DENTAL IMPLANT TREATMENT

By Dr Brenda Baker BDS Hons. (Syd) MSc. Conservative (London) Senior Clinical & Technical Support Consultant Southern Cross Dental

he practice of implant dentistry health and regeneration and the cellular Implants tolerate axial load better than has greatly expanded so that it can reactions to trauma (5) and has been shown lateral load (8). In order to avoid excessive enhance the clinician’s ability to to be associated with more early failures lateral loads on a posterior implant, restore dentitions and improve than in non-diabetic patients (6). desirable occlusal schemes would include Tthe patient’s quality of life. In order to fulfil well-designed immediate anterior guidance the high expectations associated with OSTEOPOROSIS: (9).Implant-supported restorations are more the provision and success of implants, The agents used to treat osteoporosis are vulnerable to occlusal overloading than disciplined meticulous observation and bisphosphonates. Patients receiving i.v natural teeth (10) and any parafunction adherence to certain details are critical. bisphosphonates are at greater risk of should be identified as this will affect the Successful osseointegration must be bisphosphonate-induced osteonecrosis long-term predictability of the implant (11). accomplished with a placement of the but there have been reports of developing The osseous condition of the intended implant to ideally support the proposed osteonecrosis with oral bisphosphonates. implant site is an essential part of the restoration. Implants should be considered Vascular and heart conditions: Heart diagnostic data. The osseous architecture as a prosthetic procedure with a surgical medications for either hypertension or and quality in relation to the contours of component. anticoagulant therapy can complicate initial the proposed dental prosthesis have to be Dental implants are an imperative tool implant surgery. evaluated. for conservative management of single Radiographic reviews should include: missing teeth in an otherwise unrestored SYSTEMIC DISEASE/RADIO/ n volumetric assessment of available dentition and have wider applications with CHEMOTHERAPY: (SEE CHART 1) bone which is best achieved by use both bounded and free-end saddle areas Several local factors can affect implant of CBCT (12). A CBCT image offers as well as the restoration of largely or full success (Table 1) and the one of most careful measurement of mesiodistal, edentulous mouths. The posterior areas of notable being periodontitis. Several reports buccolingual and occlusogingival osseous the mouth, especially the first molars often have shown that periodontal disease dimensions and the topography of the require the replacement of a single tooth (1). increases the chances of periimplantitis (7). edentulous space. n periapical radiographs done with a long- EVALUATION DATA COLLECTION cone paralleling technique (13) are still Successful patient selection depends on the Both the complexity of implant placement important to help evaluate adjacent tooth systemic health of the patient and various and subsequent restoration can be managed connective tissue attachment and bone local factors around the implant site. A by thorough and methodical treatment levels in the anterior maxillary aesthetic detailed and thorough systemic health planning procedures (Chart 1). zone. Radiopaque millimetre grids can review with special emphasis on factors Accompanying perioral and intraoral be superimposed over the film before it is which will influence osseointegration is photographs provide valuable information exposed (14). crucial when assessing implant patients. of local conditions to augment treatment Several key systemic factors will affect the planning and hence provision of successful ACHIEVING SUCCESSFUL success of implant therapy (see Chart 1): implant prostheses. All implant treatment cases should start OUTCOMES: WHAT TO ALCOHOL: with accurate study models taken with a CONSIDER? Regular alcohol consumption can lead facebow and mounted on a semi-/fully- to changes in bony healing which affects adjustable articulator. A. AESTHETICS osseointegration and results in implant Mounted models allow: Aesthetic anterior implant-retained failure (2). n accurate and easy measurement of restorations should involve a smile analysis residual alveolar ridges and interproximal to achieve the most optimal outcome. This is TOBACCO: spaces most easily attained by the use of diagnostic n increases the chance of implant failure n assessment of available interocclusal intraoral photographs of the anterior tooth by more than twice than in non-tobacco space display. users (3). n assessment of space in the implant A smile analysis is done by careful n affects both the initial placement of receptor site evaluation of the pink, white and black implants and the long-term health and n aesthetic analysis components of the smile. stability of the implant as it has a negative n occlusal analysis. Pink aesthetics relates to the examination effect on several types of bone grafting Some single tooth cases can be mounted of the shape of the gingival tissues around which restricts the appropriateness of in the habitual intercuspidation position the gingival margins and edentulous spaces. implant sites (4). and other larger rehabilitation cases White aesthetics relates to the study of particularly when there are changes in the tooth morphology, position and axial DIABETES: vertical dimension need to be mounted in inclination of the clinical crowns within the Affects healing by affecting microvascular centric relation. arch of the aesthetic zone.

