The original Bränemark protocol dictated that the initial phase of implant osseointegration should be at least 4-6 months before any prosthetic restoration is placed.1 However, technological advancements have resulted in modern dental implant protocols that provide the possibility to immediately load implants.2 Certain guidelines must be respected to reduce stress at the developing bone-to-implant interface and achieve osseointegration. Implants require primary stability of at least 45 Ncm insertion torque. Excessive micromotions exceeding 150 µm will prevent new bone formation and a noncalcified, collagenous poorly vascularized scar tissue will characterize the interface.3
There is an assumption that joining several implants together via a rigid construction will reduce micromotion then facilitate the healing process and the immediate loading especially when evaluating implant treatment in the maxilla.4,5
Furthermore, implant design and surface play an important role; a rough implant surface with deeper and more threads is recommended. (Tealdo et al., 2008 ; Pieri et al., 2009; Palattella et al., 2008). Kim compared clinical outcomes and stability following immediate loading of two types of tapered implants in posterior maxilla and mandible and concluded that whenever high primary stability is acquired, tapered implants with hybrid textured surfaces are predictable. In spite of the influence of implant design on marginal bone loss, all tapered implants showed successful clinical outcomes and stability in immediate loading.6 This concept has been used by many authors (Cannizzaro and Esposito, 2007) and is considered by many as a viable treatment modality for the rehabilitation of the edentulous jaw.7 Over the past decade, immediate restoration of full-arch dental implants in the mandible has become a clinically validated mode of therapy.8 Ledermann used an immediate loading protocol with 4-screw designed endosseous implants in the anterior mandible using a bar-retained overdenture and showed a success rate of 92.80%.9 The reported success of immediate loading in the mandible has encouraged the application of similar treatment in maxilla. However, a more limited degree of success in maxilla v/s the mandible has often been attributed to poorer bone density. Lekholm and Zarb described maxillary bone as more trabecular and softer in nature (also known as type 3 or type 4), while mandibular bone is more cancellous and denser (type 1 or type 2).10 This anatomic difference results in lower primary stability, greater micromotion, and greater likelihood of fibrous healing and failure of implants to osseointegrate in maxilla when implants are immediately loaded.11 Despite the risks of failure in maxilla, reports demonstrating its viability, reliability, and success can be readily found in the literature.5 Romanos (2009) used an immediate loading protocol and concluded that it can be used successfully in maxilla when implant primary stability and a soft diet for the initial stages of healing are considered to 8 weeks of healing.12 Vervaeke and co-workers treated patients with immediately loaded implants in the maxilla supporting fixed full dentures and found that immediate loading in the maxilla is a predictable and reliable treatment option with high survival rates and limited peri-implant bone loss after 2 years when using fluoride-modified implants.13
The purpose of the present clinical case report was to describe and discuss the rehabilitation of edentulous maxilla in a female patient with an implant-supported fixed restoration using an immediate loading protocol.
A 50-year old female consulted our clinic with defectuous restorations and remaining underlying roots. Most teeth were lost due to deep decay, periodontal pockets and furcation involvement. The patient had high esthetic and functional concerns. Extraoral examination revealed no asymmetry, no swellings, and no tender or palpable cervical or submandibular lymph nodes. Intraoral examination revealed residual decayed roots with deep periodontal pockets, bone resorption and mobility. Radiographic examination revealed bone resorption and furcation involvement in maxillary and mandibular teeth (Fig.1). Patient had a noncontributory medical history, she was a light smoker.
Initial Prosthetic Treatment
The patient desired implant-supported fixed prostheses and was qualified for an adequate treatment protocol. After clinical and radiographic examinations, the treatment planning included teeth extraction followed by immediately loaded implant prostheses in the maxilla and conventional delayed loading in the mandible. This clinical case illustrates surgical and fixed prosthetic implant-supported immediate loading protocol in the edentulous maxilla.
A maxillary immediate complete denture was fabricated. It was implemented in centric relation with respect to proper vertical dimension, esthetics and phonetics. It was converted later into a provisional fixed bridge over the implants.
Initial OPG revealed a resorbed alveolar bone with insufficient height in left and right posterior maxillary regions with maxillary sinus pneumatization (Fig.1). So sinus floor elevation was performed 9 months prior to implant placement.
