Bone augmentation and implant restoration in a compromised aesthetic zone: a case report
Abstract
Purpose: This case report describes four routine treatment modalities in a single implant placement in the aesthetic zone. The protocol can be standardized to achieve the same result on similar cases in daily practice. This paper presents a proper staging of the treatment plan for any patient with deficient hard and soft tissue to achieve a beautiful result.
Keywords: Guided Bone Regeneration (GBR), Guided Tissue Regeneration (GTR), polytetrafluorethylene (e-PTFE), aesthetic zone, implant, periodontal defect, bone defect, membrane, onlay graft, allograft, xenograft
Materials and methods: Single case study patient who has been treated by the same clinician, surgically and restoratively, with large bone and soft tissue defect in an area of the aesthetic zone as a single implant case from 2016-2017. These treatment modalities include: 1) Guided bone regeneration (GBR) with e-PTFE and PRF 2) Guided Tissue Regeneration (GTR) 3) Implant placement and interim provisional restorations after the implant was fully osseointegrated and 4) Final screw-retained restoration.
Introduction
Implant rehabilitation has become the golden standard of care for the anterior maxillary area due to high percentage success and minimal invasiveness of neighboring teeth. Osseointegration is no longer an issue with the latest generations of dental implants. However, the aesthetic zone is still a big challenge to the practitioner. Success in implant therapy is mainly related to the positive appearance and correct harmony with the remaining dentition. Henceforth, different parameters would need careful consideration, such as the wellness of the soft tissue, volume, color, contour and the sounding teeth zenith. Various conditions cause periodontal tissue defects, and the goal is to reestablish the original environment with surgical procedures such as GBR and GTR.
GBR and GTR can be performed simultaneously with implant placement depending on the amount of bone loss and the volume of the soft tissue present. This volume deficiency of bone and soft tissue can be either anatomic or pathologic.
GBR grafting is one of the solutions for such problems, and it can be broken into two formats: block and particulate onlay grafting. The latter can further be divided into two categories: tunnel and direct particulate onlay grafting. In this clinical case, the focus is on onlay particulate GBR grafting.
Technique: GBR procedures can either be staged or simultaneous with implant placement. The host area is fully exposed with a full-thickness flap to visualize the defect. It is imperative to create a tension-free soft tissue flap by releasing incisions on both sides of the flap to increase site visibility and a tension-free flap closure.
GBR considerations:
The essential purpose of the GBR is to exclude the epithelial cells with a high turnover rate and to allow the migration of the osteoblastic cells to the proper site. This will include using a biological membrane to isolate the two compartments: soft tissue and bone particles. The main bone substitutes include autogenous bone, xenograft, allograft and alloplast. The ideal bone material is to create a balance between resorption and formation of the new osteogenic cells in the area of the GBR. In addition, space is required by the material in order for the process of healing to materialize. Autogenous bone is the golden standard due to osteogenesis, osteoinduction and osteoconduction abilities.
Xenograft or Deproteinized bovine bone (DBB)
Xenograft bone materials come from either cows, horses or species other than humans. Xenograft is used very frequently in GBR procedures today. These materials are osteoconductive and have an interconnecting pore system that serves as a scaffold for the migration of the osteogenic cells. The advantage of the DBB has close molecular similarities to the natural cortical bone. DBB particles are incorporated into the living bone over time, and they have a low turnover and substitution rate. Therefore, it provides long-term space maintenance which is an essential part of any successful bone grafting. It has been shown that DBB graft particles remain present even after ten years post-operative. This can be detrimental to the future of the implant due to excessive DBB contact than vital bone.
Allograft
Allografts are bone grafts obtained from the same species but are genetically dissimilar from the host. These materials go through an intense process such as freeze-drying to prevent the transmission of diseases. Mineralized allograft (MA) provides stability, space maintenance, and osteoconductive scaffolding to increase volume enhancement in the GBR site for successful implant placement. MA is composed of two types of material: cortical and cancellous bone. The cortical has a slower resorption rate than the cancellous component; therefore, in a case where the clinician requires the material to stay longer without resorption as a scaffold, he can increase the percentage of the cortical component of the bone mixture. In order to slow the process of resorption down even further MA can be mixed with DBB material.
