Dr Anita Gala Doshi, Dr Vivek Gaur, Dr Janani Iyer
Private Dental Practice, Prosthodontist,
Mumbai, Maharashtra, India
Private Dental Practice,
Etah, Uttar Pradesh, India
Department of Prosthodontics,
MGM dental college and hospital, Navi Mumbai, Maharashtra, India
Conventional implants require osseointegration to be successful, and often this process takes nearly 2-4 months. If this process is interrupted, it delays the restorative procedures. These implants have further complications, such as peri-implantitis due to their rough surfaces. Moreover, placing conventional implants into the atrophic maxilla or mandible requires prior extensive grafting procedures and sometimes even a sinus lift procedure that can severely contribute to increased appointments, chances of failures and treatment costs. The technology of Cortico-basal implantology was developed to overcome these limitations, The Cortico-basal Implant works with the bone differently compared to the conventional root-form implants. It follows the principles of orthopedic surgery and traumatology. They also do not require integration into the cancellous bone and are placed directly into the 2nd and 3rd (distant) cortical bone. Presented here is a case report of a 65- year- old female where a new and unique smooth- surfaced single-piece cortico-basal implants (with multiunit abutment) were placed. This enabled us to complete the restoration process within 72 hours using immediate functional loading protocol. These implants were loaded with definitive screw- retained prosthesis.
Keywords : Cortico-basal implant; Immediate functional loading; Single- Piece Dental Implants; Cortical Implantology; Multi-Unit Abutment
Citations : Doshi A, Gaur V, Iyer J. Immediate Functional Loading of Completely Edentulous Arches with a Screw Retained Definitive Prosthesis on Corticobasal Implants: A Case Report. J Prosthodont Dent Mater 2020;1(1& 2): 74-81.
Current advances in the field of implantology involve aiming to reduce the number of appointments as well as to simplify dental treatment procedures to increase patient acceptance and to decrease the risk of complications.This is achieved through immediate loading of dental implants. Immediate functional loading of oral implants is defined as a situation where the superstructure is attached to the implants at the time of the surgery or until no more than 72 hours post-surgery and brought in to chewing function. Immediate loading is desirable if the survival rate of the implant, as well as the outcome of the treatment, is in accordance with that of conventional loading.
Currently, two approaches towards the immediate loading of dental implants exist. The first approach is based on the compression screw principle, where the implant compresses the bone while being inserted into the undersized osteotomy.Lateral condensation of spongy bone is the guiding principle of these implants; Implant stability is significantly increased by a mechanism that could be regarded as “corticalization” of the spongy bone. The latter approach involves achieving cortical anchorage of strong and thin body screw implants, cortico-basal Implants, or basal implants. They are placed into the bone in such a way that the apical load transmitting threads of the implants are positioned (fixated) directly into the cortical plate distant (opposite) to the oral cavity.
The basal bone is present throughout our life and is resistant to resorption in the mandible and maxilla formed by macro trajectories. It is very solid, firm and forms the stress-bearing part of our skeleton. Implants anchored in this bone, can be loaded (splinted) with fixed tooth restorations immediately. One of the greatest challenges of restoring missing teeth in the posterior maxilla is due to the jaw bone resorption that results in deterioration in the quality of the bone post-extraction, thus impeding the process of implant placement in that region. To overcome this, the technology of Cortico-basal implants is used since; their load transmitting threads are anchored into the native, residual, cortical bone areas. The Cortico-basal implants not only avoids any additional surgical procedures but also provides a reliable anchor in cortical bone. This is very helpful even in severely reduced vertical bone heights, and it can (actually must) be loaded immediately without any waiting period. The cortical bone provides excellent retention for these implants. Dental implants anchored in this bone, can be loaded (actually splinted) with fixed restorations and brought to function immediately.
This paper presents a clinical case for immediate implant loading with a smooth surfaced single-piece Corticobasal implants (BCES and BCS, Simpladent) with multiunit abutments (BECES® MU) to restore fully edentulous maxillary and mandibular arches with a definitive screw-retained prosthesis within 72 hours. The protocol is to place six corticobasal implants in the anterior maxilla engaging into the nasal cortical floor and two corticobasal implants in the posterior maxilla bilaterally engaging the tuberoterygoid region. In the mandible, it is recommended to use four single-piece corticobasal implants in the anterior region engaging the lower border (base) of mandible between the mental foramina and two single-piece corticobasal implants in the distal part of the mandible on both sides engaging the lingual/vestibular cortical plate.
A 65-year-old, healthy female patient with completely edentulous maxillary and mandibular arches presented to the clinic with a chief complaint of missing teeth in the upper and lower jaw. She expressed a desire to have her missing teeth replaced with a fixed restorative option. The clinical examination (Figure 1) showed complete edentulous mandibular and maxillary arches. Radiographic examination (Figure 2) revealed an atrophic both arches. After discussing the various treatment options with the patients, such as removable complete dentures or implant supported prosthesis, it was to use a single-piece immediate loading smooth surface corticobasal implants with multi-unit abutment with screw- retained prosthesis. Upon obtaining the informed consent of the patient, local anesthesia (lidocaine 2% with adrenaline 1:100000) was infiltrated. The surgical procedure was performed as per the protocol.14 Following soft tissue cleaning with antiseptic 5% Betadine solution (water-based), a flapless preparation of osteotomy sites was carried out using the sequential order of calibrated drills recommended by the manufacturer, cooled with saline solution in external mode at a speed of 27000 rpm.
