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All-on-4® Implant Treatment: Common Pitfalls and Methods to Overcome Them

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Abstract and Figures

Although highly successful in terms of both short- and long-term survival rates, All-on-4®–style dental implant treatment is a multistep process with many potential complications. Beyond reports of survival rates for dental implants and the final prostheses, the dental literature is relatively devoid of information regarding obstacles and pitfalls associated with All-on-4–style dental implant treatment. In the current article, the author describes common issues that he has encountered before, during, and after All-on-4–style dental implant treatment of more than 500 arches and discusses methods for overcoming these obstacles.
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458 Volume 37, Number 7COMPENDIUM July/August 2016
Since its introduction to dental literature in 2003,1 the
All-on-4® (Nobel Biocare, www.nobelbiocare.com)
treatment concept has proven to be a predictable
2,3
and cost-eective4 method used for full-arch dental im-
plant rehabilitation. True adherence to this manner of
treatment involves restoring an arch with at least 4 dental implants,
the distal of which are tilted up to 45 degrees, and immediately
loading a screw-retained provisional prosthesis.5 Various articles
have documented both short- and long-term success rates for All-
on-4–style treatment, with dental implant and prosthetic survival
rates consistently exceeding 98%.
1-12
While these studies document
the success rates for this treatment concept and others discuss
variations on surgical design to accommodate specific anatomic
situations,13-16 few studies examine complications associated with
the procedure beyond standard infections or mechanical fracture
of the prosthesis.1-20
Accordingly, the purpose of this article is to present obstacles and
complications that may be encountered before, during, and after
All-on-4–style treatment and how to manage them. The author
draws on his experiences with treating more than 500 arches and
more than 2000 dental implants using All-on-4–style treatment.
Presurgical Complications
Teeth Exfoliating With Initial Impressions
Many patients requiring All-on-4–style treatment have extremely
compromised teeth that may be unintentionally removed during
the initial impression process. This is typically due to severely
decayed teeth or extremely mobile teeth secondary to advanced
periodontal disease (Figure 1). Such situations must be recognized
and these patients advised of the potential for tooth loss during
the impression process.
When encountering teeth that have been exfoliated with impres-
sions, the author typically cleans the exfoliated tooth and adjusts
the length of the root so that the tooth may be temporarily bonded
back into place using composite resin in a Maryland-bridge fash-
ion. Occlusion is adjusted on the bonded tooth so that it makes no
contact with opposing teeth.
On some occasions, the author has bonded patients’ natural
exfoliated teeth to their existing removable partial prostheses. In
select cases in which no adjacent teeth or removable prostheses
are available for bonding of an exfoliated tooth, the author has
used a transitional mini dental implant with a chairside-fabricated
temporary crown as in interim restoration prior to the patient’s
surgical procedure.
Intrasurgical Complications
Arterial Disruptions During Mucogingival Flap Reflection
Following the administration of local anesthesia, the first step in
All-on-4–style treatment is full-thickness mucogingival flap reflec-
tion. Depending on anatomic variability, vasculature such as the
All-on-4® Implant Treatment: Common Pitfalls
and Methods to Overcome Them
Dan Holtzclaw, DDS, MS
CONTINUING EDUCATION 4
COMMON IMPLANT OBSTACLES
Abstract: Although highly successful in terms of both short- and long-term
survival rates, All-on-4®–style dental implant treatment is a multistep process
with many potential complications. Beyond reports of survival rates for dental
implants and the final prostheses, the dental literature is relatively devoid of
information regarding obstacles and pitfalls associated with All-on-4–style
dental implant treatment. In the current article, the author describes common
issues that he has encountered before, during, and after All-on-4–style dental
implant treatment of more than 500 arches and discusses methods for over-
coming these obstacles.
• discuss complications that
may be encountered with
the All-on-4 implant
concept before, during,
and after treatment
• describe intrasurgical
obstacles associated with
the All-on-4–style approach
and how to alleviate them
• explain why fracturing of
provisional restorations
may occur following All-
on-4–style implant surgery
LEARNING OBJECTIVES
greater palatine artery or sublingual artery, or various branches
thereof, may be disrupted. Should this occur, excessive hemor-
rhaging may obscure visibility of the surgical field in addition to
becoming a hazard for the patient.
Initial treatment in these situations involves administration
of local anesthetic with at least 1:100,000 epinephrine.21 In most
cases, the vasoconstrictor eect of epinephrine is enough to stop
the hemorrhaging. Should the vasoconstrictor fail to alleviate the
problem, an electrosurgical generator or laser with a coagulation
setting may be applied to the source of hemorrhage. A third option
Fig 1.
Fig 4.
Fig 2.
Fig 1. Presurgical panoramic radiograph of a patient with severe peri-
odontal disease and who is an All-on-4–style treatment candidate.
Fig 2. Sublingual arterial branch tied o with 4-0 chromic gut suture.
Fig 3. Presurgical cross-sectional CBCT scan slice of an All-on-4–style
dental implant patient with crestal location of the inferior alveolar
nerve (yellow crosshairs on nerve) secondary to bone resorption.
