In last three decades dental implants have totally changed the face of dentistry. Dental implant therapy has become one of the most suitable treatment options for replacement of missing teeth. The main reason for this is high rate of success and long term stability of implant treatment. In spite of high success rate, failures are also encountered during implant therapy. According to my clinical experience, the diagnosis and treatment planning of an implant case is one of the most important steps in long term success of implant therapy. Right from initial consultation to the execution of treatment plan, the clinician should have clear picture in his mind about final outcome of the treatment. Medical and dental history of the patient, clinical examination, radiographical examination, study of the diagnostic models and wax up provide a lot of information about the case. If all these examinations are thoroughly done, there are fewer chances of complications during and after the treatment. In the following sections we shall discuss in detail all the steps which are required to make a correct diagnosis and the treatment planning of an implant case.
Initial consultation with the patient:
Initial consultation with the patient plays a very important role in treatment of the patient. First of all, we must know what kind of a patient we are dealing with rather than what kind of problem the patient has. The patient should be asked about the reason of his/her visit to the dentist. Usually patients opting for implant therapy are already wearing partial or complete denture. Patient usually says that “ I am wearing denture for last 10 or 15 years and they are no longer helping me as they are loose/ do not chew food properly/ do not look esthetically good. Because of wide publicity of implant treatment, some patients have unrealistic expectations. It is important that patient should not be promised anything at this stage. Only after thorough examination and investigations when you are sure about the expected clinical results, the practically possible outcome of the therapy should be told to the patient. The patient should be explained in detail about the surgical and non-surgical procedures involved in the treatment.
One important thing here, is the duration of the treatment. Some patients have a perception that implant therapy is a single sitting or few sittings treatment. Except when we are doing immediate loading for single or few teeth, most of the time implant therapy is two stages where the implants are placed in the first sitting and prosthetic rehabilitation is done 4-6 months later. The prosthetic part may take two or more than two sitting depending upon the complexity of the case.
Some patients do not agree for diagnostic procedures like CT scan etc. They should be explained the importance of these investigations in detail. If still the patient does not agree for the investigations, you should refuse for the treatment. In elderly patients the primary aim of implant therapy usually is function and not esthetic. The availability of bone is the prime requirement for long term stability of implants under occlusal load. Thorough examination of the oral cavity is important before explaining any treatment to the patient.
It is important that patient should be explained about all the treatment options by which we can treat the patient. The replacement of the missing teeth by bridge or implants should be explained with regards to the various factors such as difference between the bridge and implant treatment, differences between implant and natural tooth, treatment cost of various treatments etc.
An informed consent which includes details about the procedure that is going to be followed during the surgery as well as all the complications that may happen during the treatment should explained to the patient and consent form should be signed by the patient. This step is very important from medico-legal point of view.
After the initial consultation is over and the patient agrees for the treatment the detailed examination of the patient starts with a case history taking. The steps involved in the diagnosis of an implant patient are:
- Chief complaint
- History of present illness
- Past medical history
- Past dental history
- Clinical examination of the patient
- Radiographic examination
- Study of the cast models
- Treatment planning
The chief complaint of the patient may be one or he/she may enumerate multiple problems. Usually, in present scenario the patient describes multiple problems at a time. For example the patient says that I can no more eat properly with the existing denture, esthetically also it does not look good, I look older than i am actually etc. All the active problems of the patient should be recorded and should be discussed in detail by asking the patient relevant questions.
History of present illness:
The patient should be asked about the initiation of the present problem/problems. All the factors which led to present situation should be identified, especially in cases in which atrophy in the maxilla or mandible is severely advanced. If the patient has advanced bone loss in maxilla or mandible or both, the period of edentulism should be noted. Some patients are edentulous for decades and have been wearing dentures for years. The reason for loss of teeth should be identified i.e. whether teeth were extracted due to endodontic problem or periodontal problems. Any pathology such as cyst or tumor in maxilla of mandible for which patient was operated should be identified. Any traumatic injury to orofacial structures should be noted. Patient’s awareness towards oral hygiene maintenance should be evaluated.
