A thorough history and clinical examination are essential when planning to replace teeth with dental implants. Prior to surgery, both clinical and radiographic site-specific assessments must be carefully conducted. These assessments will provide the information required to formulate a detailed and individually tailored treatment plan that is likely to meet the realistic expectations of the patient. Therefore, a comprehensive examination is mandatory to anticipate any complications that may result from the treatment. In this module, we will discuss the recommended site-specific examinations and their relevance to patients who may be considering replacement of a tooth or teeth with dental implants. The site-specific assessments that will be discussed in this module are the restorative space and its characteristics, anatomical factors, and hard and soft tissue including any pathoses in the area.

After completing this ITI Academy Module, you should be able to: assess the restorative space and its characteristics, assess the relevant anatomical factors, assess the hard and soft tissue, and select the appropriate assessment tools and techniques.

The replacement of a tooth with a dental implant is the final end-point of treatment. Therefore, a prosthodontically driven site assessment and treatment planning underpin overall treatment success. Assessment of the restorative space and its characteristics makes it possible to determine whether there are any space limitations. It also makes it possible to anticipate treatment complexity and to assess the risk of complications.

The examination should assess whether the three-dimensional space is adequate for the prosthetic tooth replacement and allows use of the necessary surgical and prosthodontic instrumentation. Irrespective of whether the gap is in the anterior or posterior region, the examination should include specifically: the mesiodistal space, the buccolingual space, the interocclusal space, and the interradicular space or - in other words - the proximity of adjacent roots.

Examinations, particularly in posterior regions of the jaw, can often be difficult. Therefore, accurate casts, which are appropriately articulated, are usually invaluable to a proper assessment. Further aid is provided by a diagnostic tooth set-up or wax-up, particularly when multiple teeth are to be replaced.

Clinically, we measure the mesiodistal space between adjacent teeth in millimeters. A defined minimum amount of space should be available mesiodistally to replace a tooth with an optimally sized prosthetic reconstruction, particularly in the esthetic zone. As a consequence, the size of the tooth will determine the ideal diameter of the planned implant. For example, a lateral incisor should be replaced with a narrower diameter implant than a molar. A minimum distance of 1.5 mm between the implant and the adjacent tooth should be maintained in order to prevent complications and damage to the tooth and its root. An implant that fails to respect this requirement will cause resorption of the interproximal alveolar crest to the level of that implant. If the interproximal alveolar crest resorbs, the overlying interproximal papilla will also do so, since the papilla is supported by the bone. Also when replacing multiple teeth, this measurement will reveal the size of teeth to be replaced, which in turn will determine the number and optimal diameters of the implants to be placed.

Loss of teeth may allow the adjacent teeth to drift into the edentulous space. Consequently, the result is a space that is inadequate for ideally sized tooth reconstructions. A diagnostic wax-up will make it possible to visualize the final prosthetic tooth size and also, potentially, to correct minor discrepancies. In order to avoid an esthetic compromise, supplementary treatments, like orthodontic interventions, might be necessary to re-establish sufficient space.

Once a tooth has been extracted, a natural process of alveolar width reduction takes place. Research suggests a loss of ridge width of up to 50% within the first year. As can be seen in this clinical picture, the buccal alveolar ridge is concave and volume loss is evident. Such a reduced bone volume, if not adequately augmented, will result in an incorrect and more palatal position of the implant.

The amount of interocclusal space - which is the space from the crestal mucosa of the implant site to the opposing dentition - also has to be measured. This requires assessment of the overall volume of space with the teeth in occlusion. As well as analyzing for overjets and overbites, you should also look for any overeruption of opposing teeth, and for labial migration particularly in the mandibular incisor region. In the example shown here, you can see that the mandibular canine has significantly overerupted. This may lead to difficulties in replacing the missing maxillary canine with any type of prosthesis. It will also influence whether the prosthesis will be screw- or cement-retained. As a general rule, an interocclusal space of at least 4 mm is desirable for a straightforward implant restoration. Implant systems may vary in this respect so it is wise to check with the manufacturer. A compromise on interocclusal space may also affect the esthetic outcome of the implant prosthesis.

In the posterior region, a limited interocclusal space may represent an absolute contraindication for implant therapy. From a prosthetic point of view, an implant restoration requires enough space for the abutment and the overlying crown. Therefore, a certain minimum interocclusal space is necessary to achieve this. The case illustrated here is an extreme example where the mandibular molars have significantly overerupted and barely any space is available in which to replace the maxillary teeth.

Loss of interocclusal space is often noted in patients with tooth wear, which is also known as tooth surface loss. Irrespective of the etiology, whether due to attrition, erosion or abrasion, shortened teeth and the subsequent lack of interocclusal space are often encountered. Therefore, a more holistic treatment plan should be considered.

