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272 PART V ORALANDMAXILLOFACIALSURGERY
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67. How should tears of the sinus membrane be managed during sinus lift?
Tears over corticocancellous grafts will heal. Particulate grafts may be lost if they migrate through per-
forations. Small tears may not pose a problem because the membrane folds over itself as it is lifted.
Larger tears should be patched with a material such as Surgicel or Collatape.
68. How much native bone is required for immediate placement of implants with
sinus lift?
A minimum of 4 to 5 mm of alveolar bone.
69. What is the proper size of the window for a sinus lift?
The window for a maxillary sinus lift begins at the anterior aspect of the sinus and continues inferiorly
to several millimeters above the sinus floor. The window extends posteriorly approximately 20 mm.
The superior osteotomy is approximately 10 to 15 mm above the inferior osteotomy.
70. What is the desired thickness of a split-thickness skin graft (STSG)?
STSGs can be of varying thickness. An STSG is composed of the epidermis layer and part of the der-
mis layer. The STSG can be classified as thin, intermediate, or thick, based on the amount of dermis
included. STSGs are between 0.010 and 0.025 inch.
71. Which types of skin grafts contract the most? The least?
The thinner a skin graft, the more the contraction. A thin STSG contracts more than an intermediate
STSG,whichcontractsmorethanathickSTSG.Full-thicknessskingraftshardlycontractatall.
Primary contraction is caused by elastic fibers in the skin graft as soon as it has been cut. This
can be overcome when a graft is sutured in place. Secondary contraction begins about postoperative
day 10 and continues for up to 6 months.
72. What is plasmic imbibition?
Plasmic imbibition is the process by which a skin graft absorbs a plasma-like fluid from its underlying
recipient bed. It is absorbed into the capillary network by capillary action. This process is the initial
means of survival for a skin graft and continues for approximately 48 hours.
73. Does grafted skin most resemble the donor site or the recipient site?
Grafted skin maintains most of its original characteristics, except that sensation and sweating more
closely resemble the recipient site.
74. What are the goals of vestibuloplasty?
Vestibuloplasty, skin grafting, and floor of the mouth lowering increase the depth of the sulcus, which
helps control lateral displacement of a denture. The skin graft also provides attached tissue, which will
not be elevated by movement of the lip, cheeks, and tongue, providing a stable denture seating area.
Skin grafts provide more comfortable load-bearing tissue than mucosa. The mandibular resorption
rate beneath skin is probably slower.
75. What are the possible graft donor sites for vestibuloplasty?
• Skin
• Palatalmucosa
• Buccalmucosa
76. What are the advantages of using a stent to secure a graft in place for a
vestibuloplasty?
A stent can be used to adapt the skin with accuracy to any contour in the labiobuccal area and under-
cuts in the lingual area. A stent also provides additional graft stabilization and protects the graft from
food in the oral cavity.
77. What are the advantages of suturing a graft in place for a vestibuloplasty?
Patients are more comfortable without the stent. Stent construction and adaptation materials are not
necessary.
78. What is the lip-switch procedure?
The lip-switch procedure is a transpositional flap vestibuloplasty. An incision is made in the labial
mucosa. A thin mucosal flap is elevated, continuing into a supraperiosteal dissection on the anterior
aspect of the mandible to the crest of the ridge. The mucosal flap is sutured to the depth of the
vestibule covering the anterior aspect of the mandible, and the denuded tissue on the inner surface of
the lip heals by secondary intention. A modification transposes the lingually based mucosal flap with
an inferiorly based facial periosteal flap.
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79. What is submucous vestibuloplasty?
Submucous vestibuloplasty can be used for improvement of the maxillary vestibule in situations in
which the alveolar ridge resorption is not severe but mucosal and muscular attachments exist near
the crest of the ridge. Through a midline incision, submucosal and subperiosteal dissections are
performed. The tissue between these two tunnels is cut and allowed to retract. A splint is relined and
secured in place for 7 to 10 days.
80. How is floor of the mouth lowering performed?
An incision is made on the lingual aspect of the alveolus. A supraperiosteal dissection is carried
inferiorly, and the mylohyoid and genioglossus muscles are sharply dissected from their insertions.
No more than half the superior aspect of the genioglossus muscle should be released. The mucosal
margins are then sutured to the new depth, either with sutures passed externally or in a circummandibular fashion.
