INDIA
INTERNATIONAL
Extraction of single rooted teeth for immediate post extraction implant placement
A single tooth with a root form resistant to removal, such as bulbous tip or a curve, may have to be removed by sectioning the root mesio-distally in the longitudinal plane or bucco lingually if damage to the labial plate is to be prevented. In elevating the sectioned root, care must be taken not to damage the socket or interstitial bone.
a) Extraction with Forceps
During extraction of a tooth, the integrity of the socket must be maintained. Extraction forceps with fine beaks must be used in addition to root elevators. The forceps should be used in a rotation motion and not in bucco-lingual traction while extracting a single rooted tooth. This helps to ensure maintenance of the labial plate. Care must be taken not to damage the labial plate, which is often most fragile in the anterior region.
b) Extraction with periotomes
Periotomes are very fine surgical instruments designed to penetrate the periodontal ligament space when placed and then sever the periodontal fibre attachment and bring out the tooth/root with a wedging effect. It is important to keep in mind that the periotomes be used in only in the mesial or distal sides or to a certain extent on the palatal side, but never on the buccal side. The periotomes can be combined with the forceps once it has been felt that the fibres have been detached to a large extent.
The periotome is placed at the disto-palatal or mesiopalatal line angle within the periodontal ligament space, and controlled pressure is applied in a back-and-forth motion until tooth luxation occurs. It may be placed into the facial socket space for final removal of the intact tooth.
In the case of more complex extractions, an alternative technique includes the use of high-speed diamond rotary instruments under copious irrigation to hollow out the root structure until a thin shell remains. This is collapsed internally with the periotome or thin elevators.
c) Extraction with extractors
Tooth/root can be removed alternatively using instruments called extractors where the tooth to be removed is sectioned at the cemento enamel junction, and a post is threaded into the root using a lever principle. The tooth/root is eventually pulled out in a vertical plane without disturbing the buccal plate.
d) Extraction with piezosurgery (Blus C 2010)
The advent of piezosurgical equipment has made it possible to section the tooth in the least traumatic manner. Vibrating syndesmotomes are brought through the gingival sulcus into the space occupied by the PDL between the root and socket to cut the PDL fibers surrounding the tooth socket up to or greater than 10 mm. Thus, when the roots or teeth are mobilized after severing the most apical fibers, the coronal portion of the socket has not been submitted to a violent “rip.” At this stage, a nearly atraumatic extraction can be achieved. The piezosurgical tips can be used to section the root and then extract the root pieces.
Socket evaluation
After the tooth has been removed, it is important to evaluate integrity of the socket walls. Any deficiency in the socket walls, especially on the buccal wall. Though this would not necessarily compromise osseointegration, but, would however compromise the esthetic outcome of the procedure. After tooth removal, a blunt instrument such as a round ended or ball tipped periodontal probe or curette is used with a very gentle tactile motion on all walls of the socket to check for any perforations and also to confirm that the location of the buccal plate is intact.
A common sequel after extraction of a tooth with labial bone dehiscence is a more apical location of the gingival margin due to loss of cortical bone support. This soft tissue deficit must be corrected to avoid esthetic problems resulting from a final crown length that is not in harmony with the adjacent natural teeth.
2. Implant placement into the extraction socket
While placing an implant into an extraction socket, it has to be placed in line in the anticipated future restorative outcome. The standard drilling procedures have been modified for the placement of implants into the extraction socket. Penetration of palatal wall of extraction socket is done by sharp precision drill which guides the initial preparation of an osteotomy.
Anterior maxillary immediate implant placement situations
In the maxillary anterior region it is important to avoid placing the implant directly into the extraction socket.
The sockets of the maxillary anterior teeth are far buccally placed as compared to the incisal edges. If an implant is placed in line with the apex of the socket, it is quite likely that the implant might get severe buccal angulation and this would compromise the esthetic outcome or perforation of buccal plate may occur which may result in failure of implant.
The axis of the implant must correspond to the incisal edges of the adjacent teeth or be slightly palatal to this landmark.
So, prior to initiation of the drilling, the location of the apex has to be identified using a wide drill/ location indicator and check its location in the bucco- lingual direction.
It is now being recommended that the initial entry point into the socket be made with a more buccal angulation of the drill somewhere in the middle to the apical third of the wall of the socket and straighten the drill slowly bringing it in line with the desired implant angulation.
The next drill will be used to shave some amount of bone at the mouth of the palatal wall.
There are times when the bone at the cervical third of the palatal wall of the socket resists the proper angulation of the bur. So it is preferred to trim this part of the socket wall so that the proper angulation can be achieved.