Bone reduction in this location risks exposure and damage to the
nerve. Fig 4. Presurgical panoramic radiograph of an All-on-4–style
patient with pneumatized maxillary sinuses that extend beyond the
planned horizontal plane of bone reduction (yellow line).
for containing the bleed is to use a resorbable suture to tie o the
vessel posterior to the site of hemorrhage (Figure 2).
Exposed Nerves
In cases of severe mandibular atrophy, supracrestal exposure of
the mental foramen or inferior alveolar nerve (Figure 3) may be
possible.
8,22
When encountered, these situations require special
consideration for incision design, mucogingival flap reflection,
bone reduction, dental implant placement, soft-tissue reduction,
and suturing. With exposed nerve tissue, each of these steps has
the potential for causing damage.
When faced with an exposed inferior alveolar nerve, the au-
thor has placed dehydrated human amnion-chorion membrane
(DHACM) directly onto the nerve fibers based on the positive
outcomes that have been reported with DHACM nerve wraps
around the prostatic neurovascular bundle in prostatectomy
surgeries.23 In 4 cases of DHACM that the author used inferior
alveolar nerve wraps, patients reported no adverse outcomes,
such as permanent or transient anesthesia, paresthesia, hypo-
esthesia, or dysesthesia.
Pneumatized Maxillary Sinus Extending Below Bone
Reduction Plane
It is well established that maxillary sinus pneumatization may
occur following posterior maxillary tooth loss.24 In select cases,
pneumatization of the maxillary sinus may extend beyond the
anticipated horizontal plane of bone reduction required for All-
on-4–style treatment (Figure 4). Failure to adequately reduce
bone in these areas may lead to restorations of inadequate thick-
ness that are at increased risk for fracture.25 Conversely, standard
bone reduction in these areas may lead to significant damage to
the Schneiderian membrane.
To overcome this complication, the author carefully reduces
the residual maxillary crestal bone until crestal exposure of the
Schneiderian membrane is achieved (Figure 5). On crestal visu-
alization of the Schneiderian membrane, the author uses curettes
to lift the membrane apically from the anticipated plane of bone
reduction (Figure 6). The maxillary bone is then reduced apically,
and the process is repeated until the desired amount of bone reduc-
tion is achieved. When performed in this manner, the Schneiderian
membrane remains intact while crestal areas of reduced maxil-
lary bone will have openings of varying degrees depending on the
amount of bone reduction (Figure 7). The author does not augment
these openings with bone graft and simply closes the surgical site
with primary closures of thick mucogingival flaps. To date, patients
receiving treatment from the author in this fashion have had no
adverse outcomes (Figure 8).
Hemorrhage From Osseous Nutrient Canals
All-on-4–style treatment typically involves reduction of alveolar
and/or basal bone (Figure 9) to achieve adequate restorative space
for both the interim and final prostheses.25-27 During reduction of
this bone, exposure of intraosseous nutrient canals
28,29
may lead to
hemorrhaging that may obscure visualization of the surgical field. If
left uncontrolled, hemorrhaging from nutrient canals can become
460 Volume 37, Number 7COMPENDIUM July/August 2016
CONTINUING EDUCATION 4 | COMMON IMPLANT OBSTACLES
Fig 3.
ing the anterior-posterior spread of the All-on-4–style prosthesis.
Furthermore, in cases in which accessory mental foramina are
located superior to the main mental foramen,
30
the amount of bone
reduction may be compromised, increasing the risk for prosthetic
fracture.
25
Presurgical cone-beam computed tomography (CBCT)
scans and radiographs for proposed All-on-4–style surgeries should
be scrutinized for accessory mental foramina (Figure 13). Notably,
dental literature has shown that even with careful evaluation of
CBCT scans, it is not possible to identify 100% of accessory mental
foramina cases.
31
As such, care should be taken during mucogingival
flap reflection to search for this anatomic anomaly.
When encountering accessory mental foramina, the author has
performed modifications to bone reduction and/or more mesial
placement of posterior dental implants; on a few occasions, he
has carefully dissected the nerve from the accessory mental fora-
men and relocated it to a more distal position. To date, the author
has had no adverse outcomes in patients, such as permanent or
transient anesthesia, paresthesia, hypoesthesia, or dysesthesia,
resulting from this technique.
Fig 5. Fig 7.
Fig 8.
Fig 6.
Fig 5. Crestal exposure of the Schneiderian membrane at the initiation of horizontal plane bone reduction. Fig 6. Curette used to elevate
Schneiderian membrane from residual crest to allow for additional horizontal plane bone reduction. Fig 7. Maxillary arch from Figure 5 and Figure 6
following crestal Schneiderian membrane elevation, horizontal plane bone reduction, and dental implant placement. Fig 8. Postsurgical panoramic
radiograph of patient shown in Figure 5 through Figure 7. Fig 9. Alveolar bone reduction prior to dental implant placement in a mandibular All-on-4–
style dental implant surgery. Fig 10. Woodson hand instrument used to condense bone at the site of an intraosseous nutrient canal hemorrhage.
significant, resulting in excessive blood loss. It is not uncommon
to encounter multiple concurrently hemorrhaging intraosseous
nutrient canals, especially during mandibular bone reduction.