81. What is the minimum distance from the inferior border that the mentalis must
remain attached, during vestibuloplasty, to prevent a sagging chin?
A minimum of 10 mm of muscular tissue must remain attached to the vestibular periosteum in order
to avoid a sagging chin.
BiBliography
Dentoalveolar Surgery
Alling CC, 3rd (ed) Dentoalveolar surgery, Oral and maxillofacial surgery clinics of North America (vol 5). Philadelphia, 1993,
Saunders.
Dental trauma guide, International Association of Dental Traumatology, Accessed September 2014.
www.dentaltraumaguide.org.
Hupp JR, Ellis E, Tucker MR: Contemporary oral and maxillofacial surgery, ed 6, St Louis, 2014, Mosby/Elsevier.
Kiesselbach JE, Chamberlain JG: Clinical and anatomic observations on the relationship of the lingual nerve to the man-
dibular third molar region, J Oral Maxillofac Surg 42:565, 1984.
Laskin DM: Clinician’s handbook of oral and maxillofacial surgery, Carol Stream, Ill, 2011, Quintessence.
Lew D: Blood and blood products. In Kwon PH, Laskin DM, editors: Clinician’s manual of oral and maxillofacial surgery,
ed 3, Carol Stream, Ill, 2001, Quintessence.
Pogrel MA, Lee JS, Muff DF: Coronectomy: a technique to protect the inferior alveolar nerve, J Oral Maxillofac Surg
62:1447, 2004.
Todd DW, Roman A: Outpatient use of low-molecular weight heparin in an anticoagulated patient requiring oral surgery:
case report, J Oral Maxillofac Surg 59:1090, 2001.
Whitacre R: Removal of Teeth, ed 3, Seattle, 1983, Stoma Press.
Preprosthetic Surgery
Davis WH, Sailer HF: Preprosthetic surgery, Oral Maxillofac Surg Clin North Am 6:4, 1994.
FonsecaRJ: Oral and maxillofacial surgery, vol 7, St Louis, 2000, Saunders.
MacIntosh RB: Autogenous grafting in oral and maxillofacial surgery, Oral Maxillofac Surg Clin North Am 5:4, 1993.
Marx RE, Carlson ER, Eichstaedt RM, et al.: Platelet-rich plasma: growth factor enhancement for bone grafts, Oral Surg Oral
Med Oral Pathol Oral Radiol Endod 85:638–646, 1998.
Marx RE, Morales MJ: Morbidity from bone harvest in major jaw reconstruction: a randomized trial comparing the lateral
anterior and posterior approaches to the ilium, J Oral Maxillofac Surg 48:196–203, 1988.
Peterson LJ, Indresano AT, Marciani RD, et al.: Principles of oral and maxillofacial surgery, Philadelphia, 1992,
J.B. Lippincott.
DENTAL IMPLANTS
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George R. Deeb, Graham H. Wilson, Kenneth J. Benson
CHAPTER 26
1. What are the different dental implant categories?
Dental implants are divided into three categories based on their relationship to the oral tissues:
1. Subperiosteal
2. Endosteal
3. Transosseous
Endosteal implants are subdivided into root-form implants and plate-form or blade implants. Root-
form implants can be smooth, threaded, perforated, and solid or hollow, vented, coated, or textured.
Root-form implants are subdivided into the following categories including cylinder implants, screwdesigned implants, or combination of screw and cylinder implants. Currently, the most commonly used
implants are root-form implants. Only endosseous and transosseous implants are considered true
osseointegrated implants.
2. What is osseointegration?
Several definitions have been proposed over the years to describe a successful dental implant in the
human jaw. However, the most inclusive definition to date describes osseointegration as “a process
whereby clinically asymptomatic rigid fixation of alloplastic materials is achieved and maintained in
bone during functional loading.”