The implant beds were prepared with the use of a 2.0 mm drill (30 mm long). In the maxilla, two Pterygoid implants of 3.6mm diameter and 23mm and 26mm length were placed on each side. In the anterior region, one implant 5.5mm in diameter and 14mm in length was placed on each side on the lateral wall of the nose and two implants of 3.6mm diameter and 17mm length on both sides engaging the floor of the nose. For the distal mandible, a straight handpiece and for the anterior implants, an angled handpiece 1:1 (blue) was used to place implants. Two one-piece implants with a diameter of 3.6 mm and a length of 14 mm were placed with help of an insertion tool (Figure 5) and were anchored into the lingual cortical plate on both sides, where superior primary stability was achievable. Four Implants with a length of 23 mm were placed, and anchored in the base of the mandible in the inter-foramina region. The implants were bent to a favorable position of the internal thread with an angulation adapter (Figures 4, 5 and 6) so that the screw access holes faced occlusally (Figures 7, 8 and 9). Immediate post-surgery, the final impressions were made.
Open tray multi-unit impression copings were placed onto the BECES® MU implants, which were then splinted with a low shrinkage self-polymerizing resin. This ensured an accurate transfer without accidental displacement of the impression copings. An open tray impression was made with a rigid polyvinyl siloxane material to capture the positions of the implants and the soft tissues. following this, jaw relation was recorded. A metal framework of Co-Cr-Alloy was fabricated, and tried on the next day of implant placement (Figure 10). The bite, the vertical and the sagittal relationship as well as the aesthetic appearance, were checked at this stage. Definitive metal fused to ceramic prosthesis was screwed in onto the implants day after that is within 72 hours of implant placement. It was possible to give screw-retained restoration with the advantage of retrievability due to the use implants with MU abutments. The final tightening of all screws was done at 25N torque with each implant. (Figure 12, 13). Access holes were blocked with Teflon and filled with composite resin (Figure 14, 15). Treatment was completed with high patient satisfaction (Figure 16, 17).
Following the principles of corticobasal implantology, occlusion developed was similar to complete denture occlusion, avoiding anterior contact in centric relation and in lateral excursion. This eliminates anterior patterns of chewing and thereby, extruding forces on distal implants is avoided. The patient was seen every month for the first six months, with special consideration to the occlusion and hygiene (the pontics were relieved from gingival contact and there were open embrasures for purposes of cleaning). Thereafter, the patient was followed up every six months for clinical and radiographic follow-ups for 3 years (Figures 11 and 12).
Cortico-basal Implantology is currently the most favored and trending treatment modality in the field of dentistry owing to the fact that it is a minimally invasive technique. This technique is very patient- friendly since it aims towards restoring the function and form along with aesthetics in the edentulous maxilla and mandible. This technique is more advantageous in atrophic jaws where the entire treatment can be fast-tracked and also avoid grafting, which increases treatment time with unpredictable results.15-17 The Cortico-basal implant is anchored or engaged cortically by the surgeon into the dense basal (2nd cortical) bone, and the process of establishing this anchorage has been termed as “Osseo-fixation”.
However, for primary stability, i.e., for the treatment’s success, the macro-mechanic anchorage (Osseo-fixation) in the 2nd or 3rd cortical is imperative.18 Thereafter, a cross arch rigid splinting is done with the help of a prosthetic framework within 3 days that can help promote biological stability / osseointegration after remodeling of the bone within 6 months. Macro retention can be increased by tilting the implants. Cortico-basal implantology is based on the principle of engaging the basal bone from the nasal floor, maxillary sinus floor, walls of sinus, septa of sinus, wall of nasal cavity, palatal bone, crest of alveolar bone, pterygoid bone and zygomatic bone via aggressive threads that promote enhanced primary stability thus improving functional loading as well as through the smooth and small peri-mucosal penetration that helps resist infection.
It is reported in the literature that bicortical anchorage, i.e., engagement into the cortical bones on both the cervical and lateral sides, demonstrated better results when measured by resonance frequency analysis.19 The inter-foraminal region at the base of the mandible (2nd cortical bone) is accessible with long implants and lingual cortical engagement is more predictable since the bone is present in the compressive stress zone. Hence it has a greater predilection towards remodeling thus achieving the tenting effect. The guidelines involved in keeping a defined and bilateral balanced prosthetic situation (loading) include that only when a bilaterally identical anterior AFMP-angle (Planas’ Masticatory Functional Angles) is present, the chewing activity of the patient will be equal on both sides. Only if balance is present on both the sides of the distal mandible, will the development of a preferred chewing side be avoided. Otherwise. the side which is balanced during regular chewing, will be preferred sooner or later.
Peri-implantitis has been defined as a disease that is more severe and is defined as a more profound inflammatory lesion characterized by a deepened peri-implant pocket and loss of supporting bone around a functional implant. In analogy to gingivitis and periodontitis affecting the periodontium of natural teeth, the inflammation and destruction of soft and hard tissues surrounding dental implants is termed as mucositis and peri-implantitis.20 One of the primary drawbacks or limitations with regard to the use of conventional rough surface implants is the accompanying peri-implantitis disease, and currently, no treatment options21 are available to address it. However, this disease usually stops as it approaches the basal (i.e. resorption resistant) bone areas and since Corticobasal implants being smooth surface implants are anchored into the basal bone, peri-implantitis cannot occur, which is one of the major advantages associated with the use of corticobasal implants.
It can be inferred from the results of this case that Cortico-basal implants can be the treatment of choice that can be successfully selected while treating the atrophic maxilla and mandible. In our case, we achieved excellent results with regard to the immediate functional loading protocol. Furthermore, it presents as a good alternative to conventional implantology where applicable, and the protocol is very patient- oriented and friendly.
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