When faced with this situation, the author uses the blunt end
of a handheld instrument, such as a Woodson instrument (Figure
10), to put heavy pressure on bone directly adjacent to the bleeding
nutrient canal. This pressure typically deforms the adjacent bone to
a point at which it occludes the hemorrhaging. The author has en-
countered hundreds of hemorrhaging intraosseous nutrient canals
and has never had this technique fail to achieve the desired results.
Accessory Mental Foramina
The prevalence of accessory mental foramina is well documented
in dental literature with findings from 2.7% to 13% (Figure 11).30-
32
Accessory mental foramina pose a particular obstacle for All-
on-4–style treatment because the mental foramen is the landmark
used to determine the posterior limits of tilted implant placement
(Figure 12).
9
The presence of accessory mental foramina often
requires more mesial placement of dental implants, thus limit-
Fig 9. Fig 10.
461
www.compendiumlive.com July/August 2016 COMPENDIUM
Sublingual Artery Insertion in the Anterior Mandible
Because All-on-4–style treatment in the mandible requires dental
implant placement anterior to the mental foramina, special consid-
eration should be given to the vasculature in this region. A number
of articles have reported potentially life-threatening complications
when dental implant placement has damaged vasculature in the ante-
rior mandible. A 2015 literature review
33
on immediate or immediate
postoperative bleeding complications in implant dentistry noted that
the most common cause of bleeding complications was damage to
the sublingual artery. Although this literature review noted an ab-
sence of fatalities, advanced airway management by intubation was
needed in 41% of patients and tracheostomy was required in 47% of
patients. Certainly, avoidance of the sublingual artery during implant
placement in the anterior mandible is paramount.
Cadaveric34,35 and CBCT36 assessments of vascular supply to the
anterior mandible have found that lingual foramina for insertion of
the sublingual artery most commonly occurs in the midline of the
mandible. While the location of sublingual artery insertion in the
anterior mandible is typically beyond the depth of bone reduction
required for most All-on-4–style surgeries, it may be encountered
in cases of severely resorbed mandibles. Furthermore, while den-
tal implant placement is typically not required in the mandibular
midline for All-on-4–style treatment, it is occasionally necessary to
place a dental implant in this location. When faced with this situation,
the author has modified the total amount of bone reduction in the
anterior mandible to allow for safe placement of a dental implant
that avoids vascular impingement while still enabling adequate
prosthesis thickness.
Inadequate Bone Density
Multiple studies indicate that a high degree of primary implant
stability is a prerequisite for the successful immediate loading
of dental implants37,38 and that high insertion torque values are
correlated to high primary implant stability.39-42 Insertion torque
and primary implant stability have proven to be substantially
dependent on bone density with denser bone producing a more
favorable situation.
42
In cases of inadequate bone density, or
“soft bone,” some authors have recommended underpreparing
dental implant osteotomies to achieve improved implant stabil-
ity.7,9 Although this technique is effective in many cases, select
instances arise in which underpreparing the bone still results in
low initial torque values.
When such instances occur, whether in the mandible or maxilla,
the author first attempts to place a larger-diameter implant of
the same length as the implant that failed to achieve high initial
torque value. Should this adjustment prove ineective, a longer
implant of a larger diameter is then used. In the maxilla, the lon-
ger implant may engage the vomer or lateral piriform rims to
achieve apical stability.
13
In the mandible, the author achieves
primary implant stability by engaging the cortical bone at the
inferior border of the mandible with the apical portion of the
dental implant (Figure 14 and Figure 15).
Removal of Dental Implants
All-on-4–style treatment sometimes requires the removal of previ-
ously placed dental implants (Figure 16 and Figure 17). Although
some of these implants may have biologic complications such as
peri-implantitis that may ease the removal process, most previ-
ously placed implants requiring explantation by the author have
been firmly osseointegrated. Previously placed dental implants are
not typically suitable for All-on-4–style surgeries because the plat-
forms were placed to a level in accordance with the natural teeth.
462 Volume 37, Number 7COMPENDIUM July/August 2016
CONTINUING EDUCATION 4 | COMMON IMPLANT OBSTACLES
Fig 11. Accessory mental foramina (arrows)
encountered during mandibular All-on-4–
style dental implant surgery. Fig 12. CBCT
imaging of accessory mental foramina from
Figure 11. Fig 13. Mental foramen used to
determine the posterior extent of tilted
dental implant placement in a mandibular
All-on-4–style dental implant surgery. Fig
14. Postsurgical panoramic radiograph of
All-on-4–style dental implant surgery with
dental implants engaging cortical bone at
the inferior border of the mandible. Fig 15.
Cross-sectional CBCT scan slice from Figure
14 showing apical engagement of the dental
implant with the dense cortical bone at the
inferior border of the mandible.
Fig 11.
Fig 14.
Fig 12.
Fig 15.
Fig 13.