3. What criteria were used to determine the success of an implant before 1986?
Before 1986, the criteria for a successful implant were different from those used today. According
to the 1978 Harvard–National Institutes of Health (NIH) consensus conference on implantology, an
implant was considered successful despite the presence of one or more of the following clinical
features:
• Mobilityof<1mminanydirection
• Bonelossofnomorethanone-thirdoftheverticalheightoftheimplant
• Gingivalinammationamenabletotreatment
• Absenceofsymptoms,suchasinfection,numbness,pain,ormaxillarysinusornasalsymptoms
• Implantfunctionalfor5yearsin75%ofcases
4. What became the criteria for successful implants after 1986?
In 1986, with the introduction of osseointegration, the criteria for successful implants were revised:
• Implantclinicallyimmobile
• Noradiographicevidenceofanyperiimplantradiolucency
• Verticalbonelossof<0.2mmafterthefirstyearoffunction
• Absenceofanysymptoms,suchaspain,infection,numbness,ormaxillarysinusornasal
symptoms
• Successrateof85%after5yearsand80%after10years
5. When are dental implants indicated?
Dental implants are used to achieve rehabilitation of the oral and facial tissue after tooth loss with and
without bone loss, after jaw bone loss due to tumor resection, after tooth loss from trauma, and for
partially or completely congenitally missing teeth. More specifically, implants are used to achieve one
of the following purposes:
• Fixedrestorationofasingletoothormultipleteethinapartiallyedentulousjaw
• Retentionofaremovableprosthesisinapartiallyedentulousjaw
• Retentionofaprosthesisinacompletelyedentulousjaw
• Retentionofafixedprosthesisincompletelyedentulousmaxillaormandible
• Retentionofamaxillofacialprosthesisafterlossofjawbonefromtraumaoraftertumorresection
• Asafixturefororthodontictoothmovementwhenconventionalanchorageisnotfeasibleoris
cumbersome
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6. What are the advantages of a single implant for replacing a single tooth compared
to a conventional three-unit bridge?
• Highsuccessrate
• Decreasedriskofcariesortoothlossofabutmentteeth
• Decreasedriskofendodonticproblemswithabutmentteeth
• Betteraccessforhygiene
Fixedpartialdenturefailureratesmaybeashighas20%after3years,and50%at10years.
7. What are some advantages to implant-retained/supported prostheses compared
to conventional removable prostheses?
• Maintainbone.
• Improvephonetics.
• Improveretentionandstability.
• Improvemasticatoryperformance.
• Increaseprosthesissuccess.
• Improvepsychologicalhealth.
8. What are Brånemark’s surgical principles for ensuring osseous integration
of implants?
Brånemarkestablishedasetofsurgicalprinciplesbasedonanimalandhumanresearchthat,iffol-
lowed during implant placement, ensures osseointegration of the dental implants:
• Theimplantshouldbeplacedindirectcontactwiththebone.
• Implantsshouldbeinsertedinboneinasurgicallypreparedsite,usingagradedseriesofdrills
followedbyataprotatingat15rpm.
• Absolutetemperaturecontrolatthesurgicalsiteshouldnotexceed47°Ctominimizethermal
necrosis of bone adjacent to implant.
• Themucosashouldremainsuturedoverthenewlyinsertedimplant,andtheimplantshouldremain
functionless for 3 to 6 months.
• Atasecondstage(3to6monthslater),theimplantisexposedandanabutmentandtheimplant
are connected to the prosthesis. Consequently, loading of the implant is done only after the implant
is osseointegrated. This last principle has changed in the last few years by successfully loading
implants immediately after placement with no impact on the success rate.
9. How much space is needed between implants for successful integration?
Imagine that a square box is drawn around the implant. In the buccal-lingual dimension, a minimum of
0.5mmofboneisrequiredaroundtheimplant.Thereforeforastandard3.75-mmimplant,theoperator
wouldneedapproximately5mmofboneinthisdimension.Mesiodistally,thesame0.5mmisrequired
for implant survival. Prosthodontically, at least 3 mm is necessary on both sides of the implant to create
the proper emergence profile of a restoration. Consequently, the recommendation for distance between
implants for single-tooth restoration is 7 mm from the center of one implant to the other.
10. How much space is observed between implant and bone in an osseointegrated
titanium implant?
The chemical properties and the interface chemistry are determined by the oxide layer and not by the metal
oftheimplant.Thereforethedenseoxidefilmofatitaniumimplant,forexample,isabout100Åthick.
11. Describe one-stage placement, two-stage placement, and immediate provisional-
ization of dental implants.
In two-stage implant placement, the implant is placed and submerged for a period of time, and sec-
ondary surgery for uncovering of the implant is necessary. A single-stage implant placement includes
placement of a permucosal component, most often a healing abutment, at the time of implant place-
ment.Immediateprovisionalizationinvolvesplacementoftheimplant,placementofatemporaryor
permanent abutment, as well as a restoration.