The other important part of the GBR technique is the membrane. The membrane isolates the bone material from the soft tissue invasion. There are two types of membranes available: resorbable and non-resorbable. The membrane needs to provide barrier functions, safe biocompatibility and proper handling. They also need to have bioactive properties to promote and enhance tissue regeneration. Synthetic polymers manufacture non-biodegradable material with or without a metal component. The metal component is added to increase the integrity and to enhance the space maintaining ability of the membrane. The first non-resorbable membrane that was introduced to the market was made from expanded polytetrafluoroethylene (e-PTFE). The second category is a biodegradable membrane. They are made from natural and synthetic polymers. Collagen is one of the most commonly used materials in these membranes and is made by cross-linking methods. New materials such as aliphatic polyesters and other copolymers have been recently introduced into GBR procedures. In addition, inorganic materials such as calcium phosphate and bioactive glass have been incorporated in the research stage to help the membrane's regenerative abilities and strength. The main advantage of the resorbable membranes is the elimination of a second surgical procedure to remove the membrane. This reduces the morbidity of the procedure and lowers the rate of complications. However, regarding space maintenance, resorbable membranes are not as successful as the non-resorbable membranes.
Non-resorbable membranes are well documented in the literature. Research has shown a long-term success of 93% in over 12.5 years. Yet, one of the e-PTFE drawbacks is that the membrane must be removed prematurely in case of early exposure since the result will be the contamination of the bone and inflammation of the soft tissue.
Studies have shown that implant placement in conjunction with the GBR has a survival rate of 91.9%- 92.6% and 94.6% survival rate with the implants in the native bone without the GBR.
Soft Tissue considerations:
Soft tissue considerations are important for achieving an ultimate result in the aesthetic zone. Creating a functional result without an aesthetic component is unacceptable to the provider as well as the patient. The concern gets magnified with a patient who has deficient soft tissue due to anatomical or pathological problems. Numerous possible techniques have been introduced in the literature, including autogenous tissue graft, collagen matrix and dermal matrix. The golden standard is still the autogenous tissue graft to optimize the keratinized mucosa (KM). Studies have shown that KM thickness helps with the aesthetic outcome and creates a healthier environment for the long-term success of the dental implant. Healthy KM around the cervical aspect of the implant will create a biological seal that prevents bacterial invasion and provides better hygiene and comfort. The success of KM surgery is unrelated to the stage in which it was performed, whether during the implant placement or the GBR.
In cases of trauma, the process of tissue healing is very unpredictable, and most patients require tissue augmentation in addition to the GBR. Besides the aesthetic considerations, the thickness of KM can improve peri-implant health and marginal bone remodeling. Amongst the autogenous graft techniques, the Palatal Pedicle Flap (PPF) can improve the result due to preservation of the vascularity, which results in optimal coloration and less tissue shrinkage.
Platelet-Rich Fibrin
Platelet-rich fibrin (PRF) is a concentrate from a patient's own blood which is drawn in the office on the day of the surgery. PRF has become more popular amongst clinicians as an added layer over the GBR site in combination with more traditional membrane. This concentrate is pressed and flattened out to be used as a membrane and auto-scaffold in the GBR and other periodontal procedures around the implant or natural dentition. After the PRF membrane is delivered in the area, it releases growth factors including PDGF, TGF-, VEGF, EGF, FGF, and IGF. PRF membrane has better results than platelet-rich plasma (PRP), since the fibrin material releases the growth factors and cytokines during the healing phase.
PRF also has shown much better results in root coverage of natural teeth with gingival recession than the acellular dermal matrix.
Implant Position considerations
The implant placement needs to follow the three-dimensional approach: orofacial, mesiodistal, and apicocoronal.
In normal circumstances with thin biotypes and highly scalloped tissue, the implant needs to be placed more palatially and slightly deeper to hide the possible titanium showing through the soft tissue as healing occurs.
