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J Oral Maxillofac Surg69:1919-1922, 2011

Buccal to Lingual Transalveolar ImplantPlacement for All On Four Immediate

Function in Posterior Mandible:Report of 10 Cases

Ole Jensen, DDS, MSc,* Jared Cottam, DDS, MD,†

Mark Adams, DDS, MSc,‡ and Scott Adams, CDA§

Purpose: A retrospective study was done to evaluate the use of transalveolar implant placement in themandible posterior to the mental nerve.

Materials and Methods: Ten patient charts were reviewed of twenty implants placed transalveo-larly with evaluation of function, osseointegration, and bone level for 1 year by unregisteredperiapical x-rays.

Results: Ten patients which received twenty transalveolar implants were followed for 1 year. Oneimplant failed. There were no significant complications encountered from the procedure.

Conclusion: All On Four treatment of mandibles with relatively anterior mental nerve locations may besuccessfully treated with transalveolar implant placement posterior to the foramen.© 2011 American Association of Oral and Maxillofacial Surgeons

J Oral Maxillofac Surg 69:1919-1922, 2011

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fter the creation of the mandibular All On Fourhelf1,2 to gain adequate anterior-posterior implantpread in the presence of a relatively anterior men-al foramen location,3-7 buccal bone dehiscence, or

poorly mineralized marrow space,8 transalveolar im-plants can be placed posterior to the foramen. Theseimplants pass buccal to lingual above the nerve togain fixation for immediate function and therefore donot require substantial available bone above the nerve(Fig 1A-C).

Because lingual concavities may be present, theseimplants are not placed directly into the lingual plate,but flare out at a more acute angle, sometimes perfo-rating through the lingual plate (Fig 1D,E).9,10 The

*Private Practice, ClearChoice Dental Implant Center, Green-

wood Village, CO.

†Fellow, Tissue Engineering Institute of Colorado, Greenwood

Village, CO.

‡Private Practice, ClearChoice Dental Implant Center, Green-

wood Village, CO.

§Greenwood Village, CO.

Address correspondence and reprint requests to Dr Jensen: Oral

and Maxillofacial Surgery, 8200 E. Belleview Ave, Suite 520/East,

Greenwood Village, CO 80111; e-mail: ole.jensen@clearchoice.com

© 2011 American Association of Oral and Maxillofacial Surgeons

278-2391/11/6907-0020$36.00/0

roi:10.1016/j.joms.2011.02.042

1919

approach is a fall-back technique where implants can-not be placed just in front of the foramen.

Reported here are findings of 10 consecutive im-mediately loaded buccal to lingual transalveolar posi-tioned mandibular implants for All On Four treatmentwith findings and recommendations for using thetechnique.

Materials and Methods

A retrospective study was performed of cases inwhich mandibular transalveolar implants (angulatedinto the lingual plate) were placed posterior to themental foramen and superior to the inferior alveolarnerve.

Case selection criteria included a minimum of 5mm of vertical bone above the neurovascular canalposterior to the foramen with the nerve in a relativelycentral or lateral intraosseous location. Poor boneanterior to the foramen, including failed attempts atplacing implants into reticular marrow space, absenceof buccal cortical plate,7 thin hour glass anterior alve-

lus,11 or prominent lingual concavities were prereq-isites for using the technique.9,10 Transalveolar im-lants were placed at a lingual directed angle, distal tohe mental foramen, to gain adequate anterior-poste-ior spread and immediate function for a screw-re-ained provisional prosthesis. Ten cases were selected

etrospectively, which were followed radiographi-

t

1920 BUCCAL TO LINGUAL TRANSALVEOLAR IMPLANT PLACEMENT FOR ALL ON FOUR

FIGURE 1. A, The All On Four shelf provides a technique for determining optimal implant sites and implant angulation, but when the mentalforamen is anterior or anterior sites are ablated, implants can be placed posteriorly going transalveolarly, buccal to lingual, missing theneurovascular bundle. B, A posterior transalveolar implant is angled 30° to the lingual plate from access at the All On Four shelf posterioro the mental foramen. C, Transalveolar implant placement must have some available bone above the nerve and at the lingual plate, whichcan sometimes be compromised by a lingual concavity. D, E, Posterior implants for the All On Four are placed well behind the mental foramenbut angled lingually to avoid the nerve. F, A posthealing CAT scan shows the lingual placement of an osseointegrated transalveolar implantgaining fixation (*) at the lingual plate. Note the mental foramen (arrow) just in front of the implant body. No paresthesia resulted from implantplacement.

Jensen et al. Buccal to Lingual Transalveolar Implant Placement for All On Four. J Oral Maxillofac Surg 2011.

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JENSEN ET AL 1921

cally with periapical x-rays for up to 1 year. Grossbone loss was measured using unregistered periapicalx-rays. Findings related to the titanium bar prosthesiswere analyzed using standard laboratory protocols todetermine a passive fit.

This case report met the conditions for exemptionfrom the Institutional Review Board. The data existingat this time and the information were recorded insuch a way that the subjects could not be identified.This study will not be submitted to the US Food andDrug Administration for marketing approval.