12. How much is the surface area of an implant increased by increasing the diameter
of an implant compared with increasing its length?
Foreach0.25-mmincreaseinimplantdiameter,thereisa10%increaseinsurfacearea.Therefore
a1-mmincreaseindiameterincreasessurfaceareaby40%.Studieshaveshownthatforimplants
largerthan15to18mm,thereisnofurthersignificantbiomechanicaladvantage,regardlessof
implant diameter.
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Some authors have shown that increasing the length of an implant to more than 18 mm provides
no additional mechanical advantage and possibly increases the incidence of failure rate because of
the difficulty of adequately irrigating during the preparation of the site.
13. What major anatomic structures in the maxilla can affect implant placement? How
can these problems be overcome?
Intheposteriormaxilla,apneumatizationofthemaxillarysinuscanresultinadecreaseintheavail-
able bone in this region. This deficiency can be overcome by bone grafting of this region. If the interarch space is adequate for restoration (implant-to-crown ratio), a sinus-lift bone graft procedure is
indicated. However, if there is an excessive interarch space, onlay bone graft with or without sinus-lift
procedure is a better choice. Distraction osteogenesis both to increase the bone height and to close
the interarch space is another option when there is an increased interarch space.
In the anterior maxilla, bony defects are occasionally observed on the buccal surface, caused
either by traumatic extraction or by buccal concavity around the apical one-third of the root. These
defects must be treated before or during implant placement. Angulation of the implant to engage
existing bone often will result in an implant that is unable to receive a direct axial load and will be
more prone to failure after a restoration is placed.
14. What major anatomic structures in the mandible can affect implant placement?
How can these problems be overcome?
In the posterior mandible, the inferior alveolar nerve is one of the most common impediments to
implantplacement.Frequently,thereisinsufficientboneheighttoplaceevenan11.5-mmimplant
intheposteriormandiblewithouttheriskofnerveinjury.Remediesforthisproblemdependmostly
on restoration length and available interarch space. As in the maxilla, if there is sufficient interarch
space,thenervemustbesurgicallyrepositioned(lateralized)togainadequatebonelengthtoachieve
a proper crown-to-root ratio and anchorage for the implant. If there is excessive interarch space,
onlay bone grafting or distraction osteogenesis should be considered to gain vertical bone height and
decrease the interarch space before implant placement.
The lingual concavity of the mandible in the posterior and anterior regions is another anatomic
area to be considered during placement of mandibular implants. Computed tomography (CT) or plain
tomography should be considered if there is any question as to whether an implant can be placed
withoutperforatingtheconcavityandriskingimplantfailureordamagetothelingualnerve.
15. Is it necessary to have attached gingiva when placing implants?
Ideally, implants are more easily maintained if an adequate cuff (1 to 2 mm) of attached tissue is left
around the restoration. This does not mean, however, that attached tissue is necessary at the time
of placement. In the edentulous mandible, there is often a paucity of attached tissue at the time of
placement, and most patients have high mentalis muscle attachments that extend to the crest of the
remaining alveolus. At the time of placement, or at a later time but before uncovering the implant in a
two-stageimplantsystem,measurescanbetakentolowerthesemuscleattachments(lip-switchor
other vestibuloplasty procedures) to gain immobile tissue.
16. What are some tests to evaluate osseointegration at the time of implant
uncovering?
Torque testing can be done to test for osseointegration at the time of implant uncovering. Ideally, one
shouldbeabletoplaceaforceof10to20Ncmwithoutunscrewinganimplantifitissuccessfullyosseointegrated. Other clinical subjective signs of integration are percussion and immobility when placing a
fixturemountorimpressioncopingontheimplant.Whenalateralforceof5lbisapplied,nomovement
shouldbeseen.Horizontalmobilityof>1mmormovement<500gofforceindicatesafailedimplant.
Resonance frequency analysis is an easy, reliable, and noninvasive means of measuring implant
stability. The resonance frequency value is measured using a transducer that is mounted directly on
the fixture and displays the result as the implant stability quotient (ISQ). The ISQ is between 1 and
100,withahighervalueindicatingincreasedresonancefrequencyandstabilityoftheimplant.
