8: Immediate provisionalization of implant restorations

Immediate provisionalization of implant restorations

image Additional illustrations can be found on the companion website at www.blockdentalimplantsurgery.com

Patients who receive implants may be candidates for immediate provisionalization at the time of implant placement. Patients request and desire replacement of the missing tooth or teeth as efficiently as possible. Immediate provisionalization of an implant with a toothlike restoration, even though out of occlusion, is well accepted by patients. Patients do not like removable temporary restorations. Patient-driven implant care demands that clinicians consider immediate provisionalization as often as possible. Provisional options when removing a tooth include:

1. A tooth-borne prosthesis with the crown of the tooth placed within a clear acrylic vacuum-form

2. A removable prosthesis, commonly termed a “flipper”

3. A pontic placed on orthodontics appliances

4. A provisional crown bonded to the adjacent teeth. This is performed often a few weeks after implant surgery to avoid disturbance of the surgical site.

5. A fixed, implant-borne prosthesis delivered either within hours of the surgery or within a few days. When considering each patient’s specific needs and desires, an immediate provisional prosthesis placed at the time of implant placement is an ideal solution for many patients. Compliance must be excellent. The patient needs to understand that the single-tooth or multitooth provisional prosthesis is not intended for occlusion, only to shape soft tissue and for esthetics.

Methods for immediate provisionalization of single-tooth implant restorations

The provisional prosthesis provides a reliable method for developing the soft tissue site of single-tooth restorations and facilitates efficient fabrication of the final restoration. The restorative dentist can fabricate the provisional restoration at chairside, before implant placement, or in the laboratory.

• Preoperative laboratory preparation of abutment and provisional crown. This technique minimizes chairside time for the restorative dentist. From simple impressions, an implant analog is placed into the patient’s model, an abutment is prepared, and a provisional crown is made in the laboratory. At the time of implant placement, the abutment and the provisional crown are placed by the surgeon and modified by the restorative dentist if necessary. Contacts and occlusion may need to be adjusted at chairside (Figures 8-1 and 8-2).

• Chairside abutment preparation and fabrication of a provisional crown. This technique requires the abutment to be minimally prepared at implant placement. This requires the surgeon to perform the adjustment, which can be further refined by the restorative dentist. The provisional crown is fabricated by relining a hollow shell. The patient will need to see the implant team and have closely coordinated appointments. The disadvantage of this method is the relining part of the procedure during which the reline material can be forced into the surgical site and compromise the surgical result. If the temporary abutment can be removed easily, then the adjustments and refining of the provisional crown can be performed out of the mouth. This method is not recommended because better options may be available.

• Chairside fabrication of a provisional crown using a stock abutment

• The surgeon and restorative dentist will plan this procedure to be performed on the same day as surgery. Pre-extraction impressions are made and duplicated. One set is used to fabricate a vacuum form, which can be used to hold the extracted tooth’s crown if for some unanticipated reason an abutment and provisional crown cannot be immediately fabricated. This is “plan B” and ensures that the patient will leave the clinic with a tooth in place, which is critical in the esthetic zone. The second cast has the crown on the tooth to be extracted removed from the cast. A denture tooth of appropriate form and shade is wax retained in proper position. An alginate of this setup is made and a stone model poured. A second vacuum form is made. The denture tooth is trimmed to leave the facial aspect as a “shell” or “facing.” The vacuum form is trimmed to hold the denture tooth facing in position when luting it to the abutment after implant and abutment placement (Figure 8-3; see the companion site for the complete case).

• Transfer impression (“indexing”) of implant or abutment for laboratory fabrication of provisional prosthesis, with placement in patient’s mouth within hours or days. At implant placement, an index can be made to allow for a provisional crown to be made in the laboratory. A conventional implant transfer coping can be used or an index can be made using the implant’s driving mount. In these indexing methods, the crown is fabricated out of the mouth and adjusted slightly when placed over the abutment. The impression can be given to the restorative dentist or laboratory for fabrication of the provisional crown, which is placed as soon as it is completed by the laboratory (Figure 8-4).

General considerations

Careful patient and site selection result in successful implant integration and decreased failure. Literature review indicates that single-tooth restorations with a delayed approach, which allows integration of the implant before the final restoration is placed, have a success rate of 94% to 100%, depending on specific implant protocols and the nature of the implant site.1-4

Criteria associated with success using immediate provisionalization include the following:

1. Sufficient bone height, width, and density for stability of the implant at placement. The choice of implant length and width involves considerations similar to those used for implants in a two-stage method. A satisfactory implant insertion torque of or a radiofrequency index greater than 60 are the deciding factors that indicate that implant stability is sufficient for immediate provisionalization.