This case report features human subjects and wehave read and followed the guidelines of the HelsinkiDeclaration.

Results

Ten of 10 patients proceeded to immediate provi-sionalization using transalveolar implants posteriorly.A total of 20 transalveolar implants were inserted.Insertion torque was 50 N-cm or greater for all im-plants placed. Nineteen of 20 implants remained fullyosseointegrated after 1 year. There was no instance ofparesthesia. Bone loss patterns were similar to adja-cent implants with bone loss less than 1 mm for allimplants except for 1 that had lost 2 mm of bone. Allprostheses remained in function during the study pe-riod. Final bar fabrication was facilitated with passivefit in all cases.

Discussion

Surgical strategies to gain osseointegration may notalways be favorable for prosthetic design and long-term function.12,13 Sites that are relatively unusual for

xation include the pterygoid plate, the zygoma, andhe vomer in the maxillary region,14-17 but in theandible, the use of the lingual plate is not consid-

red unusual, although the purposeful placement ofmplants transalveolarly to engage lingual plate tomerge buccally must be considered outside theainstream of surgical prosthodontic protocol.10,18

However, for the surgeon who must find availablebone stock to exploit, in this case a secondary fall-back site for immediate function for the All OnFour,19 the use of this unusual approach to gain im-

lant fixation remains credible.With transalveolar placement, the more the implant

arallels the lingual cortex, the greater the implantength can be. By contrast, implants placed angledway from the lingual plate will be shorter in lengtho avoid coming out into the vestibule. Therefore, these of a transalveolar approach requires modificationf implant placement thinking and a prosthodontic

indset.20,21 b

Using the above placement criteria, the followingformulation may help both prosthodontist and sur-geon establish optimal implant positioning in thisproblem-solving setting where all other implant inser-tion options failed to provide fixation.22

The net effect of this treatment formula is to estab-lish sufficient length of implant for immediate load,which by inference is 10 mm or greater in length.23

Using a transalveolar technique often provides im-plant lengths of 10 to 13 mm within a flare angle of upto 30°. When the implant flare angle is considerablyless than 30°, such as 10°, the implant may slip freefrom lingual plate fixation, whereas greater than 30°leads to buccal emergence.24

The axial plane for angled implant placement iscompensated for by a 30° angled abutment. This sameangled abutment, by rotation at the internal hex, com-pensates for the flare angle in the coronal plane. Thissuggested maximum limit for angulation permits a 2plane geometric approach to surgical placement.

The question arises: why not use a guided surgeryapproach for All On Four treatment to help solve theproblem? This can sometimes be performed in anedentulous setting. However, when there is signifi-cant bone reduction required to create the All OnFour shelf and provide interrestorative space, the useof computer guidance systems becomes nearly impos-sible.25,26 Many All On Four patients are dentate,

aking guided surgery difficult. Also, computers doot sense insertion torque or the primary fixationequirement for immediate function, which relies onhe tactile sense of the surgeon.

Figure 1A-E shows a transalveolar implant in whichhe distal angulation of 30° is maintained, but themplant is allowed to flare out buccally at about 30° tongage the lingual plate. As long as the crestal posi-ion of the implant does not end up too far lateralo the midaxial line, a 30° abutment will correctoth the distal and the flare angles of 30°, ofteneeping the abutment screw access within restorativeooth structure. When the flare angle exceeds 30° orhe implant is left to emerge buccal to the midaxialine, then screw access will be lateral to the buccalusp. Large angles such as 45° will lead to a vestibularcrew access hole, which can be unsatisfactory pros-hetically, and implants will be shorter in length. Ineneral, the more the flare angle, the shorter themplant length. Conversely, the less the flare angle,he less fixation potential within the lingual plate.

One final consideration that advocates for thisew approach is avoidance of nerve injury. Some-imes surgeons, in an effort to gain anterior-posteriorpread, become too close to the mental nerve leadingo nerve impingement. This can occur when the men-al foramen is relatively anterior. By placing implants

ehind the foramen, although there may not be room

1922 BUCCAL TO LINGUAL TRANSALVEOLAR IMPLANT PLACEMENT FOR ALL ON FOUR

for vertical implant placement, there is often enoughbone available vertically and lingual to gain sufficientosseointegration for immediate load. This leads to amuch improved anterior-posterior spread for long-term function. Also, almost all transalveolar implantsemerge within the occlusal of the molar teeth so thatno cantilever is required.

In summary, the use of a buccal to lingual transal-veolar implant placement strategy posterior to themental foramen enables implants to both avoid thenerve and gain anterior-posterior spread using a distalangulation of 30° as well as a flare angulation of 30°.These angles may still keep the abutment near themidaxial line as well as allow sufficient purchase intolingual bone for fixation for immediate function. Thistechnique can salvage immediate function when pri-mary implant sites fail to gain adequate insertiontorque.

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dibular foramen: Preliminary radiological study. Surg RadiolAnat 32:927, 2010

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