Apart from intracoronal and mesiodistal space, a minimum interradicular space between adjacent teeth is necessary to prevent damage to the periodontal ligament and roots of the adjacent teeth due to implant placement. In the two radiographs with superimposed implant templates, the proposed implant diameters seem to be encroaching upon the adjacent roots. An orthodontic treatment may be indicated to create sufficient space for an implant, or an alternative non-implant restoration should be offered to the patient.

Prosthodontic Space and Characteristics, Key Learning Points: A thorough assessment of the treatment site is imperative to identify any limitations and to anticipate the risk of complications. A three-dimensional assessment should be performed and should include measurements in the following dimensions: mesiodistal, buccolingual, interocclusal and interradicular.

Next, we will focus on the anatomical factors that have to be assessed. In order to prevent complications, the clinician should be familiar with the anatomy of the local site. Apart from avoiding damage to the adjacent teeth, there are various anatomical structures in the maxilla and the mandible that should be considered in the clinical assessment. In the maxilla, the following anatomical structures may influence implant placement: The alveolar ridge height up to the floor of the maxillary sinus, the nasal floor and the proximity and size of the incisive foramen and nasopalatine canal.

The floor of the sinus may extend so far down into the alveolar bone that there is not enough bone height left to insert an implant. In this cone beam computed tomography image, the thickness of the bone at the crest of the ridge is only 2 mm, which is too small to place even the shortest implant available. Therefore, a bone augmentation procedure may be necessary. These diagrams depict this procedure, in which the sinus is entered and a bone substitute is placed underneath the sinus membrane to increase the height of the alveolar ridge.

In the anterior maxilla, the floor of the nose is a natural structure that has to be considered when planning to insert implants. Unlike in the maxillary sinus, bone augmentations to increase the ridge height at the nasal floor are not straightforward procedures and are very rarely indicated or recommended.

The height and width of the alveolar bone on the labial and distal sides of the incisive foramen and the nasopalatine canal may determine whether an implant can be placed in the correct three-dimensional position. Therefore the dimensions of bone in the vicinity of these two structures have to be assessed carefully. In this clinical example, the incisive foramen and the nasopalatine canal are large in size and located anteriorly. They are likely to interfere with implant placement.

In the mandible, the following anatomical structures may influence implant placement: The position of the mental foramen, the position of the inferior alveolar canal, the inferior border of the mandible and the lingual concavity.

The mental foramen, indicated by the arrow superimposed on the tomographic view, which opens apically to the lower premolar region is an important landmark. The position of the foramen should be accurately identified to prevent damage to the neuro-vascular bundle, which exits the foramen. If necessary, three-dimensional imaging may be indicated when plain film radiographs do not deliver sufficient information.

Distal to the mental foramen, the position of the inferior alveolar canal should be identified if implants are to be placed in this region. This is important to prevent damage to the neurovascular bundle. A distance of at least 2 mm from the canal should be ensured to avoid complications.

In a resorbed or severely resorbed mandible, the inferior border of the mandible may limit the implant length, and therefore careful examination and evaluation of the bone height is necessary. This clinical example demonstrates a post-treatment complication in which the implant breached the inferior border of the mandible by several millimeters and resulted in a chronic extraoral fistula.

Often there is a lingual concavity, particularly in the posterior mandible as seen here on a CBCT. This is a limiting factor when planning implant therapy. It is important to identify this factor, although it is not always easy to identify it by manual palpation because it can be so deep as to be very uncomfortable for the patient. Three-dimensional cone beam computed tomography or CBCT imaging is therefore recommended since perforations of the lingual cortex during implant-bed preparation can have serious consequences, for example a sublingual hemorrhage that can cause obstruction of the airway. The intraoral, two-dimensional radiograph clearly demonstrates presence of a carious lesion but it is unable to detect a lingual concavity.

Anatomical Factors, Key Learning Points: Anatomical landmarks should be identified to avoid damage to teeth, neurovascular structures and perforation of maxillary sinus or mandibular lingual cortex. For more information on the basic anatomy of the facial region and an overview of the important structures involved in implant dentistry, view the ITI Academy module 'Anatomy with Relevance to Implant Surgery.'

Next we will look at hard and soft tissue and will first focus on bone. Examinations should include assessment of alveolar bone height and width. The available bone height directly influences implant length. For example, in this case the alveolar ridge height is reduced as a result of crestal vertical bone resorption and of the inferior position of the maxillary sinus floor. Accurate measurement of the alveolar bone height and selection of an adequate implant length is essential to avoid perforation of the maxillary sinus membrane. In this example of an anterior edentulous space, a significant vertical alveolar loss is noted, and as a consequence, limitations to the esthetic result of implant therapy should be carefully assessed and discussed with the patient.