2. Sufficient mesial-distal, buccal-lingual, and interocclusal space for placement of an anatomic restoration. If the opposing occlusion interferes with the provisional restoration, a two-stage technique is used rather than the immediate provisionalization method.

3. Sufficient vertical dimension stability with occlusal stops to prevent occlusal loading of the provisional restoration

4. The patient should agree to limit chewing to only the softest of foods, preferably liquids, for up to 8 weeks. Patients with excessive parafunctional habits are not provisionally reconstructed.

Preoperative laboratory preparation of abutment and provisional crown

After the patient has been confirmed as a candidate for immediate provisionalization, a preoperative phase precedes implant placement. Cone-beam scans indicate that there is sufficient bone available for ideal implant placement. Mandibular and maxillary impressions are made, the preoperative laboratory phase is completed, and the patient is scheduled for surgery. At the time of implant placement surgery, the surgeon should have the abutment, retaining screw, provisional crown, and models with the analog in place (see Figures 8-1 and 8-2).

Laboratory technique

The preoperative laboratory-based technique is similar for any single-tooth restoration, incisor or molar. The preoperative evaluation of esthetics should follow the same details as for a two-stage procedure. The following technique can be used for immediate extraction sites as well as sites that are edentulous:

1. Impressions are made of the maxilla and mandible, and stone casts are poured.

2. For a site planned for tooth extraction, the tooth is removed from the cast after a model has been poured. The need for a wax-up is determined by the need for esthetic implant positioning. For many situations, a surgical guide stent is not necessary. The position of the implant to be placed is marked, and a pilot hole is drilled in the stone cast. The stone coronal to the analog is shaped to allow an emergence profile for the provisional restoration.

3. The proposed vertical position of the implant analog is marked on the cast, anticipating approximately 3 mm of gingival thickness. In the mandibular area, the thickness of the gingiva may be 2 mm. A cross-section cone-beam radiograph can be used to approximate the position of the bone on the crest. The vertical position of the analog in the model should result in an ideal implant position.

4. A hole is drilled in the model for placement of the analog. The hole must be large enough for passive placement of the analog. The analog is tried in place to confirm proper alignment. Its vertical position should place the top of the implant at the anticipated level of the bone, or 3 mm from the planned gingival margin. The analog is secured in the hole with cyanoacrylate glue, stone, plaster, or light-cured resin. The analog should be consistently positioned with its internal or external retentive feature, such as the flat surface of a hex, facing labially. When the implant team maintains consistent orientation of the analog, the result is less variability of implant orientation, better positioning of the prepared abutment and temporary crown, and better communication among members of the implant team. Implant rotational orientation is not needed for conical internal connections, which rely on abutment torque for rotational stability.

5. A “prepable” abutment is placed in the analog and modified in the laboratory to allow placement of a provisional crown. Another option is to use a try-in kit and choose a final stock abutment that does not need preparation. Many dentists and laboratory technicians make a mistake by preparing the abutment in a manner similar to a tooth preparation. Fixed stock abutments have flat surfaces and small retentive grooves incorporated into their structure, which aids in crown retention. The preparation of the abutment should take into consideration the vertical clearance and modification of the labial or lingual surfaces while retaining much of the retentive aspects of the abutment. An abutment preparation that looks like a tooth prep is not recommended. If the provisional crown will be milled, then the margin shoulder and rounded contours of the abutment preparation are made to be consistent with the needs of a milled crown restoration.

6. The abutment margins should be at the level of the gingiva to avoid deep subgingival margins and to allow ease of cleaning after the implant and provisional crown have been placed. With the use of stock abutments and machined caps, the margins can be more subgingival.

Cementation methods must be performed to avoid subgingival cement excess. A duplicate of the abutment can be made with impression material. The crown has cement placed within it and then placed onto the duplicated abutment out of the mouth. Excess cement is then removed. When placed into the mouth, excess cement will not be expressed into the subgingival sulcus. Screw retention also avoids cement in the subgingival region. The use of deep crown margin placement allows for subgingival contour development by the crown and not the abutment, which may be easier and more predictable.

7. Some feature should identify the labial surface of the prepared abutment, such as the flat surface of the abutment or a dot or groove placed into the abutment’s surface. This allows accurate orientation of the abutment at surgery. The prepared fixed abutment should be left with a rough surface to allow retention of the abutment to the provisional crown with temporary cement. The abutment preparation may result in a shorter abutment than the final abutment to allow 2 mm of interocclusal space between the provisional crown and the opposing restoration. These crowns are provisional and are not placed in occlusion. Typically, 2 mm of interocclusal space is required.