24 Implant Dentistry Today

Chart 1

Black aesthetics relates to the embrasure abutment interface to the gingival zenith by using properly contoured abutments and spaces around teeth which aid in the and should be: provisional crowns. An abutment can be framing of the aesthetic zone and express z 3 mm apically displaced from the zenith. placed to allow formation of biologic width the complete tooth shape. z 2 mm palatally displaced from the zenith. along the abutment which will allow proper The majority of unresolved aesthetic This makes sure that there is enough shaping of the peri-implant tissues. problems occur as a result of discrepancies thickness of bone and mucosa to support Typically, the abutment will be concave of the implant dimension and the form of the tissues. If bone is not present except for a convexity on the buccal. In orientation. This is often due to improper at approximately this position from the order to achieve superior aesthetic results, clinical management of peri-implant and gingival zenith, then bone grafting should be provisionalisation of both temporary crowns peri-coronal soft tissue architecture (16). considered for optimal aesthetics. and abutments enables the clinician to Cooper (17) has stated that “dental “Zenith-directed planning” is achieved assess the tissue response and subsequent implant placement can be guided by the using study casts and diagnostic wax- refine the definitive restoration. location of the gingival zenith”. The gingival ups. The proposed crown contour can be Note: The final abutment is a critical zenith is the soft tissue reference point. included in the CBCT image by use of a component in the control of the peri- radiographic template. The final surgical implant mucosal form. What affects the gingival guide will incorporate the location of the zenith? gingival zenith. B. RESTORATIVE SPACE Thus, once the gingival zenith is clearly The amount of space needed varies greatly RELATIVE TISSUE LOCATIONS defined the depth of implant placement can depending on the type of restoration that is The planned gingival zenith should be be well-controlled and optimal aesthetics planned: symmetrical with the contralateral tooth can be achieved. For a single-tooth screw-retained and be in balance with the gingival levels of restoration, a crown can be screwed directly adjacent teeth. A diagnostic wax-up allows PERI-IMPLANT MUCOSAL DESIGN to the implant with 6 mm of space needed the exact assessment of the amount of Predictable aesthetic success is possible from the restorative platform of the implant resorption, enables planning of important if the dentist assesses the connective to the occlusal plane. aesthetic parameters and suggests the ideal tissue attachment at the adjacent teeth. A single cement-retained crown of restorative form. Interproximal papillae depend on adjacent fixed implant-supported needs NB. Interproximal tissue contours of the tooth contours. Using study casts and a about 8 mm of space to accommodate the papillae are supported by adjacent teeth diagnostic wax-up, the relationship between abutment and the prosthesis. An extra 2 connective tissue contacts. the gingival zenith and the existing mucosa mm of distance from the implant/abutment can be evaluated. Tooth form is largely interface is needed to allow formation of the DEPTH OF IMPLANT PLACEMENT defined by the peri-implant soft tissues. biologic width of the abutment. Ideally, for A biologic width forms at the cement-retained prostheses, 8-12 mm of (18). The buccal dimension of the biologic PROSTHETIC MANAGEMENT OF PERI- crown height space is needed. width created at the abutment is about 3 IMPLANT DESIGN Bar-retained restorations may require as mm (19). Once the implant is correctly placed in much as 16-18 mm space from the implant/ The “three/two” rule describes the bone, the control of the peri-implant tissues abutment interface to the planned occlusal relationship in space of the implant/ is improved by enhanced tissue remodelling table so there is enough room for the