In addition, the rule of six that was introduced by Cooper et al, can be used in order to place the implant in a proper 3D location
- 6mm bucco-lingual osseous dimension
- 6mm in length at minimum
- 6mm of inter-radicular space
- 6mm in length at minimum
- 6mm interocclusal space
- Less than 6mm distance between the contact point and crestal bone; 6 mm of interocclusal space the implant needs to be placed 3 mm apical and 2 mm palatal to the gingiva. This provides the correct spacing for the single implant placement in the aesthetic zone.
The implant needs to be placed 1 mm below the cemento-enamel junction corono-apically. The orofacial position should be 2 mm from the midfacial gingival margin and 1.5 mm mesio-distal position from the adjacent teeth. In summary, the anatomical considerations for the successful implant placement requires at least 1 mm of bone all around the dental implant in the posterior area and for best aesthetic result 2 mm in the anterior buccal side.
Clinical Presentation
Forty-two years old male presented to our office with a chief complaint of "my tooth fell out.".
The patient reported that his tooth started getting loose on its own for the past two months. He also reported no significant medical history, medications, or allergies and denies a smoking history. After a complete oral examination, a lack of proper home care was noticed. The adjacent teeth had a typical probing depth between 2-3 mm, and the mobility was within the normal limits. The patient also presented with a thick band of KM and favorable bio-type with the papilla on the mesial and distal side.
This patient's expectation was to correct the defect and to replace his tooth with a dental implant to attain the best possible aesthetic outcome.
Case management
Phase I included a full mouth proper in-office hygiene and home care instructions.
3D Cone Beam Computer Tomography (CBCT) was taken before the surgery to assess the bone deficiency and create a proper approach to the case.
On the day of surgery, the patient was given post-op instructions, and consent forms were obtained. The procedure included GBR and GTR with adequate time to heal before the implant placement. The patient agreed to the staging and length of the treatment. The patient was premedicated one hour before surgery with 2 grams of Amoxicillin, 40 cc of venous blood was drawn and centrifuged at 450 rpm for 15 minutes. The collected PRF was compressed with a proper PRF box to collect the leukocyte-PRF membrane. The proper amount of local anesthesia with 4% septocaine with 1/100,000 epinephrine by way of infiltrations was administered. A full-thickness flap was made from teeth #6-11 with two sparing papillary releasing incisions.
Palatal tissue was reflected, and was dissected to rotate the KM flap to cover the bone graft site. As mentioned above the benefit of this technique is that KM tissue maintains its blood supply and therefore higher percentage of success.
The bone bed was fully de-epithelized and cleaned to remove any soft tissue with copious irrigation at the site of GBR; 0.5 cc Puros demineralized bone matrix putty with chips (Zimmer Biomet 1800 West Center St. Warsaw, Indiana USA) was mixed with 0.5cc cortical bone allograft .25-1.0 mm and .25 g Maxxeus xenograft, (Maxxeus dental material 2900 College Drive Kettering, OH 45420 USA). All three materials were mixed equally and hydrated inside the PRF growth factors.
Before placing the graft, the Cytoplast Ti-250 titanium-reinforced membrane, (Osteogenic Biomedical Inc 4620, TX 79424 USA) was fixed at the buccal side with 2 BioHorizon tacs (2300 Riverchase center Birmingham, AL 35244 USA) to secure the membrane.
The area was grafted and the membrane was secured to the lingual side with a 2/5 mm Osteomed screw (Osteomed 3885 Arapaho Road Addison TX 75001 USA) to create a better membrane stability. The immobilization of the membrane translates to an undisturbed graft and naturally better quality of healing.
The palatal tissue was rotated over the membrane. A 5.0 chromic gut, (ACE surgical supply Co 1034 Pearl St. MA 02301 USA), was used to secure the KM graft to the inside of the mucosa on the buccal side.
Before the closure, the PRF membranes were placed over the site and primary closure was attained.
Follow-up was recommended 7, 14, and 21 days after the surgery. Wound cleaning with the clinical examination was done during those visits. The patient was advised to rinse with chlorhexidine gluconate mouthwash twice a day. During the soft tissue healing period of 2 to 3 weeks, plaque control was done with chlorhexidine gluconate (.012%) as recommended. Mechanical toothbrushing was not advised at the surgical site for 4-6 weeks. The remaining sutures were removed 14 days after the surgery.
