Full-mouth rehabilitation with implant-supported prostheses; Vol. 9, No. 5

Drs. Vasileios Soumpasis, Stuart Kilner, Rajesh Vijayanarayanan, and Paul Coulthard discuss the treatment of a patient in need of extensive restoration

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.

Educational aims and objectives
This article aims to present a case study illustrating full-mouth rehabilitation with
implant-supported prostheses.

Expected outcomes
Implant Practice US subscribers can answer the CE questions to earn 2 hours of CE from reading this article. Correctly answering the questions will demonstrate the reader can:

• Realize a possible treatment technique for a patient with dental phobia and issues related to dental treatment avoidance.
• See possible implant treatment for a patient with large bone defects and destruction of the alveolar bone architecture.
• Visualize a plan for full-mouth rehabilitation via a fixed full-arch implant-supported prosthesis for the upper and lower jaws.
• Identify various aspects of the surgical phase that affect implant placement success.
• View treatment planning and implementation for restoration of a patient’s masticatory function and facial and tooth esthetics.

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 past 25 years. The last time the patient had visited his dentist, he had undergone extractions of his severely decayed maxillary and mandibular molars without sufficient anesthesia, 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 esthetic 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.

Examination
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 sufficient mouth opening (50 mm), 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 leads to a total bite collapse and resulting in a significant 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, confirming 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 sufficient, its width and shape made implant placement challenging, and potential sites were very specific.

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 pneumatized.

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.

Diagnosis
The patient was provided with the following diagnosis:

• Severe caries
• Generalized chronic plaque-induced gingivitis
• Severe generalized 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)

Treatment planning
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 insufficient 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 7 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 esthetics 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 fitted over the retained roots to properly record the jaw relationships.

By positioning the length of the wax rim, the midline, smile line and canine line, and parallelizing the occlusal level with the interpapillary line and camper plane — as would be done for complete dentures — we were able to assess the facial esthetics 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 (RAP). 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.

The lab put together a diagnostic wax-up on the rigid acrylic bases in order to reproduce the desired function and esthetics.

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 five 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 anesthetic. Additionally, antibiotics and pre- and postoperative non-steroidal anti-inflammatories (NSAIDs) were prescribed.

The decision was made not to use corticosteroids to control any swelling, as the efficiency of the surgical procedure and its completion in optimum time (an hour and a half for the maxilla and 1 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.

Surgical phase
Local anesthetic was administered, after which the retained roots were extracted, and a full-thickness mucoperiosteal flap 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 profile prosthetics.

All implants in the maxilla were placed with a torque of 50 Ncm in D3 (Misch classification) bone, apart from the pterygoids that were torqued to 45 Ncm. In the mandible, all implants were placed to a torque of 50 Ncm. All multi-unit abutments were tightened to 35 Ncm.

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 esthetics 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 occlusal vertical dimension (OVD) had been measured at an earlier appointment, so a rigid acrylic base with a wax rim was adjusted to fit on the healing cups of the lower implants and an inter-occlusal registration record was taken in RAP at the desired OVD. After suturing, a plaster impression was taken for the mandible and the maxilla.

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 five (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 fit of the maxillary provisional prosthesis, an OPG radiograph (Figure 6) was taken to confirm full seating of the metal framework interfaces 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.

Definitive prostheses
The patient returned to the clinic 7 days after implant placement for the fit of his definitive upper and lower fixed 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 profile 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 25 Ncm, 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 filled with a silicone material. The patient’s occlusion, comfort, esthetics, and phonetics were evaluated and a soft food, slow-chewing protocol was advised to be followed for the next 5 months.

Review
Review appointments were scheduled for 4 weeks, 4 months, and 6 months after the surgery.

Postoperative soft tissue healing and maxillary soft tissue shrinkage were evaluated at the 4-week appointment. Because of the importance of avoiding micromovement of the implants, any reline of the maxillary prosthesis would not be made before 4 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 prosthesis and already happy with the reduced bulk compared to the provisional one.

At the 4-month review, 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 6-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 and facial and tooth esthetics 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 7 days after placement (Degidi, et al., 2009), combined with a soft, slow-chewing diet for the first 5 months, and the establishment of a mutually protected occlusal scheme were factors that secured a positive treatment outcome in the short term, but also reassured us for its mid- and long-term prognosis.