Past medical history:
The first to be recorded during the medical history are the vital signs such as (blood pressure, pulse, and respiration) which are recorded in the patient’s chart. The patient should be asked about all the medical problems for which he/she has been treated in past or is under treatment presently. Research work has shown that medical conditions can significantly affect the healing process and osseointegration of implants 1-6. Systemic conditions may affect the implant therapy by two ways: By increasing the susceptibility to other diseases (HIV) and by delaying the healing process (Type II diabetes).
Before we discuss the implant therapy in different medical conditions let us first discuss physical status categories of the Classification System of the American Society of Anesthesiology (ASA). The ASA score is a subjective assessment of a patient’s overall health that is based on five classes (I to V).
Class I: Patient is a completely healthy fit patient. Patient has no organic disease or in whom the disease is localized and causes no systemic disturbances.
Class II: Patient has mild systemic disease. Slight to moderate systemic disturbance which may or may not be associated with the surgical complaint and which interferes only moderately with the patient’s normal activities and general physiologic equilibrium.
Class III: Patient has severe systemic disease that is not incapacitating. Severe systemic disturbance which may or may not be associated with the surgical complaint and which seriously interferes with the patient’s normal activity.
Class IV: Patient has incapacitating disease that is a constant threat to life. Extreme systemic disturbance which may or may not be associated with the surgical complaint, which interferes seriously with the patient’s normal activities, and which has already become a threat to life.
Class V: A moribund patient who is not expected to live 24 hour with or without surgery.
Class VI: A patient who is considered brain dead and is a potential organ donor.
Patients receiving dental implants generally fall into the first two physical status categories of the Classification System of the American Society of Anesthesiology (ASA). Buser and coworkers (2000) 7 during second ITI (International Team of Oral Implantology) Consensus Conference proposed two groups for genral medical/systemic risk factors:
Group 1 (very high risk):
Patients with serious systemic disease (rheumatoid arthritis, osteomalacia, osteogenesis imperfecta); immunocompromised patients (HIV, immunosuppressive medications); drug abusers (alcohol); noncompliant patients (psychological and mental disorders).
Group 2 (significant risk):
Patients with irradiated bone (radiotherapy), severe diabetes (especially type 1), bleeding disorders (hemorrhagic diathesis, drug-induced anticoagulation), heavy smoking habit.
It is important to note that medical conditions may vary in their severity. For example a diabetic patient may have severe hyper glycaemia or he may be a well controlled diabetic patient. In a well controlled diabetic the results of implant therapy are as good as a normal patient whereas a uncontrolled diabetic patient complication with the healing process around implant. Following is the list of conditions which are contraindications for implant therapy and must be controlled before planning for implant surgery.
Systemic/medical contraindications for implant therapy:
- Severe haematological disorders (hemophilia etc.).
- Severe immunodeficiency.
- Patients who are undergoing strong chemotherapy.
- Cerebral infarction where condition of the disease is serious and the patient are concurrently taking anticoagulants.
- Myocardial infarction: within six months of an attack.
- Severe neuropsychiatric disease, mental disability, and narcotic drug addicts.
- Patients who are concurrently taking bisphosphonates.
The patient should be advised haematological, biochemical and coagulations tests before planning for implant surgery. If there are any variations from normal, they must be recorded and appropriate treatment should be done.
Implant therapy in diabetic patient:
Diabetes is currently classified as a relative contraindication for implant treatment. Compared with the general population, a higher failure rate has been seen in diabetic patients with adequate metabolic control 8. In a prospective study in which 89 well-controlled type 2 diabetics in which a total of 178 implants had been placed reveals early failure rates of 2.2% (4 failures), increasing to 7.3% (9 further failures) one year after placement, indicating a survival rate of 92.7% within the first year of functional loading. The 5-year survival rate was 90% 9. High plasma glucose levels in diabetic patients present a problem during healing after implant therapy. Diagnosis of diabetes relies on at least 1 of 3 criteria:
1. Symptoms such as polydipsia (excessive thirst), polyuria (increased urination), and polyphagia (excessive eating) in correla-tion with blood glucose levels that exceed 200 mg/dl.
