Immediate implants have become a popular option for replacing teeth. This article describes the surgical and restorative considerations involved in the planning and placement of an immediate implant. Immediate implants require appropriate hard and soft tissue assessment. Virtual planning can help assist in planning of immediate implants. Radiographic and computed tomographic guidance can help in establishing the relationship between the planned implant to the hard tissue and anatomic structures. This article discusses a technique in fabrication of the immediate provisional and final restoration.
Key points
- •
By reducing treatment time and number of surgical procedures, immediate implants have become a valuable alternative to tooth replacement.
- •
Meticulous surgical and restorative considerations can provide the ideal situation for an immediate implant placement.
- •
The steps described allow for fabrication of both the provisional and the final implant restoration.
The patient that is a candidate for immediate endosseous dental implant placement must meet high scrutiny. Careful planning and meticulous surgical and restorative considerations are paramount in ensuring the success of the immediate dental implant.
Before any implant evaluation, a review of medical history is important to identify any conditions that could affect surgical implant placement or healing. Systemic diseases are important to consider, as these conditions could affect implant healing. When evaluating a patient’s past medical history, the practitioner should take into account systemic diseases, such as diabetes and osteoporosis, and local insults, such as tobacco use and smoking.
Although these are only some of the systemic conditions that can raise red flags in a patient’s medical history, they are some of the most important to heed caution. These conditions may be relative contraindications for traditional 2-stage implant placement and make for a much less ideal candidate in the setting of immediate implant placement. A comprehensive informed consent process that includes a thorough review of all risks, benefits, alternatives, and complications is necessary.
Immediate implant placement is the sequence of placing an implant into a freshly extracted tooth site. There are many advantages to placing an implant immediately after extraction when compared with the more traditional delayed surgery. There are fewer surgeries required along with providing the option to place an immediate temporary restoration to avoid any esthetic compromises.
One of the key elements required in immediate implant placement is bone. There must be enough good-quality bone to engage the implant to facilitate stability for osseointegration. As a result, atraumatic extraction technique is paramount for immediate implant success. The use of periotomes and sectioning of teeth allow for well-preserved alveolar bone. Periotomes are used to expand and separate the gingival attachments from the tooth and periodontium. Atraumatic movements with careful luxation to prevent alveolar bone fracture is critical to maintain enough bone for implant placement. Multiroot teeth are commonly sectioned into their individual roots to allow for a less traumatic extraction.
More recently, piezosurgery units have been used for atraumatic extractions. Piezosurgery uses ultrasound frequencies in the range of 22,000 to 35,000 Hz to cut through bone. In addition, piezosurgical cutting allows for creation of a bone window if exposure is needed for an extraction. This bone window can later be used as an autogenous bone graft.
Preservation of bone, more specifically, preservation of the walls of the tooth socket will allow for a more predictable immediate implant. Not only is preservation of the walls of the tooth socket important but also maintenance of the furcal bone through atraumatic extraction is essential for immediate implant placement. Furcal bone can be used to help engage the immediate implant and obtain primary stability. In the anterior region, preservation of the buccal bone is essential in maintaining soft tissue contour.
A freshly extracted tooth socket will have up to 5 walls. Ideally, the buccal, lingual, mesial, distal, and apical walls remain intact after removal of the tooth structure. If all the walls are present after extraction, the site is known as a 5-walled defect. A 5-walled defect will provide the ideal environment for implant placement. A 4-walled defect, an extraction site missing one of the above, will usually require bone grafting at the time of implant placement. Although not ideal, it usually still allows for a suitable site for immediate implant placement. A 3-walled defect will likely need bone grafting before implant placement and is usually not amenable to immediate placement because of the lack of bone structure. There must be enough bone for the implant to engage and achieve primary stability for osseointegration.
Primary stability is determined by the amount of bone and quality of bone engaged to the implant. Primary stability can be determined through multiple methods. Some common methods of determining primary stability are through insertion torque or resonance analysis. Insertion torque values are measured in newton per centimeters (N/cm) and are commonly measured with the implant motor. Although there are many protocols available for insertion torque values in regards to implant placement, 30 N/cm is a commonly accepted insertion torque value to predict primary stability. At this time, there is no definitive value to predict for success in different loading concepts. Other quantitative measures include resonance frequency analysis. Resonance frequency analysis determines implant stability by sending a magnetic pulse through the implant, which is interpreted to a numerical value called the implant stability quotient (ISQ). The ISQ value measures the stiffness of the implant-bone interface.
Insertion torque values and bone volume have been positively correlated with resonance frequency analysis/ISQ values. Quality of bone can be defined by the amount of cortical bone and medullary bone available, or location in the jaw. The hard tissue evaluation incorporates the quality and shape of bone, the Lekholm and Zarb classification. This classification quantifies bone in 4 categories based on the amount of cortical and trabecular bone. Type 1 bone is large homogenous cortical bone. It is described as very dense with little blood supply compared with the other types of bone. Type I bone is found in the anterior mandible where there is mostly cortical bone. Type 2 bone is composed of a thick cortical layer surrounding a dense medullar bone. Type 2 bone can be found in the posterior mandible. Type 3 bone consists of a thin cortical layer surrounding a dense medullar bone. Type 3 bone can be found in the anterior maxilla. Type 4 bone consists of a thin cortical layer surrounding a sparse medullar bone. Type 4 bone is generally found in the posterior maxilla. This bone is considered to be very “soft” and can lead to higher failure rates.
Studies have shown the mandible (type 1 and type 2 bone) to have higher survival of implants when compared with the maxilla ( Table 1 ). The maxilla being type 3 and 4 bone has less cortical bone and more medullary bone. As a result, implants have less bone resistance/interface to stabilize. ISQ values of implants placed in the mandible have been found to be more stable than the maxilla. Achieving primary stability in immediate implants is critical to their success. Without obtaining primary stability, more traditional 2-stage techniques are more favorable.
| Classification | Composition | Location |
|---|---|---|
| Type 1 | Dense cortical bone, little medullary bone | Anterior mandible |
| Type 2 | Thick cortical bone and dense medullary core | Posterior mandible |
| Type 3 | Thin cortical bone with a dense medullary core | Anterior maxilla |
| Type 4 | Thin cortical bone with little medullary bone | Posterior maxilla |
Knowing the implant divergence or convergence is a critical part of the virtual plan, particularly for immediate implant placement. The trajectory of implant placement is not only determined by the amount of residual bone left after extraction but also determined by the position of the planned final restoration. For example, in the anterior esthetic zone, implants are ideally positioned just palatal to the incisal edge of the proposed restoration in an axial direction. Palatal positioning allows for screw access to be just palatal to the facial surface. An implant placed too facially will create a host of problems, including an unideal access position for the final restoration as well as possible bone loss and soft tissue recession. An implant placed too palatally can create a ridge lapped restoration leading to a hygienic problem. After placement of the implant, there will be a gap between the implant and the facial wall known as the labial gap. Studies have shown that grafting of the labial gap allows for improved preservation of the labial wall ( Fig. 1 ). The 3-dimensional position of the implant needs to be considered when deciding to place an immediate implant.