When placing an implant in the correct three-dimensional position, the width of the available bone is often a critical factor. After tooth extraction, nearly 50% of the ridge width is lost within the first year. When considering that in most infected teeth the surrounding bone is already resorbed prior to extraction, it is no surprise that the bone width is often deficient and needs to be addressed. The bone width is not only relevant when selecting the correct implant diameter. It is also important in facilitating a prosthodontically driven implant insertion that ensures the correct position of the final prosthesis. In this example, the CBCT scan demonstrates adequate alveolar ridge width, particularly in relation to the proposed prosthesis. In contrast, the ridge width in this particular case is very deficient and will require a bone augmentation procedure prior to implant placement. Detailed bone assessment is covered in ITI Academy Learning Module on 'Surgical Assessment of the Implant Site.'

In addition to assessing the bone, you should also assess the soft tissues around the potential implant site. Soft tissue examinations should include: The periodontal phenotype, the volume and quantity of soft tissues, and the amount of keratinized tissue.

The periodontal phenotype, also known as biotype, is broadly classified into thick, thin and medium. A thick phenotype is characterized by a flat thick gingiva whereas a thin phenotype is characterized by scalloped thin gingiva. There is a correlation between the phenotype and the thickness of the labial bone in the alveolar socket, with thin phenotype tending to have thin labial bone compared to medium or thick phenotypes. A thick phenotype can be judged to be low-risk when placing implants, since a thick, broad band of attached gingiva is usually resistant to recession. A thick peri-implant mucosa may also mask the color of the implant and of any submucosal metallic components. On the contrary, a thin phenotype is prone to gingival recession. A correctly positioned implant and adequate bone support are important to ensure the long-term success of the prosthesis.

Another variant, the medium phenotype has also been described. It displays some characteristics of a thick phenotype, particularly, the thick attached gingival tissues. In addition, this type also displays characteristics of a thin phenotype, which are long, thin and blunted dental papillae.

A simple clinical technique using a periodontal probe has been recommended to assess the phenotype. When placed in the gingival crevice, a probe that shines through the gingiva signifies a thin phenotype.

As well as assessing the phenotype, the soft tissue has to be examined for any deficiency regarding volume and quantity since this poses a high risk, particularly in the esthetic zone. Soft tissue deficiencies are usually accompanied by an underlying hard tissue deficiency, and therefore, augmentation of both hard and soft tissue may have to be considered.

It is desirable and recommended for implants to be surrounded by keratinized tissue. Although there is no evidence that increasing the width of keratinized tissue improves the long-term prognosis of implants, more plaque and inflammation are found when the width of keratinized mucosa is less than 2 mm.

Implants should be placed in non-infected sites. But neighboring teeth may also have endodontic pathology, or an infected socket might be encountered. Such conditions may compromise the osseointegration of the implant. Therefore, a thorough assessment of the implant site as well as of the adjacent teeth and sites should be carried out, both clinically and radiographically.

Hard and Soft tissue, Key Learning points. Deficiencies in hard and soft tissues should be quantified. Pathosis at the treatment site will interfere with implant osseointegration and should be treated prior to implant placement.

The majority of the assessment tools and techniques used to examine patients for dental implant therapy are the same as the ones used in everyday routine dentistry. In this module, we will provide a brief, general overview of these tools and techniques. A good, thorough visual inspection underpins a successful examination and provides the clinician a snapshot overview of the clinical situation. It can readily inform the clinician of any asymmetry, anomalies, tooth and mucosal color, texture, ridge deformities, and pathoses. Palpation of the site should be carried out to assess any lumps, bumps and relevant anatomical structures. Percussion of the affected and adjacent teeth should be carried out to aid the diagnosis. Pulp vitality should usually be checked with more than one sensibility test. This includes an electronic pulp test and application of heat and cold. As usual, periodontal health is best assessed by probing the gingival sulcus and measuring any attachment loss.

Only after a thorough clinical examination has been performed, can appropriate radiographs be considered to gain further information of the treatment site. Intraoral radiographs, dental panoramic or low-dose cone-beam computed tomograms are most appropriate. The intraoral examination is often inadequate for a full assessment, particularly of any occlusal issues in the posterior regions of the mouth. These can be better examined using articulated study casts. As discussed earlier in the module, a diagnostic wax-up is an invaluable aid when assessing and planning replacement of teeth. Remember, implant treatment should be prosthodontically driven and, as such, a diagnostic wax-up will make it possible to determine the ideal tooth position at a very early stage in treatment. In some cases, a denture tooth set-up is more appropriate. A diagnostic wax-up can be visually shown to a patient, whereas a denture tooth set-up can also be tried inside the mouth, allowing both patient and clinician a much better perspective of the planned treatment.

Assessment tools and techniques, Key Learning Points: A systematic examination of the treatment site should be carried out prior to planning and executing the implant treatment. The majority of assessment tools and techniques are the same as used in everyday dentistry.

"Site-Specific Clinical Examinations", Module Summary: For a successful treatment outcome, a comprehensive examination is mandatory to anticipate and prevent any complications. Examination of the treatment site should include a thorough assessment of the restorative space and characteristics, anatomical factors, hard and soft tissue examination, and pathoses. The tools and techniques for basic assessment are the same as used in everyday dental practice.