17. What methods are used to uncover implants? Can a laser or electrocautery be used?
Conventionaluncoveringisdonewithascalpel.Ifthereisaminimalbandofkeratinizedtissue,an
incision is made to split this band, and the tissue is sutured to either side of the healing abutment.
Ifthereisadequateattachedimmobiletissue,apunchbiopsycanbeusedafterlocalizationofthe
implantwithaneedle.Laserscanalsobeused,butcaremustbetakentoavoidreectingenergyoff
the implant to the adjacent bone, which will cause irreversible thermal damage. Electrocautery can
alsobeusedcarefullywithouttouchingthefixturetoavoidtransmittingheatthroughoutthesocket.
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18. What preoperative radiographs are necessary for adequate work-up before
implant placement?
Panoramic and periapical radiographs are helpful and necessary, although they offer no informa-
tion regarding the internal anatomy of the alveolar process or residual ridge. In addition, they do
not permit accurate three-dimensional superimposition of a clinically verified radiopaque template,
which can be used as a surgical guide. Multiplanar reformatted CT can be used to obtain this information if it cannot be obtained easily by a combination of conventional radiographic techniques and
clinical exam.
19. Are magnetic resonance imaging (MRI) and CT scans contraindicated in a patient
with dental implants?
MRI and CT scans are not contraindicated in patients with pure titanium implants. Most CT scanners
can subtract titanium and other metals from the image and eliminate the scatter images.
20. Can you name some risk factors that may increase the failure rate and complications of implant placement?
• Smoking
• Uncontrolledsystemicdiseasesuchasdiabetesandhematologicdisorders;alsopatientswhoare
immunocompromised(e.g.,HIV,chemotherapy)
• Radiationtherapytotheregionplannedforimplantplacement
• Useofbisphosphonatesorotherantiresorptiveagents
• Existingpathologyintheareaplannedforimplantplacement(e.g.,maxillarysinuspathology)
• Parafunctionalhabit(e.g.,Bruxism)
21. What are the most common reasons for endosseous dental implant removal?
• Lackofintegration
• Surgicalmalposition
• Lackofbonesupport
• Psychiatricreasons
• Lossofbone
22. What are the possible complications of endosseous dental implants?
The most commonly reported reasons for dental implant failure are:
• Infection
• Perforationofthemaxillarysinusandnasalcavity
• Perforationofthelingualcortexofthemandible,andpossiblearterialinjury.Thismayresultin
troublesome hemorrhage that can compromise the airway.
• Lossofimplant
• Boneresorptionandlossoftheimplant
• Fractureofthemandible
• Damagetoadjacentteeth
• Nerveinjury
23. What is the long-term success rate of endosseous implants?
The5-yearcombinedsuccessrateofmaxillaryandmandibulardentalimplantsis94.6%.Albrektsson
etal.reportedmaxillaryimplantswithasuccessrateof84.9%for5to7years.Forirradiatedmaxilla,
thesuccessrateofimplantsis80%;ingraftedmaxilla,thesuccessrateis85%.
In large, long-term studies of mandibular and maxillary endosseous implants, the success rate
rangesfrom84%to97%.Specifically,themaxillaryimplantsuccessrateafter1yearis88%andafter
5to12yearsis84%.Inthemandible,the1-to2-yearsuccessrateis94%to97%,the5-to12-year
successrateis93%,andthe15-yearsuccessrateis91%.Thesuccessrateinthemandibleposterior
regionis91.5%andinthemaxillaryposteriorregionis82.9%,whereasthesuccessratesarehigher
intheanteriormandible,inthe94%to97%range.
24. What is the success rate of endosseous implants placed in an autogenous bone
graft site?
InastudybyKelleretal.,248commerciallypuretitaniumendosseousimplantswereplacedin54
consecutive patients who required bone grafting. Types of grafts included cortical, corticocancellous,
andparticulatebone.All74antralsitesreceivedablockgraft.Endosseousimplantsuccessoverthe
12-year period was 87%,andbonegraftsuccessreached100%.Ahigherlossofimplantsoccurredin
theLeFortIfracturegroupscomparedwithothergraftingapproaches.
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25. When is a transmandibular implant (TMI) indicated?
ATMIcanbeplacedinatotallyedentulousmandibleofanyboneheight.However,aTMIworkspar-
ticularlywellintheprostheticrestorationofaseverelyatrophicmandible(<12mmofbonevertically).