Although this is perfectly suitable when natural teeth are present,
these platform positions are too coronal for All-on-4–style treat-
ment. Furthermore, previously placed dental implants preclude
the ability for adequate bone reduction. In the author’s experi-
ence, using previously placed dental implants for All-on-4–style
treatment often results in restorations of inadequate thickness
that have a propensity for fracture due to the coronal position of
the platforms and the lack of bone reduction. As such, the author
routinely removes previously placed dental implants when per-
forming All-on-4–style treatment.
Dental implant removal for All-on-4–style surgery is particu-
larly concerning because of the need for immediately loading a
prosthesis. Dental implants requiring removal are typically the
same diameter as the implants intended for use in the All-on-4–
style surgery. If the implants can be removed with a high-torque
dental implant retrieval tool (Figure 18), bone is preserved and a
dental implant of at least the same diameter and length can be used
for the All-on-4–style treatment. Should the implant retrieval tool
fail to explant the previously placed dental implant, trephination
is required. The bone loss subsequent to trephination of a dental
implant may eliminate the possibility of placing a new implant and
thus compromise immediate loading of a transitional prosthesis.
As has been reported by others,
43-45
the author has had a high degree
of success in removing previously placed dental implants with
high-torque retrieval tools. In cases in which trephination was
required, the author has replaced the previously existing implants
with new implants of both wider and longer dimensions.
Postsurgical Complications
Fracture of Provisional Restorations
Postsurgical biologic complications following All-on-4–style den-
tal implant surgery are rare.
1-12
The most common postsurgical
complication following this surgery noted in the dental literature
is fracture of the provisional restoration, with rates from 4.17%
to 41%.
46-48
Fractures of provisional All-on-4–style restorations
during healing are concerning, because they eliminate cross-arch
stabilization and disrupt stress distribution patterns. Furthermore,
fractures of these prostheses are unsettling to patients because
they impair masticatory function and marginalize esthetics. The
most common causes of fractured All-on-4–style provisional res-
torations are prostheses of inadequate thickness due to under-re-
duced bone, processing errors, or improper occlusal adjustment.
46
In some cases, however, fractures may occur because acrylic and
polymethyl methacrylate materials are inadequate for extended
periods of heavy occlusal use.
To reduce the incidence of postsurgical fracture of All-on-4–
style provisional restorations, the author reinforces transitional
prostheses with 1-mm-diameter interplaited steel wire (Figure 19
and Figure 20) based on the findings of research by Yamaguchi et
al,49 Li et al,50 and others.51-53 Upon incorporating this reinforce-
ment technique for All-on-4–style provisional restorations, the
rates of fracture for the author’s provisional restorations decreased
from 16.14% to 4.17%.46
Conclusion
Although All-on-4–style full-arch dental implant procedures
have one of the highest success rates of any treatment in dental
literature, the technique is also among the most dicult and can
be fraught with obstacles. With careful planning and knowledge
of potential pitfalls associated with performing the procedure, cli-
nicians can incorporate All-on-4–style dental implant treatment
into their practices with a high degree of confidence and less stress.
463
www.compendiumlive.com July/August 2016 COMPENDIUM
Fig 16. Presurgical panoramic radiograph
of a patient receiving All-on-4–style treat-
ment with multiple dental implants requir-
ing explantation. Note the dental implants
in the mandibular right quadrant that are
compromising the inferior alveolar nerve.
Fig 17. Postsurgical panoramic radiograph
of the patient from Figure 16 following All-
on-4–style dental implant treatment. Fig
18. High-torque retrieval tool being used
to remove dental implant during All-on-4–
style treatment. Fig 19. All-on-4–style tran-
sitional restoration being fabricated with
interplaited steel wire for reinforcement.
Fig 20. Finished All-on-4–style transitional
restoration from Figure 19.
Fig 16. Fig 17. Fig 18.
Fig 19. Fig 20.
DISCLOSURE
The author had no disclosures to report.
ABOUT THE AUTHOR
Dan Holtzclaw, DDS, MS
Consultant Faculty, US Navy Postgraduate Dental School, Department of
Periodontics, Bethesda, Maryland; Private Practice, Austin, Texas
Queries to the author regarding this course may be submitted to
authorqueries@aegiscomm.com.
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465
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... Studi ini mendokumentasikan tingkat keberhasilan untuk konsep perawatan ini dan yang lainnya membahas variasi desain bedah untuk mengakomodasi situasi anatomi tertentu, beberapa penelitian juga membahas komplikasi yang terkait dengan prosedur di luar infeksi yang biasa terjadi atau fraktur mekanis dari prostesis. 5 Artikel ini menyajikan kendala dan komplikasi yang mungkin ditemui sebelum, selama, dan setelah perawatan konsep All-on-4 dan cara mengelolanya. ...
... Ketika terjadi kasus tersebut, maka dibutuhkan pertimbangan khusus untuk desain insisi, refleksi flap mukogingiva, reduksi tulang, penempatan implan gigi, reduksi jaringan lunak, dan tindakan penjahitan, karena setiap langkah berpotensi menyebabkan kerusakan. 5 Ketika menemukan saraf alveolar inferior yang terbuka, sebaiknya menempatkan membran amnionkorion manusia yang didehidrasi (DHACM) langsung ke serabut saraf. Pembungkus saraf dengan DHACM di sekitar bundel neurovaskular prostat pada operasi prostatektomi. ...