Sequential drilling has to be continued as per the manufacturer’s guidelines to complete the preparation of the osteotomy.
Implant placement in the anterior maxilla
Bucco-lingual positioning
The implant placement follows the same steps as the drilling protocol wherein the implant is initially locked in buccal angulation and then straightened till its final positioning with respect to the cervico incisal positioning of the implant.
Apico coronal positioning
While placing the implant in the anterior maxilla, or the esthetic zone, the implant head should be a minimum of 3 mm apical to an imaginary line joining the buccal cemento–enamel junctions of the adjacent teeth or at least 1 mm apical to the buccal alveolar crestal of the socket and interproximal bone. This will assure a proper implant emergence profile and facilitate proper implant restoration.
Immediate implant placement in posterior teeth
While immediate post extraction implant placement is not routinely carried out usually due to the lack of adequate interradicular bone and the doubt in achieving primary stability. In case where the immediate post extraction implant placement is carried out, care has to be taken that the roots of the multirooted teeth are removed by sectioning and the site has been prepared in the interradicular bone and not in the mesial or distal of the socket.
Socket preservation (Becker W 2008)
Socket preservation refers to the placement of various implantable materials within extraction sockets to maintain the socket anatomy.
There is inconclusive evidence that this procedure maintains the original socket dimensions. In contrast, evidence exists that the placement of foreign materials into extraction sockets may interfere with normal bone formation (Becker W, Becker BE, Polizzi G, Bergstrom, 1994; 1998)
There is evidence that resorbable barriers, without concomitant grafting, reduce alveolar ridge resorption after tooth extraction (Lekovic et al. 1998, Vance GS et al. 2004)
Soft tissue management for immediate implants (Becker W 2008, Nasr H.F 2006)
Before implant placement
It is advisable to avoid flap elevation. Care should be taken to protect the buccal plate.
After implant placement (Penarrocha M, 2004)
Primary flap closure over immediately placed implants was considered important for many years. The discrepancy of size and form between the extraction socket and an immediate implant ensures that a space usually exists around the coronal portion of the implant. Bony defects if present in extraction area may be treated with regenerative techniques. Soft tissue coverage of the implant area was considered necessary to achieve bone fill adjacent to the implant. The presence of interdental bone, soft tissue anatomy, smile line, occlusion, and interdental space are all important factors in the placement of immediate implants in the esthetic zone.
Various surgical techniques have been proposed to achieve primary soft tissue closure with immediate implants.
• Use of a rotated buccal flap from an adjacent tooth can be used to achieve closure over implants placed at the time of extraction. This procedure can be applied for single or multiple implant sites and can be employed in conjunction with membrane barriers or various grafting materials. Adequate width of keratinized mucosa and vestibule depth should should be there in this technique.
• Edel was the first to publish on the use of a connective tissue graft for coverage of immediately placed implants. A potential problem is the limitation of donor tissue size.
• An acellular dermal matrix allograft is sometimes employed as an alternative to autologous connective tissue. Acellular dermal matrix has also been used alone or with various grafting materials to cover immediately placed implant sites.
• The palatal advanced flap or pediculated flap is another useful surgical technique for maxillary immediate implant cases. The technique provides adequate tissue mobility and bulk, facilitating a complete, precise, and highly predictable coverage of the extraction site in large defect areas, and in cases of multiple implants. Disadvantage of this technique will be uncomfortable and prolonged secondary palatal tissue healing.
Hard tissue management of dental implants
After the placement of dental implant, the distance between the implant body and the buccal wall of the socket has to be evaluated if this distance is more than 2mm. This distance is called the “jumping distance”. If this distance is 2 mm or more, then it is necessary to graft this zone with a bone graft material.
Any type of graft material including alloplasts can be used to fill this defect. In case the buccal flap or buccal plate has been violated anytime during the procedure, then it is advisable to graft the jumping distance as well as the labial aspect of the implant site and cover it with a membrane. Studies by Chen et al. have shown that when the extraction sockets are not grafted after placement of an implant over a five year period, there has been a progressive loss of buccal bone as well as soft tissue recession.
Because the periodontal ligament provides an adequate blood supply, the labial alveolar bone of natural teeth remains stable for a number of years, even when it is less than 1 mm wide. Even in implants that lack periodontal ligament tissue, alveolar bone that has developed around the implant will supply enough blood as long as it is composed of cancellous bone containing a relatively large number of blood vessels. It is estimated that a labial alveolar bone width of more than 1.2 mm is required to induce cancellous bone beneath cortical bone, which, in turn, maintains long-term tissue stability.