However, with the recent advances in endosseous implants, the need for and use of TMI has almost
been eliminated.
26. Is hand tightening of an abutment acceptable for immediate provisionalization?
Yes.However,handtighteningdoeshaveahighincidenceofscrewloosening.Todecreasethe
number of emergency patients with loose restorations, use of a calibrated mechanical torque wrench
isadvisedtoapplyappropriatetightening.Mostauthorsrecommendapplying35Ncmtotightenthe
abutment. In general, following the individual manufacturer’s specifications will decrease loosening.
27. What are three key features for successful implant treatment for single-tooth
edentulism?
1. Primary stability
2. Oxidizedimplantsurfaces
3. Light centric occlusion only and removal of lateral excursives on the restoration
28. Which type of implant surface has shown better bone healing response: machine
or oxidized surface implants?
Multiplestudiesshowanincreasedresponseofbonetooxidizedsurfaces.Thisimplantfeaturehas
allowedquickersecondarystabilitybecauseosseointegrationisquicker.
29. What considerations should be made when planning implants in an irradiated
patient?
Aswithanyotherdentoalveolarprocedure,onemustknowtheirradiatedfieldanddose,anatomic
considerations with amount of bone available, and time period the radiation was delivered. Dose is a
keyfactor,with55Gyandgreaterbeinganamountthatistraditionallythelevelatwhichtreatment
should be given with the most caution (particularly in the mandible).
Hyperbaric oxygen (HBO) can be used as an adjunctive treatment for implant rehabilitation.
ThestandardHBOprotocol(20divesbeforeimplantsurgeryand10divespostimplantplacement)
providesimprovedbonehealingandturnoverwithenhancedangiogenesisandneovascularizationin
theirradiatedtissues.Also,onemustknowwheretheradiationwasdelivered,becausesomeareas
ultimately have less radiation delivered than others and treatment can be planned accordingly, with
more implants delivered in a less radiated area of the mandible/maxilla. Dosimetry reports, which
can provide information regarding the dose received in specific areas, can often be obtained from the
patient’s radiation oncologist. This information is extremely valuable in treatment planning location of
implants and prevention of implant failure as well as osteoradionecrosis.
Many studies indicate successful integration of endosseous implants in irradiated fields even
withouttheuseofHBOtherapy.AstudybyAndersonetal.demonstratesasuccessrateof97.8%for
endosseousimplantsplacedintoanirradiatedfield.Thisstudyevaluated90implantsplacedin15
patientsfortreatmentofmalignanciesinthemaxillofacialregionwithradiationdosesrangingfrom44
to68cGy.OtherstudiesshowsimilarratesofsuccesswithouttheuseofHBO.
30. What variables increase success in immediate implant placement?
Patientswiththickgingivalbiotyperespondwithamorepredictablefinalgingivalmarginlevel,and
their incisions tend to heal with less scarring. Patients with thin gingival biotype tend to respond to
surgicalinsultsandbonelosswithhigherincidenceofgingivalrecession.Aaplesstechniqueis
advised, and vertical releasing incisions should be avoided, especially in patients with a thin biotype.
Cosynetal.demonstrateda96%implantsurvivalratewithmeanfacialgingivalmarginrecessionof
0.34mmover3yearswithimmediateimplantplacementandtemporizationinthemaxillainpatients
withathickgingivalbiotypeandnolabialbonedefects.
Adequate crestal bone levels should be verified with preoperative periodontal probing. If there
is a defect in the labial bone, grafting should be completed and implant placement delayed until
adequate bony architecture is restored.
Implantsintheestheticzonemustengagebonepalatalandapicaltotheextractionsocket,
especiallyifimmediateprovisionalizationisplanned.Theaxisoftheimplantsshouldbealongthe
cingulum or slightly palatal to the incisal edge. Cone beam CT can readily offer information regarding
bone apical and palatal to the existing tooth in planning for implant placement, as well as labial bone
thickness.
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31. What are some key components to planning implants in the esthetic zone?
• Assessmentofthesmileline.Agreaterpercentageoffemalespossessahighsmileline,posinga
greaterchallengeforsuccessfulimplanttherapyintheestheticzone.
• Gingivalbiotype.Patientswithathingingivalbiotypemaybeconsideredforconnectivetissue
graftingtoachieveathickerbiotype.Gingivalbiotypehasimplicationsonone-versustwo-stage
surgery, as well as incision design for implant placement.