The day of the intervention, after the application of local analgesia with 1:100,000 epinephrine, existing crowns were removed and remaining roots (#13, #12, #11, #21, #24) were extracted (Fig.3). A crestal incision was performed in edentulous ridges to place implants (Zimmer, ScrewVent). Mucoperiosteal flap was raised, and alveolar ridge was exposed. 8 implants were placed in maxilla: 5 implants were placed in healed bone ( in areas #16, #15, #14,#26,#27) and 3 others were immediately placed in fresh extraction sockets (in areas #12, #23, #24) (Fig.4). When the latter fixtures were placed, the space between the vestibular cortex and implant surface was filled with bone substitute (Puros), and a connective tissue graft taken from the palate was used to thicken soft tissues in anterior maxillary region (Fig.5). Implants were placed with a preset insertion torque of 35 to 45Ncm. Implant length ranged from 10 to 13mm and implant diameters were 4.1 and 4.5mm.
Temporary abutments were screwed on the top of each maxillary implant to support the provisional fixed restoration. Mucoperiosteal flaps were finally sutured with 4.0 suturing resorbable material (Vicryl) (Fig.6).
The maxillary denture was perforated according to the emergence of these temporary abutments. The pink acrylic resin was removed to convert the denture into a provisional bridge. (Fig.7)
Cotton pellets covered the provisional abutment screws and the maxillary denture was filled completely with autopolymerizing acrylic resin (Alike, GC-FUJI- USA). The resin was allowed to fully polymerize on temporary abutments. The patient was instructed to close in centric relation and correct vertical dimension was achieved. After acrylic polymerization, abutments were unscrewed and the entire provisional device (acrylic provisional incorporating the 8 provisional abutments) was removed in one piece. Provisional restoration was trimmed, and polished for optimal strength and cleansability (Fig.8). The provisional was then screwed on top of implants and abutment screws were covered with a cotton pellet and the access holes were covered with composite. Occlusion was tested in static position and in all excursive movements; minor adjustments were made. The provisional prosthesis had flat cusps to minimize lateral forces14 and distribute them over a large area.15
It was made in immediate functional loading with bilateral simultaneous anterior and posterior occlusal contact to distribute the load over a large area16 Only centric markings were kept; in fact, there is a general disagreement on when and how to provide occlusal contacts but all authors agree to adjust the occlusion intraorally and eliminate interferences when performing lateral movements keeping only the centric contacts.16
Soft/liquid diet was advised for the first 4 to 6 weeks. Rinsing of the oral cavity with chlorhexidine digluconate 0.2% solution (Zordyl) was necessary. Postoperatively Augmentin 625 mg was prescribed 3 times a day for one week. Ten days after surgery, sutures were removed.
3 weeks after surgery, teeth extraction followed by implants placement was performed in the mandible as it was previously decided in the treatment planning. An acrylic provisional denture was inserted in the mandible, respecting the vertical dimension and the centric relation. This denture was going to be replaced after the healing period of 3 months by a fixed ceramo-metallic restoration. However, due to recent and unexpected personal considerations, the patient decided to postpone the prosthetic final rehabilitation in the mandible keeping the acrylic denture in place.
Final Restoration Procedure
After a conventional healing period, a final impression was made using Impregum impression material (Espe, Co. Germany). Determination of the correct vertical dimension of occlusion for edentulous patients is one of the most important steps in making dentures with adequate esthetics and function.17
Many techniques have been used for measurement of the vertical dimension of occlusion in edentulous patients.18 These range from using of preextration records (Wright, 1939) to the use of swallowing (Shanahan, 1956), functionally acquired jaw positions associated with phonetics (Pound, 1962) and cephalometric radiographs (Ellinger, 1968). Furthermore, many studies recommend a freeway space range of 2-4mm (Fenn, Liddelow and Gimson, 1961; Mitchell and Mitchell, 1995). Tyson and McCord stated that freeway space could be increased above this range for elderly patients and patients with atrophic mucosa overlying the residual ridge.19 In the present case report, an accurate assessment of the amount of freeway space was made; 3 mm were considered sufficient to provide comfort during function and speech. Given that the provisional restoration could be screwed on top of implants, the centric relation recorded in the correct vertical dimension was transferred by simply screwing the provisional bridge on top of implant analogs that were included in the final cast, without the need of registering centric relation with wax interocclusal rims.