8. After the abutment has been prepared or chosen from a stock selection, either a hollow denture tooth or a hollow-shell crown is relined over the abutment using the opposing model. The provisional crown is adjusted to prevent occlusion. It is useful to leave 0.5 mm of space at the mesial and distal marginal ridges to allow surgical flexibility at the time of the placement and to prevent micromotion on the implant caused by movement of the adjacent teeth. The provisional crown margins are smoothed and polished to optimize the soft tissue response.

9. A hole can be made in the occlusal aspect of the provisional crown to allow access to the retaining screw that secures the abutment to the implant. In addition, this gives the restorative dentist the option of taking an impression of the provisional crown to avoid the use of transfer copings. The abutment retaining screw is removed, and the abutment and provisional crown are removed as one piece. The abutment and crown are placed as one unit onto an analog of the appropriate implant system. This is then placed in the impression, which is poured in stone. The transfer of the implant and the subgingival sulcus is very accurate and eliminates the need for a transfer coping and placement of resin into the gingival sulcus.

Surgical procedure

At the time of implant placement, the surgeon will have the prepared provisional abutment, the provisional crown, and the screw to retain the abutment into the implant. It is useful for the surgeon also to have the model of the analog in place to help guide implant placement and orientation.

Extraction and immediate provisionalization of a central incisor. 

​Extraction and immediate provisionalization are performed as often as possible. The patient must have intact labial bone, no active drainage or exudate, and an occlusion that will allow the provisional crown to be placed out of occlusion. If the occlusion is tight or deep anteriorly, the provisional crown must be shortened, which may result in poor, unacceptable esthetics. In those situations, an anatomic custom-shaped or stock healing abutment should be used at the level of the gingival margin to maintain the level of the facial gingival margin.

The patient in Figure 8-2 has an excellent prognosis for success because she has intact thick labial bone, relatively thick gingiva, square teeth with the interproximal contact close to the bone crest, and an occlusion that allows 1 mm of shortening of the provisional without esthetic compromise. The expected success rate is similar to that for placing implants into edentulous bone.

Incisions are limited to the sulcus surrounding the tooth with no vertical incisions and no periosteal reflection. The sulcular tissue is conservatively elevated to only expose the interface of the tooth with the bone. The tooth is separated from the bone by creating a trough between the bone and tooth using a water-cooled laser, periotome type instruments, or a piezosurgery device with a periotome-shaped tip. After the tooth has been removed, the implant site is prepared. It is critical to carefully remove the tooth with preservation of the intact yet thin labial bone!

The implant preparation procedure starts with a small round or sharp-tipped bur on the palatal slope of the extraction site. This initial hole is located where the most lingual aspect of the implant is planned. The succeeding series of drills tend to bounce off of the dense palatal bone since the labial aspect of the site has minimal dense bone secondary to the extraction site (Figure 8-5). When completed, the central axis of the implant will be slightly labial to the initial round drill hole made in the palatal slope of the extraction socket. If this is not considered, then the implant will be placed too far labial, resulting in compromise of the restoration and compromise of the labial bone with resorption, gingival recession, and an unhappy patient.

The definitive implant site is developed using the normal sequence of drills. The implant site can be tapped to form threads if the bone is dense. The implant is placed with careful guidance to prevent misalignment. The depth, angulation, and position of the implant should be ideal considering the final crown design. The gingival margin of the planned restoration is used for depth management with the implant usually 3 to 4 mm apical to the facial soft tissue margin.

After the implant is placed, it can be indexed if this is the clinical plan. The index can be made using the driver mount or impression copings. The surgeon should be careful to avoid impression material within the surgical site. Bite registration material is very useful to take the index.

The abutment is placed and screw retained to the implant. The provisional crown is placed and adjusted using the technique of choice.

Incision design to facilitate ideal soft tissue. 

​Patients who are missing anterior maxillary teeth or those who had teeth removed and had significant bone defects may have had augmentation of the site before implant placement. In patients who have had prior ridge augmentation, the surgeon may decide to place an implant without raising the soft tissue over or labial to the augmentation. The hesitancy to flap the soft tissue over the previously placed graft is based on the possibility of raising a part of the graft with the flap, decreasing the vascularization of the graft from overlying periosteum, or a desire to place an implant early during the healing period before mature bone formation to the periphery of the augmentation. The augmentation may also have resulted in beautiful thick attached tissue and ridge form, which is desirable to maintain and not change for the final result, without compromise from additional surgical invasion.