Primary stability
For the implant to integrate there should be no excess movement between the implant and bone during the healing phase. The stability of the implant can be verified using resonance frequency analysis.20, 22 The torque registered on the drilling consul can also be a good indicator of initial implant stability. Torque resistance of 40 Newton centimetres is indicative of initial implant stability. Bone necrosis and implant loss may be possible if excessive torque is applied to the implant because this may strip the implant threads or exert excessive compression on the adjacent bone.
Bone quality (Penarrocha M, 2004)
Bone quality may be manipulated by altering the method of osteotomy preparation and the judicious selection of instruments for this purpose.
The use of bone condensers- trabeculae within cancellous bone may be condensed using a series of osteotomes of increasing diameter to increase the density of bone surrounding the osteotomy.
The use of bone taps- allowing the implant to tap its own thread, resulting in a better fitting implant with increased primary stability.
Cortical engagement- increasing the diameter or length of an implant to engage cortical bone will result in a more stable implant.
Implant design
The shape of the implant and its surface greatly influence primary stability and thus the precondition for osseointegration.
Macro-design- a screw shaped implant with large, deeply cut threads will provide better stability than a tapered push fit implant because of the greater surface area and the configuration of the threads, which will provide anchorage to resist movement that may be caused by multidirectional forces.
Precision of osteotomy- the screw form enables vital bone to come into immediate contact with the entire surface of the implant, including the apex and base of each thread.
Surface- a rough surface provides higher frictional resistance to movement than a smooth surface.
Restorative phase
The restorative phase is similar to that of a conventional implant placement protocol, with the selection of an appropriate abutment and adequate restoration.
Fixture level impressions are frequently made immediately after implant placement. This facilitates the fabrication of prosthetic abutments and provisional restorations. After proper healing interval abutments and provisional restorations can be inserted onto implants . A healing abutment can be inserted on the top of the implant. The healing abutment should be even with, or slightly apical to, the adjacent marginal tissues.
Under minimal tension interproximal papillae adjacent to the implant can be adapted with interrupted sutures. The provisional restoration is then inserted, making certain the pontic is clear of the healing abutment. To support the adjacent tissues and help preserve the soft tissue anatomy adjacent to the implant it should have ovate pontic. The patient is instructed in proper postsurgical care and sutures are removed in 7–10 days.
After osseointegration has been confirmed (maxillary anterior region 4–6 months) restoration of the implants can take place. An immediately placed implant encroaches upon the maxillary sinus, it might be prudent to postpone implant placement, augment the sinus, allow for bone healing, and then place the implant for better results.
Prosthetic considerations for patients requiring implant placement should include evaluation of :
1. Number and location of missing teeth
2. Interarch distance
3. Number, type, and location of implants to be placed
4. Existing and proposed occlusal scheme
5. Design of planned restoration. (Adams D.A 2000)
Abutment connection
A Morse taper connection that is sufficiently tight to prevent bacterial leakage is ideal.
For immediate loading an abutment needs to be connected at the time of implant insertion therefore a broad range and stock of angled abutments that can be connected is needed. The forces necessary to secure the abutment should be such that the implant position is not altered. (Penarrocha M, 2004)
Post-placement procedures: The following considerations should be reviewed prior to the restorative phase:
1. Quantity, quality, and health of soft and hard tissues
2. Implant stability
3. Implant position and abutment selection
4. Oral hygiene assessment. (Adams D.A 2000)
Requirements for long-term success with immediate-loaded implants include:
Temporisation of immediate post extraction implant placement
Can be achieved in two levels:
1. Temporary replacement of the edentulous tooth, thus acting in a non functional loading scenario
2. Single stage protocol where the mouth of the implant is exposed to the oral environment through a gingival former.
Implant management
Periodic evaluation of implants, surrounding tissues and oral hygiene are vital to the long-term success of the dental implant. Considerations in the evaluation of the implant are:
1. Presence of plaque/calculus
2. Clinical appearance of peri-implant tissues
3. Radiographic appearances of implant and periimplant structures
4. Occlusal status, stability of prostheses and implants
5. Probing depths
6. Presence of exudate or bleeding on probing
7. Modification of maintenance interval
8. Patient comfort and function (Adams D.A 2000)
Outcomes assessment
The desired outcome of successful implant therapy is maintenance of a stable, functional, aesthetically acceptable tooth replacement for the patient.
Criteria for success include:
a) Absence of persistent signs/symptoms such as pain, infection, neuropathies, parathesias, and violation of vital structures
b) Implant immobility
c) No continuous peri-implant radiolucency
d) Negligible progressive bone loss (less than 0.2 mm annually) after physiologic remodelling during the first year of function
e) Patient/dentist satisfaction with the implant supported restoration