... Sebaliknya, pengurangan tulang minimal di area ini dapat menyebabkan kerusakan yang signifikan pada membran Schneiderian. 5 Untuk mengatasi komplikasi ini, sebaiknya mengurangi sisa tulang crestal RA secara seksama sampai crestal terpapar dari membran Schneiderian. Visualisasi puncak membran Schneiderian digunakan kuret untuk mengangkat membran tersebut. ...
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The All-on-4® concept is one of the treatment procedures used in total edentulous patients and as an alternative to the routine care of conventional dentures with successful results in short term, long term and retrospective studies. What needs to be con-sidered in alternative treatments lies in the success of the prosthesis and its prosthodontic perspective which involves the princi-ples of occlusion. This article reviews the All-on-4® concept and its prosthodontic aspects. All-on-4® style dental implant treat-ment is a multi-step process with many potential complications. Reports of success rates for dental implants and final prosthe-ses have been widely published while the dental literature on the barriers and difficulties associated with the treatment of dental implants with the All-on-4 concept has not been widely reported. In the current article, the author describes common problems before, during, and after All-on-4 style dental implant treatment of more than 500 arches and discusses methods for overcoming those barriers.
... Also, the implant cumulative survival and success rates were 93.0% and 91.7%, respectively, from a total of 1,884 implants. [2][3][4][5][6] While most of the related research, documents the success rate for this treatment concept, fewer studies discuss variations in surgical protocol for specific anatomic situations and complications associated with the procedure other than infections or mechanical fracture of the prosthesis. [7][8][9][10] So the aim of this article is to give a detailed description of the possible complications any clinician/implantologist may encounter during the All-on-4® treatment procedure and propose a classification system for ease of application and reproducibility. ...
... The exfoliated teeth can be temporarily bonded back to neighboring teeth using composite resins with no opposing tooth contact or can be incorporated to their existing removable partial dentures until surgery. [5] Intraoperative Complications heavy pressure on bone directly adjacent to the bleeding nutrient canal. [5] In cases of severe mandibular atrophy, supracrestal exposure of the mental foramen or inferior alveolar nerve may be possible. ...
... [5] Intraoperative Complications heavy pressure on bone directly adjacent to the bleeding nutrient canal. [5] In cases of severe mandibular atrophy, supracrestal exposure of the mental foramen or inferior alveolar nerve may be possible. When encountered, these situations require special consideration for incision design, mucogingival flap reflection, bone reduction, dental implant placement, soft-tissue reduction, and suturing. ...
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To overcome the anatomical limitations of conventional dental implant surgeries in the severely atrophied posterior maxilla or mandible, All-on-4® procedure with posterior tilted implants was introduced. Even though this procedure has a proven success rate, it is a very technique sensitive procedure with chances of complication at each stage. So the purpose of this review is to give a detailed description of all the possible complications encountered by any clinician during the treatment procedure and propose a precise and wholesome classification system for the same.
... 11 On occasion, the lower bone density of the maxilla coupled with limited bone availability may result in composite insertion torques that fail to meet the requirement for immediate loading. 12 On other occasions, composite insertion torque may be adequate, but extensive pneumatization of the maxillary sinus migrates the anterior sinus wall so far mesially that inadequate anterior-posterior implant spread (AP-spread) results in distal extension cantilevers of excessive length. 12 Encountering such scenarios during maxillary All-On-4™ surgery is distressing and often cannot be predicted even with the most careful pre-operative planning. ...
... 12 On other occasions, composite insertion torque may be adequate, but extensive pneumatization of the maxillary sinus migrates the anterior sinus wall so far mesially that inadequate anterior-posterior implant spread (AP-spread) results in distal extension cantilevers of excessive length. 12 Encountering such scenarios during maxillary All-On-4™ surgery is distressing and often cannot be predicted even with the most careful pre-operative planning. 12 For the inexperienced surgeon, options at this point are limited and undesirable with one choice being the delivery of a traditional denture in lieu of a fixed prosthesis and the other being delivery of an extremely short fixed prosthesis that results in a truncated arch. ...
... 12 Encountering such scenarios during maxillary All-On-4™ surgery is distressing and often cannot be predicted even with the most careful pre-operative planning. 12 For the inexperienced surgeon, options at this point are limited and undesirable with one choice being the delivery of a traditional denture in lieu of a fixed prosthesis and the other being delivery of an extremely short fixed prosthesis that results in a truncated arch. For the expe- ...