Implant placement at that time should not compromise the excellent soft tissue and ridge profile gained from the reconstruction efforts. Incision and flap design should take into consideration avoidance of reflection of the labial gingiva, with the incision shaped to curve around the labial aspect of the abutment to be placed. Palatal tissue can be reflected or the computed tomography (CT) guidance can avoid flaps, leaving the labial tissue without violation.

After the topical anesthetic ointment is applied, local anesthetic is infiltrated into the vestibule and in the palate. Hydropic dissection of the labial gingiva should be avoided. A 30-gauge needle is used to sound the bone through the labial and palatal gingiva to “visualize” the bone without tissue reflection. The use of preoperative cone-beam images helps define the underlying bone anatomy with less need for direct visualization.

After a satisfactory time has elapsed, a scalpel or gingivectomy trephine is used to remove a circle of gingiva exactly where the implant is to be positioned. If necessary, small palatally directed vertical releasing incisions can be made to directly examine the palatal aspect of the ridge. The incision on the crest with the palatal releasing incisions appears “omega” shaped.

After placement, the labial surface of the implant should be approximately 2 mm palatal to a line drawn from the labial surfaces of the adjacent teeth. The 2-mm distance allows development of the proper emergence of the final crown from the gingiva. If the implant is placed too far labially, the gingiva migrates superiorly and eliminates the possibility of an esthetic final restoration. Location of the crestal incision initiates the accurate positioning of the implant.

If the surgeon is certain that sufficient bone width is available for implant placement, the implant site can be prepared through the gingival hole without elevation of a flap (see Figure 8-1). The implant site is prepared using the standard series of drills for implant placement. Attention must be paid to positioning the implant vertically 3 mm apical to the planned gingival margin. The implant should be rotated to match the analog in the model. When a flapless approach is used, the implant driver mount is used to place the implant at the correct depth and to orient it correctly.

When a minimal tissue flap is indicated to ensure correct implant placement in a thinner ridge, a small periosteal elevator (e.g., Hirschfeld #20) can be used to raise a full-thickness flap carefully halfway around the adjacent teeth without tearing the gingiva on the margin of the adjacent teeth. No vertical incisions are necessary. After palatal tissue reflection, the implant site is exposed, and if necessary, the small periosteal elevator can be slid under the labial periosteum over the labial bone to confirm its inclination and the presence of undercuts.

After the bone has been exposed, a round bur is used to mark the site for the implant. This marking must be precise because all drills follow its location. In single-tooth sites, the implant is placed in the middle of the edentulous site equidistant from the adjacent teeth. The center of the implant site should take into account the implant’s final diameter to place the implant definitively, avoiding labial malpositioning. For molars, the center of the implant should allow it to be positioned under the working cusp or within the central fossa of the planned restoration. Similar to anterior cases, the labial surface of the implant should be 2 mm lingual or palatal to the eventual position of the labial surface of the restoration to allow for emergence of the crown and ideal contours.

After the round bur mark has been made, the drilling sequence is followed. Guide pins are placed after the first drilling to confirm that the implant is properly positioned and angled. Modifications are easily made, using the round bur again, by redrilling the pilot hole if necessary.

The implant preparation is completed. When the consecutive series of drills is used, guide pins should be placed to confirm perfect implant placement. The surgeon should perpendicularly orient his or her eyes to confirm that the implant has been placed midway between the teeth and angled perfectly.

The implant is placed with the orientation of the internal or external retentive features matching the orientation of the analog in the model if this method was chosen. The implant should be vertically positioned within the bone depending on the esthetic plan. Primary implant stability must be achieved.

During preparation of the implant site, the prosthetic parts should be soaking in a sterilizing solution. The abutment, provisional crown, and abutment retaining screw are placed in a bowl of povidone–iodine solution. When the implant has been placed, the parts are removed from the solution and rinsed with sterile saline.

The abutment should be placed passively without interferences from soft or hard tissue. Bony interferences must be removed to allow passive placement of the abutment into the implant. If the abutment is not placed passively, excessive pressure can be transferred to the threads, increasing the chance of implant failure. The interocclusal distance is confirmed at this time. If the abutment has not been shortened sufficiently on the model or if the implant is placed more superficially than planned, the abutment may have to be adjusted with a high-speed drill out of the mouth, and the corresponding provisional crown may need relining at the time of insertion. With accurate model preparation, the incidence of abutment modification is less than 5%.

