Successful implant treatment requires a prosthodontically driven implant plan to determine the ideal implant position. The implant position should facilitate the placement of an optimal definitive prosthesis which fulfils both functional and esthetic demands and mimics the natural dentition.

By using additional diagnostic investigations, site-specific surgical and prosthodontic requirements can be identified and assessed. This helps to minimize the risk of complications and failures following implant treatment.

After completing this ITI Academy Module, you should be able to recognise indications for additional diagnostic investigation in implant treatment planning and describe different additional diagnostic investigations.

Diagnostic information from clinical and radiographic examinations may not be sufficient to allow a full case assessment. Additional diagnostic investigations may be required to achieve complete assessment and diagnoses. Cases classified as Advanced or Complex according to the ITI SAC Classification are likely to require additional diagnostic investigations. These additional investigations would be aimed at (3D) analysis of prosthodontic and surgical requirements. They could also be aimed at establishing the need for a multi-disciplinary approach, for example with orthodontic input.

Implant placement in the esthetic zone will almost always require additional diagnostic investigations. Treatments in this area are classified as advanced or complex according to the SAC classification and consequently impose an increased risk of complications.

In this patient case the upper right central incisor is missing and the upper left central incisor is due for extraction. A diagnostic wax-up will assist the esthetic planning and address related factors identified in the Esthetic Risk Assessment. The wax-up will make it possible to visualize the final prosthetic tooth size of both central incisors. For example, the mesio-distal width of the upper right central incisor space is less than the width of the existing crown of the upper left central incisor space. A wax-up of the future implant crowns could therefore reveal an emergence of a possible minor midline discrepancy to the left.

Analysis of the patient's existing occlusal scheme is particularly relevant to assessing the risk of technical complications for planned implant supported prostheses. In this clinical example the lower right second premolar is missing and the patient would like it replaced with an implant supported crown. Visual inspection immediately reveals the presence of wear facets on adjacent teeth that can be attributed to parafunction. There is also over-eruption of the opposing upper right second premolar. An occlusal analysis on mounted study casts together with diagnostic wax-up of lower right second premolar is required to assess the possibilities of achieving recommended dimensions and occlusal scheme for an implant supported prosthesis.

Analysis of anatomical requirement can also be aimed at assessing the loss of hard and soft tissue volume in an edentulous area. This can be assessed by evaluating the ideal position of the teeth as seen in this wax-up in relation to the anatomical situation. In this extended anterior span situation the volume of pink wax is an indicator of the significant discrepancy between the desired tooth positions and the underlying edentulous ridge. This discrepancy may pose difficulties to achieving an optimal esthetic and functional result with a fixed dental prosthesis.

The upper left first molar has been removed with a minimally traumatic extraction technique. The preservation of the soft and hard tissue appears to be favorable. Equally, the prosthodontic requirements to esthetic and functional replacement of the upper left first molar appear straightforward. Additional radiographic imaging, however, is required for assessment of the bone dimensions available below the maxillary sinus for implant placement.

Combined analysis of prosthodontic and surgical requirements is likely to become increasingly necessary the more teeth are planned for replacement. The patient in this example would like to convert from a removable to a fixed dental prosthesis to replace missing maxillary teeth. The fixed dental prosthesis will be replacing both anterior and posterior teeth and the patient is missing posterior mandibular teeth on the left side as well. The indications for additional diagnostic investigations include number of teeth to be replaced, esthetics and phonetics of planned tooth arrangement, evaluation of extra-oral facial support, design of occlusal scheme and need for hard and/ or soft tissue augmentation procedures required for a fixed rehabilitation based on implant supported FDPs.

Additional diagnostic investigations could also apply to establishing the need for a multidisciplinary approach. In this clinical case the upper left central incisor is due for replacement with an implant supported crown. It is clear, however, that there is crowding in the arch. In order to avoid an esthetic and functional compromise and with a view to a longer term stable outcome, supplementary treatments, like orthodontic interventions, might be necessary to re-establish sufficient space.

Indications for Additional Diagnostic Investigations, Key Learning Points: Additional diagnostic investigation may be required when clinical examination and preliminary investigations are insufficient to arrive at a proper diagnosis of the underlying condition, in Advanced and Complex cases, in analysis of prosthodontic and surgical requirements, and in establishing a need for multidisciplinary treatment approach.

Additional diagnostic investigations include: 1. Photography and videography, 2. Digital simulation and smile design, 3. Articulated study casts, 4. Diagnostic wax- and set-up, both analog and digital, and 5. Radiographic imaging.

Photography and videography are key elements in supplying additional visual diagnostic information for esthetic rehabilitation. It allows the clinician to record and evaluate together with the patient information regarding the facial, gingival and dental esthetics. Since implant treatment involves a multidisciplinary team, it also enables efficient communication between the team members by exchanging photos and videos.