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Introduction: The pterygomaxillary complex is a known anchorage location for dental implants that is typically reserved for use in compromised situations. The dense bone in this area provides excellent insertion torque for dental implants and has been associated with high survival rates in delayed loading scenarios. To date, no known studies have specifically evaluated pterygoid anchored dental implants for immediately loaded full arch restorations. As such, the goal of this paper is to evaluate the Pterygoid Fixated Arch Stabilization Technique (PFAST) protocol for implant insertion characteristics and success when pterygoid implants are used for immediately loaded full arch scenarios. Methods: A retrospective chart review was performed for all patients that were treated with the Pterygoid Full Arch Stabilization Technique (PFAST) protocol. There were no exclusion criteria. Implant insertion torque, mesiodistal angulation, and survival rates were evaluated. Results: A total of 25 dental implants placed in 16 patients were identified as meeting the criteria set for this study. A total of 13 females and 3 males were treated with an average age of 59.87 ± 6.88 years (range 48-72). Pterygoid dental implants used in the current study had 100% survival rates with follow-up times ranging from 6-40 months. Average insertion torque value for the pterygoid dental implants was 44.52 ± 11.89Ncm. Average mesiodistal insertion angle for the pterygoid dental implants was 70.08 ± 7.41º. Prosthetic survival rates with 6-40 months of follow-up were 100%. Conclusions: The PFAST technique provides a means to attain high insertion torque values for dental implants and serves as an adjunct for All-On-4 dental implant treatment during certain compromised situations. When properly applied, pterygoid implants have demonstrated high survival rates in delayed loading situations and the current study shows that they may be successfully applied with immediately loaded full arch situations as well. Additional studies are warranted to confirm these findings.
... Most of these fractures occur because poly methyl methacrylate material has low rigidity to withstand an extended period of heavy occlusal loads. (15)(16) Immediate loading concept in implant prosthesis, we use either semi-rigid splinting with acrylic resin or rigid splinting by a metal bar.Splinting (rigid or non-rigid) has been indicated to prevent axial rotation and movement of implants submitted to immediate loading (17)(18) In 2006 Degidi introduced a new protocol called "syncrystallization" It is a rigid temporization of immediately loaded multiple implants with metal reinforced acrylic resin restorations. A prefabricated titanium bar is welded to implant abutments directly in the oral cavity. ...
Chapter
In today’s world, restoring function and esthetics in fully edentulous patients has gone beyond the conventional treatment of removable dentures to enter the domain of full-mouth rehabilitation with implants. The All-on-fourTM concept was initially introduced in 2003 as a treatment for edentulous mandibles followed by immediate loading. However, it has now become a common line of treatment for both edentulous, often atrophic, arches, with various restorative options depending on the case’s requirements. This chapter aims at discussing the All-on-four concept, its variants, and workflow, both conventional and digital, along with the biological and technical complications associated with this technique.
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Background: Immediately loaded full arch dental implant restorations rely on immediately delivered acrylic provisional restorations for esthetics, masticatory function, and cross arch stabilization. These provisional restorations may be in function from 4-12 months prior to delivery of a definitive final restoration. Fracture of the acrylic provisional restoration during the healing phase has been reported anywhere from 11-40% of cases in dental literature. Recent studies have suggested that reinforcement of the provisional restoration with a variety of materials may improve rigidity and decrease fracture rates. The purpose of this retrospective review is to evaluate if reinforcement of immediately loaded full arch transitional dental implant restorations has any effect on fracture rates during the healing phase. Case Series: A retrospective chart review was conducted for all patients treated with the All- On-4 treatment concept at the private practice of the author in Austin, Texas between January 2014 and March 2016. A total of 69 men and 112 women with a mean age of 61.6 years were treated with the All-On-4 treatment concept using 1182 dental implants. A total of 243 dentate and 14 edentulous arches were treated. Non-reinforced transitional restorations had a fracture rate of 16.14% while reinforced transitional restorations had a fracture rate of 4.17%. There was no difference in overall dental implant survival between the two groups. Conclusions: Reinforcement of All-On-4 acrylic provisional restorations with interplaited steel wire reduces fracture rates. Further studies are warranted to investigate whether or not these reduced fracture rates have any effect on dental implant survival.
Article
Full-text available
Purpose To determine the prevalence and anatomical features of accessory mental foramina (AMFs) associated with neurovascular bundle using reformatted CBCT images in Korean population. Materials and methods Three-dimensional, cross-sectional, and axial images of CBCT from total 446 patients were evaluated. To include only AMF associated with neurovascular bundle, the course of accessory nerve through AMF was evaluated on three-dimensional images. The prevalence, locations to mental foramen (MF), and distribution to the adjacent tooth of AMF were analyzed. Additionally, the distance from MF and dimension of AMF were measured. Results AMFs were found in 36 (8.1 %) patients in the 446 Koreans. The prevalence rate of AMFs in male was significant higher than that in female (p < 0.05). Most AMFs were located anterior–superior to MF. The shortest distance between the center of AMF and that of MF was 5.80 mm (SD ± 2.90, 1.40–13.0). Variance of location of AMF in relation to MF was greater in the horizontal direction than in the vertical direction. In related to adjacent tooth, AMF was mainly distributed between the first and second premolars. The horizontal dimension and vertical dimension of AMF were 1.54 mm (SD ± 1.41, 0.70–9.80) and 1.44 mm (SD ± 0.41, 0.70–2.30), respectively. Conclusions Knowledge of AMF is important for performing effective nerve block and avoiding injuries to neurovascular bundles passing through AMF. Evaluation of the course of AMF in three-dimensional image of CBCT is effective for confirming AMF associated with inferior alveolar nerve.