The abutment screw is hand tightened rather than torqued because it is difficult to place countertorque pressure on the abutments while a torque procedure is performed. The provisional crown is tried in position. The contacts are adjusted as necessary, and occlusal clearance in all jaw movements is confirmed. The crown is cemented after a small piece of retrievable material (e.g., cotton, Teflon tape, other soft material) has been placed into the abutment to protect the screw from becoming clogged with temporary cement. After the provisional crown has been cemented and the cement has been cleaned from the margins, the gingiva is sutured if necessary. The KG tissue previously on the crest should be repositioned on the labial surface of the provisional crown.

Chairside abutment preparation and fabrication of a provisional crown

With the use of new high-speed drills and gentle technique, abutments can be adjusted in the mouth. This reduces implant dentistry to conventional dentistry, without the need for transfer copings and other parts. The surgeon places the implant and the abutment or a one-piece implant with the abutment incorporated into its body. The surgeon or restorative dentist performs a simple reduction in height and labial or lingual contouring as necessary, and then a hollow shell is relined (see Figures 8-1 and 8-2).

The use of high-speed, new diamond or carbide burs with copious irrigation and gentle pressures does not transmit excessive heat to the implant and surrounding bone. Thus, preparation of the abutment or supragingival portion of a one-piece implant is acceptable if properly performed. The advantage is simple, routine dentistry techniques similar to crown preparations; however, the disadvantage is the need for careful coordination of the appointments for both offices and gentle technique for abutment modification. An additional disadvantage is the use of relining materials in fresh surgical sites, where the material can be left under the soft tissues. This method is not indicated when removing a tooth and placing an implant because most likely a graft will have been placed in spaces between the implant and the remaining bone.

This protocol requires minimal preoperative preparation. The abutment is selected before implant placement, taking into consideration the estimated thickness of the gingival margin and the interocclusal distance. If the abutment is carefully selected, minimal modification is necessary. The provisional crown must be chosen before implant placement, taking into consideration the shade of the adjacent teeth. The surgical technique for placing the implant is similar to that described earlier.

Placing the final abutment for fabrication of a provisional crown

The concept in this approach is for the surgeon to place the implant and immediately place the final abutment. The final abutment requires a coping that provides excellent marginal adaptation to the abutment ensuring healthy gingival reactions. A denture tooth is hollowed and luted to the coping using light-cured composite. The tooth with plastic coping is removed, and additional composite is added outside of the mouth by the dentist. The cervical contour of the crown is slightly undercontoured to allow for coronal drape of the gingiva. An overcontoured gingival margin will push the tissue apically, which is not ideal. The subgingival portion is contoured to be concave, maximizing the soft tissue thickness, which over time will scar, contract, and become resistant to apical migration. After contacts and occlusion are verified, the provisional crown is carefully temporarily cemented.

Why do this? Traditional steps include implant placement, placement of a cover screw or healing abutment, removal of the healing abutment for a subgingival implant-level impression, replacement of the healing abutment, placement of an abutment and a provisional crown to form the soft tissue, and then a repeat of this sequence for the final crown. By placing the final abutment at the time of implant placement, the only future procedures needed are an abutment-level impression and delivery of the final crown. The immediate provisional crown with anatomic subgingival form develops the tissues, and thus the final crown can be delivered with minimal chair time and elimination of trauma from repeated abutment removals.

Case example

The patient in Figure 8-3 fractured her central incisor at the level of the alveolar crest. The restorative dentist thought that the long-term prognosis for post and core with crown lengthening would be lower than an implant restoration. The patient desired a fixed provisional restoration.

Preoperative imaging showed sufficient bone for primary stability of the implant into the bone along the palatal aspect of the tooth after the tooth was removed. The preoperative workup for the patient included:

Surgical method. 

​After local anesthesia was infiltrated, a sulcular incision was made and a small flap elevated to visualize the tooth bone interface. For this patient, a water-cooled laser was used to create a trough between the bone and tooth. The tooth was subluxed and removed after the crown had been removed.

A round bur was placed along the palatal slope of the extraction site, and an entry site was created for the subsequent twist drill (see Figure 8-5). The twist drill was used to length with its axis slightly palatal to the planned incisor edge. The final drill was used to length. The slow-speed bone-shaping drill was used to shape the osteotomy site and the implant (Ankylos; Dentsply Implants, Waltham, MA) placed. The shoulder of the implant was countersunk 1 mm apical to the crestal bone.

A try-in kit was used to choose the final abutment. The final abutment was chosen with 2 mm of occlusal clearance with its emergence palatal to the incisive edge. If the angulation of the implant is emerging on the incisive edge, a 15-degree angled abutment should be placed to have the retaining screw slightly/>

Jan 5, 2015 | Posted by in Implantology | Comments Off on 8: Immediate provisionalization of implant restorations
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