2. Fasting blood glucose levels equal to or more than 126 mg/dl.
3. Blood glucose levels that exceed 200 mg/dl after a standard glucose load.
Various mechanisms have been suggested by which diabetes interferes with the wound healing 10, 11. Animal experiments show reduced rates of bone-to-implant contact in stages of the healing process, which correlate to the duration and severity of hyperglycemia 12-16. The advanced glycosylation end products (AGEs) formed in diabetes have been found to cause extra-cellular matrix component alternations such as collagen, laminin, and vitronectin; they also disturb cell adhesion, growth, and matrix accumulation 17.
During implant placement osteotomy is performed at the site which is accompanied by blood clot formation in the space between the implant and the bone. Hyperglycemia, in the diabetic patient reduces clot quality by interfering with proteins inherent to the process. Osteoclastic absorption of the bone surrounding the implant takes place in next step. In diabetic patients, osteoclasts are fewer and less effective than in people without diabetes. After bone absorption, new bone matrix is laid, a process mediated by collagen production, which is also delayed in diabetes 18, 19.
New bone formation and mineralization initiated by osteoblasts and mediator proteins are also reduced in diabetes. Following bone formation around the implant, osseointegration, which is important to prevent implant failure, is enabled. There is constant bone remodelling around implant during healing process which is hampered by hyperglycemia 20-22.
Review of literature on effects of diabetes on osseointegration:
The effects of diabetes on osseointegration have been studied in animal experiments. As stated earlier, diabetes alters the bone remodelling process around implant. Studies have shown that although the amount of bone formed is similar when comparing diabetes-induced animals with controls, there is a reduction in the bone-implant contact in diabetics 23, 24. So, diabetes inhibits osseointegration. This situation may be reversed by treating the hyperglycaemia and maintaining near-normal glucose levels 25. Studies have also confirmed that osteopenia associated with diabetes induced in animals can be reversed when treatment with insulin is applied 26. It is recommended that an uncontrolled diabetic should be treated first for diabetes before going implant therapy.
Before going for any surgical procedure, the routine haematological tests are mandatory. Many bleeding disorders such as haemophilia, aplastic anemia, leukemia and thrombocytopenia have to be taken into consideration as prolonged bleeding can occur in these cases if issue is not addressed before surgery. In the case of mild haemophilia, bleeding during the procedure can be controlled with the application of blood products and local haemostatic measures (suture, compression, the use of hemostatic microfibrilar collagen gauzes, oxidized cellulose, reabsorbable fibrin, or mouth rinsing with 4-8% of tranexamic acid). Many patients are on anti-coagulant therapy. Best way to determine whether to discontinue the anticoagulant therapy is finding out the International Normalized Ratio (INR). The INR is the prothrombin time (PT) ratio (patient PT/control PT) that would have been obtained if an international reference thromboplastin reagent had been used. For a PT within the normal range, the INR is approximately 1. If International Normalized Ratio (INR) is < 2.5, there is no need to discontinue the anti-coagulant therapy. The British Committee for Standards in Haematology advises that minor surgery can be performed with an International Normalized Ratio (INR) of up to 2.5 27.
In case of platelet disorders such as thrombocytopenia, the reduction in the platelet counts can result in bleeding and abnormal blood coagulation. Blood platelet count and their functions should be monitored and if required surgery should be postponed till platelet count comes under normal range or brought under normal range.
Hypertensive patient present a risk of excessive bleeding during the surgery. A systolic blood pressure (BP) over 140 mmHg and the diastolic BP over 90 mmHg (140/90 mmHg) indicates hypertension. If the patient is hypertensive he/she should be referred to a physician for controlling the blood pressure. During surgery, measures such as the administration of minor tranquillizers from the day before, or relaxing the patient during surgery to avoid the rise in the BP are necessary. If the blood pressure rises above 200/120 mm Hg the implant surgery should be discontinued.
The use of sublingual nifedipine has been contraindicated to lower the blood pressure because of risk of inducing rapid fall in BP and reflex tachycardia. In cases where BP needs to be controlled immediately, intravenous administration of anti-hypertensive with close monitoring is required.
Myocardial infarction, cerebral infarction and stroke:
The implant treatment should not be done within six months of myocardial or cerebral infarction. The patients who had myocardial infarction, cerebral infarction or stroke are usually on medications which should be checked and physician should be consulted before going for any surgical intervention.