Article
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Purpose: To investigate the incidence and anatomical location of mandibular nutrient canals (NCs) originating from the mandibular canal using dental cone beam computed tomography (CBCT). Methods: CBCT images from 105 patients were examined to evaluate the presence, number, diameter, and course of NCs. Results: NCs and their foramina were bilaterally located in 17 (16.2 %) images. The mean diameters of NCs and foramina were 0.9 ± 0.4 (range, 0.2-3.2) mm and 0.9 ± 0.4 (0.2-2.1) mm, respectively. NCs coursed through the mandibular incisor region up to the lingual surface of the alveolar bone crest. Conclusion: The present study revealed the frequency and distribution of NCs using CBCT image analysis. NCs are important because surgical injury to the neurovascular bundle within these canals can lead to excessive bleeding and postoperative paresthesia. The identification of NC on CBCT images may be useful during the harvesting of bone blocks or placement of endosseous implants in the anterior region of the mandible.
Article
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Objectives: Heat-polymerized acrylic resin has been the most commonly used denture base material for over 60 years. However, the mechanical strength of acrylic resin is not adequate for long-term clinical performance of dentures. Consequently, fracture is a common clinical occurrence, which often develops in the midline of the denture base. This study aimed to evaluate the efficacy of cold-cure and heat-cure acrylic resins, reinforced with glass fibers, polyethylene fibers, and metal wire for denture base repair. Materials and methods: Ninety specimens were prepared and allocated to nine groups. Ten specimens were considered as controls, and 80 were divided into 8 experimental groups. In the experimental groups, the specimens were sectioned into two halves from the middle, and were then divided into two main groups: one group was repaired with heat cure acrylic resin, and the other with cold cure acrylic resin. Each group was divided into 4 subgroups: unreinforced, reinforced with glass fibers, polyethylene fibers, and metal wire. All specimens were subjected to a 3-point bending test, and the flexural strength was calculated. Results: The group repaired with heat cure acrylic resin and reinforced with glass fiber showed the highest flexural strength; however, the group repaired with cold cure acrylic resin and reinforced with polyethylene fibers had the lowest flexural strength. There was no significant difference between the groups repaired with heat cure and cold cure acrylic resins without reinforcement. Conclusion: Repairing denture base with heat cure acrylic resin, reinforced with glass fibers increases the flexural strength of denture base.
Research
Full-text available
The aims of this study were to review five different explantation techniques for the removal of failing implants and to propose a practical clinical protocol. During a 10-year period, 95 implants were explanted from 81 patients. Explantation techniques used were the bur–forceps (BF), neo bur–elevator–forceps (hBEF), trephine drill (TD), high torque wrench (HTW), and scalpel–forceps (SF) techniques. The following parameters were analyzed: indications for explanation, site of implantation, and the type, diameter, and length of the implant removed. The most frequent indications for implant removal were peri-implantitis (n = 37) and crestal bone loss (n = 48). The posterior maxilla was the most frequent site of implant removal (n = 48). The longer implants were more frequently removed (n = 78). The majority of implants were removed after 1 year in function (n = 69). The BF/hBEF and SF techniques were found to be the most efficient. Explantation techniques appeared to be successful for the removal of failing implants. The BF/ hBEF and SF techniques demonstrated 100% success. The hBEF technique enabled safe insertion of a new implant in the same explantation site. The HTW technique appeared to be the most elegant technique with the highest predictability for insertion of another implant. An explantation protocol is proposed.
Article
Full-text available
The aims of this study were to review five different explantation techniques for the removal of failing implants and to propose a practical clinical protocol. During a 10-year period, 95 implants were explanted from 81 patients. Explantation techniques used were the bur-forceps (BF), neo bur-elevator-forceps (ηBEF), trephine drill (TD), high torque wrench (HTW), and scalpel-forceps (SF) techniques. The following parameters were analyzed: indications for explanation, site of implantation, and the type, diameter, and length of the implant removed. The most frequent indications for implant removal were peri-implantitis (n = 37) and crestal bone loss (n = 48). The posterior maxilla was the most frequent site of implant removal (n = 48). The longer implants were more frequently removed (n = 78). The majority of implants were removed after 1 year in function (n = 69). The BF/ηBEF and SF techniques were found to be the most efficient. Explantation techniques appeared to be successful for the removal of failing implants. The BF/ηBEF and SF techniques demonstrated 100% success. The ηBEF technique enabled safe insertion of a new implant in the same explantation site. The HTW technique appeared to be the most elegant technique with the highest predictability for insertion of another implant. An explantation protocol is proposed. © 2015 International Association of Oral and Maxillofacial Surgeons.