The facial analysis includes an assessment of parallelism between the upper horizontal line and the commissural line, which are perpendicular to the facial midline. Any disharmony in these lines can be identified using photography. Such disharmonies may have a profound effect on the occlusal plane of the implant prosthesis planned for the esthetic zone. The proportions of the facial thirds have to be assessed, as a decreased lower facial third may indicate a decrease in Vertical Dimension of Occlusion or VDO. A decrease will have to be further investigated to decide if the planned implant prosthesis may be used to achieve an increase in the VDO.

A smile line is classified as being low, medium or high. It is assessed by taking photos at rest and during smiling and by evaluating the incisal edge position in relation to the upper lip. A patient with a high smile line shows a component of the alveolar ridge during smiling, which increases the risk of esthetic complications when implants are placed in the esthetic zone. The width of smile should also be evaluated and recorded photographically. Some patients have a narrow smile and do not show a large component of the posterior teeth and buccal corridor upon smiling. Patients who present with a large buccal corridor will usually display all of the posterior teeth during smile which increases the extent of the esthetic area.

When the upper anterior teeth have been lost it can be difficult to determine appropriate shapes, arrangement and dimensions for the replacement teeth. Old photographs from a time when the patient still had the upper anterior teeth can then be an invaluable help. To be used as a guide to the original dimensions of the teeth, the patient needs to be facing and looking directly at the camera in the old photo and smile widely to display the upper anterior teeth. The width of the original central incisors in real life can be calculated by using the equation shown here. By facing and looking directly at the camera the inter-pupillary distance can be measured in the photo. This distance does not change after the age of 20. By smiling and displaying the upper anterior teeth the combined width of the two central incisors in the photo can be measured too. The patient's inter-pupillary distance in real life is measured. The combined width of the original central incisors can then be calculated by entering the measurements into the equation. Finally the combined width can be halved to get the width of the individual central incisor.

The tooth characteristics of the prosthetic reconstruction should correlate with those in the remaining dentition. By using intra-oral photography, the required tooth shape, size and characteristics of the planned prosthesis can be evaluated. It is also a means of confirming the planned esthetics with the patient and for use in communication with the technician when preparing the diagnostic information needed for the temporary prosthesis.

With the increasing access to videography, not least via smartphones, video sequences can be easily recorded. These allow dynamic visual and audial assessment of the patient. This can be very helpful for the purposes of observing and discussing esthetics, phonetics, function as well as facial support and movement during talking, smiling and other relevant activities. Videos also facilitate discussion of improvement and changes between clinician and patient.

The digital simulation and smile design concept is based upon incorporating the patient's facial and dental proportions utilizing diagnostic planning software. Digital photographs and videos are utilized in the software to create the ideal smile design for each individual patient, integrating the patient's own teeth, gingiva, lips and smile. The optimal shape and proportions of teeth can then be digitally manipulated to create the perfect smile.

The digital simulation and smile design greatly improves communication between patient and clinician and provides the patient with the confidence to be part of the treatment planning phase and to share their opinion about the ultimate smile design. The patient can provide feedback to the clinician as to whether or not they like or dislike the smile design. From the clinician's point of view, the patient can be made aware of limitations of unrealistic esthetic expectations before commencement of treatment. It also facilitates effective communication between the clinician and technician.

Articulated diagnostic study casts may reveal additional diagnostic information that may not be readily identified on clinical examination. Study casts also allow assessment of the clinical situation away from the patient. Several aspects of the dentition can be identified: The static occlusion can be evaluated. The dynamic occlusion can be assessed in terms of guidance and possible interferences including the impact they might have on the planned implant prosthesis. Wear facets can be studied in more detail as well as the extent of edentulous areas. The intermaxillary distance and the available prosthetic space for crown placement can also be assessed. The accuracy of the occlusal plane can be identified. If a correction is required, it can be planned and corrected before implant treatment. Morphological defects can also be identified and evaluated by using articulated diagnostic study casts.

Study casts need to be precise, and therefore require accurate impressions that are free of drags and bubbles. The study casts are transferred to a semi-adjustable articulator with a facebow recording. Correct and accurate bite registration records are required to mount the study casts on the articulator.

When teeth are missing, a diagnostic wax-up or set-up should be made. The diagnostic wax-up should anticipate the final prosthesis including the surrounding hard and soft tissue and recreate the harmony between the white and pink esthetics. Thereby, diagnostic wax-ups optimize surgical planning and the prosthetic result.

The diagnostic wax-up is used to determine the number and positions of teeth to be replaced and their relationship with the opposing dentition. The occlusion should be designed to minimize the non-axial loading on the planned implants. The positions and number of implants in the edentulous areas can then be planned.