Osteoporosis is a systemic disorder characterized by generalized decrease in bone mineral density. The National Institutes of Health Consensus Panel on Osteoporosis Prevention, diagnosis and Therapy (2009) 28 defined osteoporosis as a skeletal disorder characterized by compromised bone strength predisposing a person to a n increased risk of fracture. Osteoporosis has been described as a multifactorial age related metabolic bone disease characterized by low bone mineral density, the deterioration of the microarchitecture of cancellous bone, and changes in the material properties of bone, leading to enhanced bone fragility and to a consequent increase in the risk of fractures 29.
As classified by Lekholm and Zarb 30, Bone quality type IV is believed to be unfavorable for osseointegration possibly because of the marked porosity of bone, because this may offer little mechanical anchorage to the implant to ensure its stability. The implant failure rate in such sites has been reported to be greater than that in the bone qualities type I to III 31, 32. The affects of osteoporosis on bone healing has also been studied. The histomorphometric studies have shown that bone remodeling is normal in a large proportion of patients diagnosed as being osteoporotic 33, 34.
Past dental history:
Past dental history of the patient includes details about the dental treatment that the patient has undergone in the past. Patient’s attitude towards the previous dental treatment, previous periodontic, endodontic or surgical treatment as well as frequency of visits should be asked. Any complication during previous treatments should be noted. If surgical treatment for any pathology in the oro-facial region was done, its details are required.
The reason for tooth loss should be elicited. Usually the patients who had loos of teeth due to periodontal diseases have more bone loss due periodontal destruction. This is especially significant in case of fully edentulous cases. Along with this the duration of edentulism should be asked. It is easy to replace a recently extracted tooth as hard and soft tissue is usually available for construction of FP-1 or FP-2 prosthesis. But, in case of long standing extraction space where the soft and hard tissue loss is more, especially in the maxillary anterior region the fabrication of the prosthesis is difficult to achieve functionally and esthetically good results. Long standing edentulous space in maxilla and mandible raises maxillary sinus and neurovascular concerns respectively.
Clinical examination of the patient:
A thorough clinical examination is must to properly diagnose a patient and plan for implant treatment. The number of teeth present as well as their condition is examined. Many options can be explored while examining the remaining teeth. It must be remembered that the method of rehabilitation depends on the number, arrangement, and status of residual teeth (eg, periodontal health, remaining tooth structure); cost; patient desires; and adequacy of the bone to support dental implants.
Examination of teeth:
Number of teeth present:
Single tooth replacement is comparatively easy to plan than multiple teeth replacement. All the teeth present should be preserved and whenever possible every effort should be made to restore them. More the teeth present, more are the chances for long term survival of the implant.
Arrangement of teeth:
An arrangement of teeth conducive for an efficient occlusal load distribution is always helpful in the treatment planning. Sometimes, the teeth are positioned in such a way the prosthetic rehabilitation of the implant becomes very difficult. The inter-arch distance is commonly reduced due to the supra-eruption of the teeth of opposite arch due to long term edentulism. This can lead to a clinical condition where the implant therapy is very difficult to perform.
In cases where deep bite is present the occlusal evaluation must be done to evaluate the position of the implant and the associated superstructure. If it is appreciated that occlusal harmony cannot be achieved it is better to go for orthodontic treatment to relieve deep bite and re-evaluate the case.
Status of residual teeth:
The remaining teeth should be evaluated for their health status. A tooth with good periodontal health and bone support can be utilized as abutment for implant-tooth supported prosthesis. All the teeth with poor prognosis should be extracted. Teeth which can be restored but have a questionable long term prognosis should be treated separately and not included as abutment for fixed prosthesis.
Examination of the edentulous area:
The shape of the ridge in edentulous are is one of the most important factors determining the planning of implant treatment. In long standing edentulous areas the alveolar bone loss is evident. This is a major problem as sufficient bone support is required for long term success of implant therapy.
The size and the number of the implants are determined by the length of the edentulous span as well as the width of the available bone in area under consideration. In cases of advanced bone loss, the width of the available bone is not sufficient to support the implant with minimum acceptable width for that area. In such cases the bone augmentation is required to increase the dimensions of the implant supporting bone.