Final casts were mounted on articulator in the correct centric relation and vertical dimension and artificial teeth setting was prepared for maxillary arch with respect to the scientific published guidelines. (Fig.10)
In fact, the anterior and posterior determinants of occlusion give two necessary parts of the successful occlusal scheme- support and guidance.20 Balanced occlusion was followed to establish harmonious contact between the working and balancing cusps. In establishing the height of the balancing cusps, any contact beyond the length of the working cusp was considered as interference. Contacts were made simultaneous on both the working and balancing cusps from centric occlusion to the end of the stroke. On another hand, Zinner et al. proposed use of guidelines to test anterior contours recommending that the maxillary anterior incisal edges follow the contour of the lower lip, the “smile line”, and all 6 maxillary anterior teeth should be in contact with their antagonists in maximum intercuspation. Evaluation of labiodental (“F” and “V”) and sibilant (“S” and “CH”) sounds are useful methods of ascertaining the lengths of maxillary incisors.21
Once esthetics and phonetics were satisfying, a silicone index of the artificial teeth setting was made and the record was sent to the laboratory. Definitive abutments were screwed on implants and the laboratory returned maxillary full arch framework for try in. X-Rays were taken to assure an adequate fit of the metallic copings.
Final ceramo-metallic restorations were then delivered and cemented with temporary cement (Temp bond; Kerr, Co., Karlsruhe, Germany) and patient was allowed to chew.
Occlusion was carefully checked in all excursive movements. Patient was re-evaluated once every 3 months for professional oral hygiene control. The clinical as well as radiological examinations showed an optimal soft tissue condition (Fig.11-12). No pain or infection or bone loss was observed during the entire 2 years observation period.
An increasing concern regarding the possibility to shorten the healing time period in the implant-prosthetic rehabilitation has become evident. Clinical studies (Calandriello et al., 2003; Glauser et al., 2005; Lindeboom et al., 2006; Donati et al., 2008; Esposito et al., 2009; Romanos et al., 2010) demonstrated that immediate functional loading implants placed with conventional installation technique and with sufficient primary stability may be considered a valid treatment alternative.22 Recent recommendations indicate that torque values at the time of placement should be greater than 32 N-cm.23 Quantity and quality of bone at the implant site also affect primary stability. When compared with bone from the mandible, maxillary bone can be particularly challenging for immediate implant placement because it has lesser bone density, a thin cortical plate, and proximity to the maxillary sinus.24 Implant designs that include threads and roughened surfaces significantly contribute to primary stability.5 Many studies have focused on the number of implants required for the immediate loading with a fixed prosthesis in the edentulous maxilla. Jaffin & kumar reported a 93% success rate when the number of implants placed is from 6 to 8.25 Capelli & Zuffetti showed a success rate of 97.5% when 4 to 6 implants were placed.26 Agliardi &Panigatti showed a 98.36% success rate when 2 axial and 2 tilted implants were placed.27 In fact, the number of implants needed when restoring cases with fixed prosthesis in the maxilla is greater than the number of implants needed to restore a fixed prosthesis in the mandible. At least 4 implants are needed in the anterior mandible to support a fixed prosthesis and a greater number of implants is necessary in the maxilla with a good bone quality and high primary stability.28,29,30
The present case report describes the treatment protocol in a patient using immediately loaded implants for full arch fixed restoration in maxilla. The patient experienced the virtues of implant therapy from the very beginning of treatment without having to endure a relieved and relined provisional removable denture.