The patient was given an option of delaying the temporary tooth by 6-8 weeks into his healing period to allow the tissue maturation in order to have better adaptability of the provisional to the adjacent teeth and soft tissue. The patient agreed with our recommendation. A Maryland bridge was manufactured for the patient, and it was bonded with a single wing to the left central incisor (tooth #9).
After six months of healing, the patient was scheduled for the implant surgery. The same pre surgical protocol was followed prior to the GBR. A full-thickness flap with a single papilla sparing incision was made and the cytoplasm membrane was removed.
Osteotomies were prepared for a single implant, EBI BLT tapered effect implant (EBI Implant System Seoul, Korea) was placed in a 3D format so the prosthetic access hole can be on the lingual side. Primary closure was attained, and post-operative instructions were reviewed with the patient.
After 4 months of healing during stage two, the crestal tissue was de-epithelialized, a semilunar incision was made, sparing the papillae, and the tissue was rotated under the buccal side to increase the thickness of the soft tissue. Proper healing time was allowed before the start of the final restoration.
A 4.8(D)xC2x4.5(H) BestSolid abutment, (EBI Implant Seoul, Korea), was placed and hand tightened, a new lab fabricated provisional crown was relined over the abutment, and temporarily cemented. The goal of re-provisionalization is to directly load the implant with a new lab fabricated temporarily to mimic the anatomical and aesthetic characteristics of the tooth that is being replaced. After every successful implant placement in the aesthetic zone, it is vital to provisionalize in order to develop the desired architecture of the soft tissue and the emergence profile. Dental implants differ from natural teeth in size and shape. When the healing abutment is removed after the implant has healed, the tissue is in circular shape and does not match the natural tooth's shape at the crest; this problem is magnified with the central incisors. For the best result, this part of the treatment should not be overlooked. After multiple surgeries, the area of the implant and soft tissue needs to be retrained to accept the fixed crown, and this will allow the clinician to recreate the proper zenith of the soft tissue. This process requires 4-6 weeks before re-evaluation of the site prior to final restoration.
Single crown screw-retained restoration was fabricated. The crown was inserted, and the screw was torqued to 35 Ncm according to the company's recommendation.
Over the course of five years the patient has followed up with implant maintenance including intra-oral X-rays and pictures to ensure the health of the implant.
Discussion
Every aspect of a dental implant treatment builds on top of each other as the clinician drives the therapy forward. The following factors influence the outcome of any aesthetically driven case, from successful GBR and GTR to positioning the implant in a 3D fashion as a foundation for the final restoration. Another important consideration is the location of the contact point for the presence or absence of the interproximal papilla. Ultimately, it has been established that implant dentistry is a restorative-driven discipline with a surgical component attached to it. The aesthetic outcome can be compromised even with a successful bone, soft tissue augmentation, and implant osseointegration if the vital component is not well premeditated. After a strategic surgical workflow, the restorative component can still be challenging in the aesthetic zone. Maintaining the papilla in the aesthetic zone is of the utmost importance. The patient's perception of the papilla is subjective. The threshold of an unattractive papilla where the clinician and the patient agree is within 3 mm of the open gingival embrasure.
The provisional stage of the treatment is the outmost crucial stage of the restorative part. There are many ways to remold the soft tissue to accomplish the optimum result with the provisional in the aesthetic zone. The provisional needs support in some areas and applied pressure in other areas to accomplish the proper result.
Conclusion
The hardest part of any treatment plan is to predict the final result before the work has begun. The clinician needs to understand their limitations in the science of dental implantology while treatment planning their patients. Correct data gathering before the treatment is the key to any clinical success. Each case needs to be re-evaluated based on the individual. The treatment plan has to be customized for the patient and staged properly for the optimum result. The success of this case was based on a proper diagnosis, treatment planning, well-organized data gathering and adequate staging of the case. Although, in this case, with a low lip line there is more forgiveness in the aesthetic outcome. The authors were trying to create an appropriate protocol for future implant cases in the aesthetic zone. Every patient presents itself with different challenges and the clinician needs to use an appropriate judgment of how to approach each case. Additional case reports, documentation, and long term follow-ups need to be done in order to present a definitive protocol on how to approach aesthetically compromised patients.