Unfortunately, areas where high occlusal forces are subjected (maxillary and mandibular posterior areas) the availability of bone is often less. This deficiency is further enhanced by long standing edentulous period. Maxillary sinus uplift and mandibular nerve lateralization procedures have been used in such cases.
Periodontal health is essential for the long term success of implants in partially edentulous cases. Systematic probing is done around all the remaining teeth to find out the pocket depth and the loss of attachment. Along with this, furcation involvement, mobility, trauma from occlusion, recession and any other significant periodontal findings are recorded. In case where the periodontal surgical and regenerative procedures can improve the prognosis of the tooth, they should be included in the treatment plan. Pocket reduction surgical procedures should be carried out to reduce pocket depths as well as bone recontouring where indicated should be done to minimize the chances of pocket formation in the future. Every effort should be made to the area self-cleansable by the patient. The detailed description of periodontal examination is available in “The art of history taking in periodontology”.
It is important to analyse the smile of the patient when restoring an anterior tooth. Esthetic concerns in the anterior area make smile analysis compulsory. The amount of tooth surface and gingival tissue displayed during speech and smiling is determined by the tonus of the orofacial muscles that inﬂuence the movement of the upper lip. While smiling the position of the lip line should be noted because it is important to deliver the restoration as expected by the patient. The high smile line poses greatest concern for implant-supported single-tooth restorations in the aesthetic area. It is a challenging task as the restoration as well as gingival tissue is completely displayed and the soft tissue contour, color and shape of the restoration need to be perfectly reconstructed. The arrangement of teeth including their size as well as positions should also be recorded.
Diagnostic imaging provides us a lot of information about the area under investigation. With the help of present technology both the available bone as well as its density can be determined by radiographic techniques. Several imaging techniques are available today for pre-surgical and post-surgical examination. The detailed description of different imaging techniques is available in “Diagnostic imaging in implantology”.
Study of the cast models:
Mounted study cast models are extremely important for diagnostic point of view. They demonstrate the actual maxillomandibular relationship. The actual replication of this relationship on an articulator allows us to visualize the final prosthesis. The measurements can be done easily to determine the position, size and number of implants required. Diagnostic wax-up of the intended prosthesis is done on these models for pre-treatment evaluation of desired occlusion. Surgical templates can be fabricated on these models to facilitate the positioning of the implants during surgery.
Information provided by diagnostic cast articulation
|Edentulous ridge relationships to the adjacent teeth and opposing arch.|
|Tooth position of potential abutments, including inclination, rotation, extrusion, spacing, and esthetic considerations.|
|Number of missing teeth.|
|Parallelism of abutments.|
|Tooth morphology and structures of potential abutments.|
|Direction of the force in future implant site.|
|Present occlusal scheme.|
|Edentulous soft tissue angulations, length, width, locations, and per mucosal esthetic position.|
Certain situations that do not allow us to place implants:
- Insufficient bone for implant placement
- Destructive parafunction
- Poor hygiene and motivation
- Very abnormal ridge relations
- Inadequate interocclusal space
- Severe T.M.J. or occlusal disharmony
- Active, destructive periodontal disease
After thorough examination and investigations an appropriate diagnosis is made and a treatment plan is formulated to resolve the chief complaint of the patient. It is important to note that most important reason for implant failure in implant dentistry is improper diagnosis which ultimately results in inappropriate treatment plan. Once the diagnosis is made, the prosthesis most suitable for a given situation is planned. It must be remembered that the implant positioning is guided by the prosthesis to be delivered. All these aspects of treatment planning have been discussed in detail in “Treatment planning for implant patient: A general overview”.
From the above discussion it is clear that every step right from the first consultation with the patient till treatment planning is equally important. Patient must be examined carefully considering all the local and systemic factors which may affect the treatment plan. Diagnostic models and wax-up provide useful information regarding available space and positioning of implants. Radiological examination is the cornerstone for proper diagnosis of an implant patient. If all the above factors are taken into consideration, there are minimal chances of misdiagnosis which reduces the chances of intra-operative and post-operative implant complications.