The treatment protocol was based on the surgical and prosthetic guidelines presented in earlier reports.12,5,31 Surgery was atraumatic; Understanding the quality and type of bone and preserving that bone via atraumatic extractions are necessary for promoting successful osseointegration when loading implants immediately.32 Micromotions were minimal, in fact although early reports indicated that osseointegration could succeed with micromovements up to 500 µm currently accepted levels of micromovement ranging between 50 and 150 µm are known to produce no detriment to osseointegration.5 Insertion torque was greater than 45 N-cm for all implants. The patient’s absence of any systemic diseases or specific medications intake were also encouraging. Appropriate imaging investigation (CBCT) was used for calculations of bone mineral density prior to the implant placement and showed that the patient had an acceptable quantity and quality of alveolar bone. The patient’s preference for a fixed restoration during the entire treatment time was also taken into consideration. This case report showed new bone formation at the interface of immediately loaded implants without fibrous encapsulation or implant loss. (Fig.9- 12)
The provisional prosthesis was not removed at any time during the early period of osseointegration. Tarnow and co-workers showed that this procedure is advantageous regarding success of immediate, full-arch loading treatments.33
A screw-retained temporary restoration obviated the need for cement and the possibility of early de-cementation and biologic complications related to submucosal presence of cement. There is an increasing awareness among clinicians that undetected cement might be the cause of delayed peri-implant bone loss, occurring many years after delivery of the restorations (Wilson, 2009). A multicenter 3-year prospective study reported that peri-implant soft tissues responded more favorably to screw retained crowns when compared with cement retained crowns (Weber et al., 2006).
Restoring edentulous maxilla with a complete denture, a fixed implant-supported restoration or a removable overdenture is a complex and challenging procedure. All of these designs have been tested for safety, efficacy, and effectiveness in clinical studies.34 However, prosthesis design in edentulous maxilla should not be selected randomly or just on the basis of the patient’s or the practitioner’s preference. Rather, specific clinical parameters should be evaluated indicating whether a fixed or a removable implant-supported prosthesis or simply a conventional complete denture is preferable.35 These clinical factors are mostly related to bone and/or soft tissue deficiencies. The resorptive process can cause pseudo-prognathism, deficient facial support, speech disruption, and/or esthetic problems. The smile line and length of upper lip should also be considered in deciding on the appropriate prosthesis design as it may influence a patient’s satisfaction with the treatment outcome.36
In the literature, patients’ perceptions of maxillary implant treatment have been reported. Chan and co-workers treated patients with an atrophic maxilla with implant-supported overdenture prostheses after pretreatment with bone augmentation and staged implant placement and reported improvements in patients’ assessments of comfort, appearance, mastication, and speech.34 Lundqvist and Carlsson restored patients with maxillary hybrid fixed prostheses screwed on standard abutments, and 19 of 21 patients thought that their self-confidence had improved after treatment.37 Jemt and associates showed that implant treatment in the edentulous upper jaw functions well in a 15-year time perspective.38
While most of the reviewed studies reported improved quality of life after treatment with implant-stabilised restorations, other studies did not find significant differences in the general quality of life between these patients and those restored with conventional complete dentures. Studies have proved that the great majority of completely edentulous patients are satisfied with their complete dentures.39 Patients with low level education and those with better self-perception of their affective status and quality of life were highly satisfied in general with the aesthetic appearance of their complete denture. The quality of dentures showed the strongest correlation with patient satisfaction;40 the satisfactory arrangement of the artificial denture teeth and their appearance during function and speech, as well as the satisfactory adaptation of the dentures to the denture bearing area and the excellent retention reached during denture fabrication are sufficient for a good satisfaction.39 In addition to this, patients may resist implant supported restorations due to barriers, including cost, fear, and lengthy treatment times.41
In the present case report, the treatment selection was based on a thorough examination and diagnosis of specific scientific criteria to prevent any disappointing results
The extra-oral examination revealed a convex profile with no need for facial or lip support and a relatively low smile line. The intra-oral examination showed a Class I Angle, a keratinized mucosa with an absence of advanced resorption anteriorly and a minimal vertical resorption leading to optimal length of the clinical crown if the fixed design was adopted.
The examination of these data combined with the evaluation of the patient’s preference justified the adoption of the implant-supported fixed restoration as a final treatment option.
In conclusion, although maxillary immediate loading with fixed implant-supported restorations has yet to prove itself in long-term evidence-based studies, results of current various investigations suggest that by carefully following guidelines and respecting anatomical limitations of maxilla and the biology of alveolar bone, clinicians may achieve long-term success rates similar to those consistently realized in the mandible.
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by Dr. Rola Mortada, Dr. Mohammad Al Bazzal, Dr. Ibrahim Mortada, Dr. Khaldoun Rifai