• Theinterdentalpapillacommonlyfillstheinterproximalspacewhentheverticaldistancefrom
theinterproximalcrowncontacttointerseptalboneis5mmorless.Ifthedistanceisincreasedto
6mm,thenthepapillafailstofillthespace40%ofthetime.
• Theideallabialmidcrestalbonepositionshouldbe2mmapicaltothefacialcemento-enamel
junction (CEJ) of the adjacent teeth. The implant platform should be 3 mm below the facial free
gingival margin. Placement of the platform at this level will allow for development of proper emer-
genceprofile,adequatetissuethicknesstocoverthedarkersurfaceoftitanium,andpreventionof
periodontalpocketformationandgingivalrecession.
• Implantplacementshouldbeatleast1.5mmfromadjacenttoothrootstopreventbonelosson
both the implant and tooth related to the microgap or biologic width, as well as to prevent potential
problems with interproximal esthetics. The distance between adjacent implants should be a minimum of 3 mm. The faciopalatal width should be at least 2 mm greater than the implant diameter,
andideallyatleast1.5mmofboneonthefacialaspectoftheimplantshouldbepresent.Ridge
augmentation for increased width can be completed prior to implant placement, or at the time of
implantplacementwithsuccess.Greatersuccesswithaugmentationatthetimeofimplantplacement occurs if there is no dehiscence of the implant.
• Themesiodistaldimensionofthemissingtoothmustbeconsideredwhenselectingthepropersize
implant. The average mesiodistal dimension of a central incisor is 8.6 mm for a man and 8.1 mm
for a woman. Prosthodontically, at least 3 mm is necessary on both sides of the implant to create
the proper emergence profile of a restoration.
32. What factors should be considered when using cement versus screw-retained
provisionals?
Screw-retained provisionals have the advantage of being easily retrievable and are indicated when
abutmentheightislessthan5mmwhereacementedrestorationwouldnotprovideadequateresistanceandretention.Cementedrestorationslackscrewholesthatcandecreasethephysicalstrength
of the restoration, as well as compromise esthetics if they are buccally located. Another advantage
withcementedprovisionalrestorationsisthelackofscrewholesinareasofpossibleopposingocclusalcontacts.Screw-retainedrestorationsalsoposetheriskofscrewloosening,stretching,orfracture
if there is offset loading of enough magnitude to overcome the retentive force of the screw. There is
alwaystheriskofgingivalinammationandinfectiontoanyresidualcementthatisnotremovedafter
cementation of the provisional. There is no significant difference in implant survival or crown loss in
the use of cemented versus screw-retained restorations.
33. What are indications for zygoma implants, quad zygoma implants, and nasopalatine implants?
Zygomaimplantsarethreadedtitaniumimplantsavailableinlengthsupto55mm.Primarystabilityis
achievedbyengagingthecorticesofthealveolarridgecrest,themaxillarysinusoorandroof,and
thesuperiorborderofthezygoma.Zygomaimplantswereinitiallyusedforanchorageofobturator
prostheses in patients with significant defects after ablative surgery or traumatic injuries and are still
used today for this purpose. Zygoma implants were later applied to cases where vertical onlay grafting
hadfailed.Bilateralsinglezygomaimplantsinconjunctionwithanteriorlyplacedimplantshaveproven
to be a successful alternative to extensive onlay grafting of the severely atrophic posterior maxilla,
reducing or eliminating donor site morbidity and decreasing treatment and recovery time.
Therecommendedprotocolisplacementofbilateralsinglezygomaticimplantsincombina-
tion with two to four anteriorly placed, standard endosseous implants. Prosthesis options include
an implant-supported, full-arch fixed-removable prosthesis or a fixed prosthesis. The use of the
zygomaticimplantscanreducethenumberofimplantsneededascomparedtoaconventionaleight-
implant-supported fixed prosthesis. CT scans should be used to verify appropriate morphologic bone
structureinthezygoma,maxillarysinus,andalveolus.Immediatefabricationofatemporarycrossarch–archbarisnecessaryatthetimeofexposuretoensurecross-archstabilization.
In the severely atrophic maxilla where there is insufficient bone between the nasal cavity and
maxillarysinusandextensivegraftingiscontraindicated,theuseoftwozygomaticimplantsbilaterally
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canbeconsideredasanalternativeoption.Theanteriorzygomaimplantmaybeengagedintothe
anterior rim of the lateral wall of the orbit.
