandible) was expected. The surgeon was highly experienced at performing under these strict conditions and as a result of his experience, ability and precision, guided surgery was not used.
Local anaesthetic was administered, after which the retained roots were extracted and a full-thickness mucoperiosteal ap was elevated. Thorough degranulation and irrigation with sterile saline solution followed. As planned, an alveoplasty was carried out before and after implant placement in order to create the platform that would later accommodate the full-arch pro le prosthetics.All implants in the maxilla were placed with a torque of 50Ncm in D3 (Misch classi cation) bone, apart from the pterygoids. that were torqued to 45 Ncm. In the mandible all implants were placed to a torque of 50Ncm. All multi-unit abutments were tightened to 35Ncm. A gingivoplasty was carried out after the multi-unit abutments had been placed in order to remove any excess soft tissue.
Before suturing the maxilla a rigid try-in was seated on the healing cups so the aesthetics of the maxillary dentition could be checked. A facebow recording was then taken to transfer the upper working cast to the semi-adjustable articulator. Implants were then placed in the mandible, with alveoplasty and gingivoplasty being carried out as in the upper jaw, and occlusal registration being taken before suturing. The desired OVD had been measured at an earlier appointment so a rigid acrylic base with wax rim was adjusted to t on the healing cups of the lower implants and an interocclusal registration record was taken in RAP at the desired OVD. After suturing, a plaster impression was taken for the mandible. On the day, it was decided to create a provisional upper full arch prosthesis that would be screwed on three implant abutments and be supported by all ve (Figure 5), by adjusting the rigid try-in with the insertion of restorative cylinder abutments and relining with PMMA in the clinic’s laboratory (rather than intraorally).
This approach was taken to boost the patient’s confidence, in light of his previous traumatic experiences, and to reassure him for the outcome of the treatment.
After the t of the maxillary provisional prosthesis an OPG radiograph (Figure 6) was taken to con rm full seating of the cylinders on the multi-unit abutments. The screws were torqued to 25 Ncm and a light body silicone material was used to fill the screw access holes. The patient was given his postoperative medication, reminded of his instructions, and sent home when the clinical team felt he could be dismissed.
The patient returned to the clinic seven days after implant placement for the t of his de nitive upper and lower xed full-arch prostheses, which had been fabricated in the clinic’s laboratory. On examination, and after removal of the maxillary provisional prosthesis, the soft tissues showed good healing and the patient didn’t complain of excessive pain, discomfort or swelling. No bruising was evident. One healing cup had loosened in the mandible, and the patient had removed it.
The fit of the cobalt chrome-PMMA pro le full-arch prosthesis followed. Because of the inherent rigidity of the plaster impression, and the high precision of the CAD/CAM milled metal framework, a passive fit was secured.The screws were tightened to 25Ncm and an OPG radiograph was taken (Figure 10) to ensure full seating of the prosthesis on the multi-unit abutments.
After full seating of the prosthesis was observed on the OPG, the screw access holes were lled with a silicone material. The patient’s occlusion, comfort, aesthetics and phonetics were evaluated and a soft food, slow-chewing protocol was advised to be followed for the next five months.
Review appointments were scheduled for four weeks, four months and six months after the surgery. Postoperative soft tissue healing and maxillary soft tissue shrinkage were evaluated at the four-week appointment. Because of the importance of avoiding micromovement of the implants, any reline of the maxillary prosthesis would not be made before four months had passed, though a slight lisp was noticeable at this time.
The patient’s adaptation to the new vertical dimension was already successful and pronunciation of the ‘F’, ‘V’ and ‘S’ sounds was perfect. The patient was very satisfied with the comfort of the prosthesisand already happy with the reduced bulk compared to the provisional one.
At the four month review, the the upper full arch prosthesis was relined and the phonetic seal was restored. The patient maintained very good oral hygiene but the self-cleansing design of the highly polished prosthetics helped secure a high level of hygiene. At the six month follow-up, the prosthesis was removed from the patient’s mouth in order to confirm osseointegration of the implants and another radiograph was taken. The patient was then signed off and his maintenance protocol initiated. He was instructed to attend the clinic for an examination every 12 months.
The patient’s satisfaction was at the highest level and the restoration of his masticatory function, facial and tooth aesthetics were very pleasing and life-changing. The absence of cantilevers (Francetti et al 2015), the self-cleansing surfaces of the prostheses, the appropriate spacing between implants, their anchorage in dense cortical/ basal bone and their splinting with a rigid metal framework seven days after placement (Degidi et al 2009), combined with a soft, slow-chewing diet for the first five months and the establishment of a mutually protected occlusal scheme were factors that secured a positive treatment outcome in the short term, but also reassure us for its mid- and long-term prognosis.
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