The amount of hard and soft tissue change in the edentulous area can also be assessed by evaluating the ideal position of the teeth in the wax-up in relation to the anatomical situation. As a general guide If the ideal crown wax-up ends at soft tissue level, only minimal change has occurred.

For larger discrepancies between the crown wax-up and the alveolar ridge, the clinician should consider bone and/or soft tissue augmentation. Alternatively, an artificial pink component of the definitive prosthesis can be anticipated. In cases where there is significant hard and soft tissue loss, the diagnostic wax up is a useful means for communicating and discussing treatment needs and potential esthetic outcomes with the patient.

The ideal position of the teeth and hence the correct 3-D positioning of the implants needs to be evaluated as part of the diagnostic process. Diagnostic wax ups are an indispensable tool for this. Once the ideal positions of the teeth have been established, a radiographic template incorporating radiographic markers like gutta percha or metal inserts can be derived from the diagnostic wax-up. A Cone Beam Computed Tomography or CBCT can be taken with the radiographic template in the patient's mouth. This will in turn be used for three-dimensional planning for implant placement, often using digital planning software.

In this clinical case the initial wax-up indicated a significant discrepancy between the desired tooth positions and the underlying contours of the hard and soft tissues. Staged bone augmentation was carried out and a surgical template derived from the tooth positions in the original wax-up is used during the subsequent implant placement to determine their positions. The temporary prosthesis is also derived from the tooth positions on the original wax-up but the bone augmentation has eliminated the need for the soft tissue portion of the wax-up.

The diagnostic work-up can also be achieved through digital planning. Based on an intraoral digital impression or scanning of analog study models, the replacement prosthesis can be designed digitally according to desired parameters. The examples seen here illustrate the three-dimensional scope for modelling the prosthesis contours. This includes the dimensions of the prostheses as well as its mucosal emergence profile and occlusal scheme.

Radiographic templates which incorporate radiopaque teeth can provide further diagnostic information that can greatly assist planning for the correct implant position. In this example, radiopaque teeth have been incorporated into the radiographic template. A sagittal view at one of the tooth sites illustrates the relationship between the edentulous ridge and the radiopaque outline of tooth in the radiographic template. From this, the correct axis of the implant in the ridge can be readily identified.

Radiographic imaging is an essential tool for dental implant planning and is part of the additional diagnostic investigations. With appropriate radiographic techniques, the residual bone volume and the orientation of the residual alveolar ridge in relation to the ideal alignment of implants can be determined. Local anatomical structures and pathologic boundaries that may limit implant placement can also be identified. For this maxillary central incisor site a 2D periapical film shows the bone crest and the nasopalatine canal. The adjacent teeth and their endodontic status can also be seen. The 3D Cone Beam Computed Tomograph or CBCT for short further shows the edentulous ridge in cross section, clearly illustrating the location of the nasopalatine canal orofacially. The Clinician should determine most appropriate radiographic investigation to utilize based on the clinical conditions of the site. This could be either 2D imaging or 3D imaging or as in this case, where the diagnostic information complement one another.

Radiographic imaging can be combined with preoperative digital study casts to plan for a prosthetically driven implant placement, following a complete digital pathway. Anatomical structures can be identified on digital diagnostic study casts, and with the digitally designed future replacement prosthesis, the ideal implant placement positions and dimensions can be planned. A digitally designed implant drill guide can be manufactured.

Additional Diagnostic Investigations, Key Learning Points: Additional diagnostic investigations include extraoral and intraoral photography, videography, mounted diagnostic study casts (either digital or analog), diagnostic wax-up and set-up (either digital or analog) and radiographic imaging. Photography records the facial, gingival and dental esthetics. Videography allows for dynamic esthetic assessment. Analog or digitally created diagnostic study casts allow a thorough assessment of the clinical situation outside the mouth. The analog or digital diagnostic wax-up and set-up assists the clinician in visualizing the desired end result for a prosthodontically driven approach.

Radiographic imaging is an essential tool for dental implant planning. 2D or 3D imaging or a combination of both are a valuable part of additional diagnostic investigations. Diagnostic planning software incorporates radiographic imaging and digitally created future prostheses to create an implant drill guide considering all anatomical limitations and prosthetic considerations following a complete digital pathway.

Module Additional Diagnostic Investigations, Summary: Additional diagnostic investigations are an important step in planning implant treatment in the advanced-to-complex clinical scenarios. These investigations are almost always indicated when planning implant treatment in the esthetic zone. The clinician should remember the concept of a prosthodontically driven treatment plan, where the ideal implant prosthesis is planned before initiating implant placement. Additional diagnostic investigations include extraoral and intraoral photography, videography, analog or digital mounted diagnostic study casts, analog or digital diagnostic wax-up and set-up, and radiographic imaging using radiographic templates and incorporating diagnostic planning software.