Implant Dentistry Today 25 abutment, bar, acrylic and teeth. measured from the ridge crest to the n The anterior/posterior distribution of For simple single-tooth implants, the occlusal plane must be 10 mm or more. implants must be at least 10 mm. The aim “Rules of Six” (20) determine if there is When planning for implant placement, is to have the distal implant in the distal- adequate space for successful implant know the planned position of the most location not impose on the inferior restorations: prosthetic teeth. Plan DOWN from the dental nerve. n 6 mm of inter-radicular space occlusal plane and not UP from the The all-on-four concept requires that n 6 mm of buccolingual osseous dimension osseous crest. posterior teeth beyond the first premolar n 6 mm of minimum implant length n The restorative dimension for any are supported by a cantilever. The aim is to n 6 mm of interocclusal distance for implant prosthesis has 4 key components reduce or eliminate the cantilever by distal prosthetic and component requirements each with its own dimensions: placement of terminal implants. n Less than 6 mm distance from the bone z Transmucosal dimension (biologic crest to the interproximal contact point width) of about 2 mm CONCLUSION for papillary formation z Supramucosal abutment height (0-2 Various considerations apply with patient n “Three/two” rule – zenith planning (see mm ) to allow hygiene selection and implant treatment planning. above) z Framework height 3-5 mm The systemic and oral health of the patient, There are three “rules” for treatment z Acrylic thickness of more than careful intraoral assessment of soft tissue planning for any implant-retained 2 mm and residual supporting tissues and the overdentures or implant-supported fixed Given that there needs to be space planned restoration have to be evaluated. prosthesis called the “Rules of 10” : for location of teeth, frameworks, As much diagnostic information as possible n The inferior/superior dimension of the attachments, retaining abutments (balls, needs to be collected with photographs, mandible must be 10 mm or more. bars, etc) and the biologic width at least various radiographic images and study n The interocclusal (restorative) dimension 15 mm is advised. models with diagnostic wax-ups of the

CASE 1: The dentist requested upper and lower fixed The aim was to restore 16-26 on the for accuracy for the final PFM. The implant-supported telescopic prostheses maxilla and 36-46 on the mandible. If there abutments were to be placed in the with custom-milled abutments. was too much overhang, then only 35-45 mouth, then the acrylic bonnets placed would be restored. over them and then a pick-up impression The dentist requested: to check the accuracy of the model. 1. Please mount upper model using 5. Once the abutments were made, an facebow. acrylic temporary restoration was to be 2. Articulate the upper and lower models fabricated including artificial gingiva to using the clear denture duplicates as a fully replicate the final restoration. These bite. were to be inserted in the mouth and the 3. Make the custom abutments with a aesthetics checked and the bite adjusted. 12 degree taper and milled finish. The 6. Once the provisionals were finally option existed to either mill the wax-up adjusted, the plan was to complete one or the metal. jaw at a time. Fig.1 This preoperative view illustrated the destructive periodontitis evident with significant 4. Duralay bonnets were requested for the Note: The temporary dentures were attachment loss and associated loss of posterior abutments for a pick-up impression included in the case as a guide for aesthetics. support.

Fig. 2a – upper healing caps in situ. Fig. 2b – lower healing caps in situ. Fig. 3 The position and angulation of impression copings is indicated.

Fig. 4 reveals the abutments in situ. Fig. 5 shows occlusal view of abutments. Fig. 6 reveals buccal view of abutments in situ.

Fig. 7 shows occlusal view of abutments. Fig. 8 The completed implant-supported Fig. 9 The final restorations were placed. prostheses were shown to the patient prior to insertion.

26 Implant Dentistry Today proposed prostheses. Adherence to the CASE 2 Rules of 6 and Rules of 10 will allow the A middle-aged gentleman presented with a periodontally compromised dentition with treating clinician to plan for sufficient space inadequate posterior occlusal support. Teeth 41, 42, 31 and 32 were deemed hopeless and for restorations which will be both aesthetic removed. Two implants were placed in the 42/32 regions. Provisionalisation was provided in and achieve longevity. both the lower and upper jaws to evaluate function and aesthetics. Southern Cross Dental would like to thank Dr Lincoln Harris, Queensland who graciously permitted publication of his cases. n

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Fig. 17 Impression copings are shown over Fig. 18 The provisional restoration is shown. implants.

By Dr Brenda Baker BDS Hons. (Syd) MSc. Conservative Dentistry (London) Senior Clinical & Technical Support Consultant Southern Cross Dental

Fig. 19 The lingual view of the provisional restoration is observed.

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