Article
Full-text available
The aim of this study was to evaluate retrospectively biologic and technical complications as well as clinical and radiographic outcomes of patients treated with 4 implants according to the All-on-4 protocol and followed up to 7 years of function. Data from 56 consecutive patients presenting complete edentulous jaw, aged 18 years or older, treated between January 2008 and December 2013, were evaluated. The outcomes were implant and prosthetic survival and success rates, any complications, and marginal bone loss (MBL). Two-hundred twenty-four implants were placed in 56 patients. During the entire follow-up, 1 maxillary implant but no prosthesis failed during the healing process. Fourteen patients experienced 1 complication each (10 technical, 4 biologic). The overall implant and prosthetic success rate was 98.2% and 82.1%, respectively. All complications were considered as minor and successfully resolved chairside. A mean MBL of 1.30 ±0.63 mm was observed at the last follow-up. Statistically significant difference was found for postextractive implants (0.79 ± 0.26) vs implants placed in healed sites (1.03 ±0.46; P = 0.024). Within the limits of the present study, the All-on-4 concept may be a valuable surgical and prosthetic option for the treatment of complete edentulous jaws. However, minor technical and biologic complications can occur. Further long-term prospective data with primary outcomes focused on success rates are needed.
Article
The aim of this study was to assess the effects of partial carbon or glass fiber reinforcement on the flexural properties of All-on-Four provisional fixed denture base resin. The carbon or glass fibers were woven (3% by weight) together in three strands and twisted and tightened between the two abutments in a figure-of-“8” pattern. Four types of specimens were fabricated for the three-point loading test. The interface between the denture base resin and fibers was examined using scanning electron microscopy (SEM). Reinforcement with carbon or glass fibers between two abutments significantly increased the flexural strength and flexural modulus. SEM revealed relatively continuous contact between the fibers and acrylic resin. The addition of carbon or glass fibers between two abutments placed on All-on-Four provisional fixed denture base resin may be clinically effective in preventing All-on-Four denture fracture and can provide several advantages for clinical use.
Article
Purpose: To retrospectively record the distal cantilever lengths (CL) of full-arch interim, all-acrylic resin prostheses used in an immediate occlusal loading protocol. Anterior/posterior (A/P) spreads were measured on master casts associated with the interim prostheses. Ratios were calculated (CL/AP). Prosthetic complications were recorded. The ratios and prosthetic complications were statistically compared and analyzed for statistical and clinical significance. Materials and methods: One hundred twenty-eight patients with 192 edentulous arches (109 maxillary; 83 mandibular; 190 arches were restored with 4 implants; 2 maxillary arches were restored with 5 implants) were treated. Seven hundred seventy implants (Brånemark System) from September 1, 2011, until August 31, 2013 were included in this report. Patients were treated and followed in a single private practice for up to 40 months. Implants had to have at least 35 Ncm of insertion torque to be immediately loaded. All implants were immediately loaded with full functional occlusions on the day the implants were placed. Interim, full-arch, all-acrylic resin prostheses were fabricated and placed into full functional occlusion following an All-on-Four protocol. Measurements of the distal cantilevered segments were made on the prostheses prior to insertion. A/P spreads were measured on the master casts made from abutment level impressions made on the day of surgery. Prosthetic complications (denture base fracture, cohesive/adhesive denture tooth fractures) were recorded in the charts as they occurred. All charts were reviewed for this report; no patients were lost to follow-up. Interim prosthetic repairs were analyzed by type (tooth or denture base), arch, gender, and location within the edentulous arches. Results: One patient experienced complete maxillary implant failure; the overall implant survival rate (SR) was 99.5% (766 of 770). Four hundred thirty of 434 maxillary implants and 336 of 336 mandibular implants survived for SRs of 99.1 and 100%, respectively. Thirty four of the 192 interim prostheses (17.7%) warranted at least one repair during treatment. The average cantilevered segments for the interim maxillary prostheses without prosthetic complications were 9.7 mm (right) and 9.5 mm (left). The average cantilevered segments for the repaired maxillary prostheses were 10.1 mm (right); 9.9 mm (left). The average cantilevered segments for the interim mandibular prostheses without prosthetic complications were 9.2 mm (right) and 9.3 mm (left). The average cantilevered segments for the repaired mandibular prostheses were 9.87 mm (right) and 9.18 mm (left). The average maxillary A/P spread was 18.4 mm; the average mandibular A/P spread was 17.3 mm. The average maxillary CL/AP spread ratios were 0.55 (right) and 0.53 (left); the average mandibular CL/AP spread ratios were 0.61 (right) and 0.57 (left). There were no statistical correlations between the CL/AP ratios and the frequency or type of prosthetic repairs recorded in this study. The ratios were statistically significant (p = 0.041) for mandibular prostheses with prosthetic complications: slightly greater CL/A-P ratios were noted. Conclusions: The results from this 2-year clinical retrospective analysis indicated that CL/AP ratios in the range of 0.5 to 0.6 generally resulted in successful interim prostheses during the time the interim prostheses were in function. The results of this investigation also revealed that 1 of 129 patients experienced implant failures; implants placed and restored on the same day with full-arch, screw-retained prostheses resulted in high clinical survival rates for implants and prostheses. The All-on-Four treatment protocol used in this study was a viable alternative to other implant loading/placement protocols for rehabilitating edentulous patients and resulted in minimal prosthetic complications.