The incisive canal may be used to insert an implant for added support for an overdenture in the
caseofanatrophicmaxilla.Thelengthoftheincisivecanalrangesfrom4to26mmandisusually
4to6mmindiameteratthecrestand4mmattheapex.Reectionofpalataltissueandremoval
of the nasopalatine nerve and branch of the greater palatine artery rarely cause complications with
bleeding or significant sensory deficits.
34. What are some implant options for treatment of the edentulous maxilla
and mandible?
Placement of at least four implants in the anterior maxilla is recommended for an implant-retained
overdenture, as fewer than four implants will not resist the forces placed upon them. Implants are ideally placed bilaterally in the canine region and in the second premolar region to provide adequate A-P
spread. Additional implants should be considered at the central incisor, lateral incisor, or incisive canal
foradditionalretention,especiallygiventhatfailureofoneoutoffourimplantsmaylikelycompromise
restorability. Posterior support is provided by the denture base and palatal coverage should be similar
to a complete denture. This concept of implants placed anterior to the maxillary sinus eliminates the
needforsinusaugmentation.Implantsshouldbeaminimumof9mminlengthand3.5mmindiameter. Implants at the premolar site may be angled anteriorly to avoid violation of the maxillary sinus
butmustbewithin30degreesofdrawwiththeotherimplants.Kieneretal.demonstrated95.5%
implantsurvivaland95%denturestabilitywithoverdenturesretainedwithfourtosiximplants.
If the patient desires a palateless prosthesis, six to eight implants may be placed and restored
with a fixed implant-supported or removable prosthesis. Implants must be placed posteriorly for
support. Maxillary sinus grafting may be indicated in these patients. Cone Beam CT (CBCT) scans can
provide the necessary information including bony architecture, possible need for sinus or ridge augmentation, status of the sinus membrane, and presence of septae. A surgical guide constructed based
on both adequate bone to accommodate the implants as well as the design of the planned restoration
should be used to facilitate proper placement of the implants.
The edentulous mandible with bilateral posterior vertical alveolar ridge atrophy is a com-
monclinicalscenariothatmakesplacementofposteriorimplantsdifficultwithoutsignificantridge
augmentation that is not possible or desired in many cases. A minimum of two implants is necessary
for support of an implant-retained, tissue-supported prosthesis. It is best to place these as far apart
ontheridgeaspossiblewhileavoidingthementalnerve.TheAll-on-4conceptrestoredwithfixedfullarchprostheseshasbeendemonstratedtobeaviabletreatmentoptionwith94.8%implantsurvival
rateat10years,andprosthesessurvivalrateof99.2%.
35. Are antibiotics indicated when placing a single implant?
A single preoperative dose of systemic antibiotic has been shown to reduce implant failure rate when
controlled with a placebo group that did not receive an antibiotic. Systemic antibiotics have not,
however, demonstrated a significant difference in infection rate. Existing studies have been unable
to demonstrate a significant difference in prevention of implant failure or postoperative infection with
various postoperative antibiotic regimens.
36. What are some modalities for management of periimplantitis?
Periimplantitisisaninammatoryprocessofthetissuesaroundanosseointegratedimplantinfunc-
tion that results in loss of the supporting bone. Presence of plaque, bleeding on probing, periimplant
pocketing,radiographicboneloss,andpurulentexudateareindicativeofperiimplantitis.Themost
common bacteria species found are anaerobic, gram-negative rods. Common organisms include
Porphyromonas gingivalis, Porphyromonas intermedia, and Actinobacillus actinomycetemcomitans.
Commonly used treatment modalities include antiseptic treatment, systemic antibiotics,
mechanical debridement, and guided tissue regeneration.
Antiseptictreatmentconsistsof0.1%to0.2%chlorhexidinegluconatefor2to4weeks.Systemicantibioticscanbeutilizedespeciallyifpurulenceisfoundandisdirectedtowardthecommonly
foundanaerobic,gram-negativerods.Metronidazoleisoftentheantibioticofchoiceandcanbe
combined with Amoxicillin.
There have been several techniques proposed for decontamination of the implant surface during
debridement and regenerative procedures. Chlorhexidine gluconate application has been described
and has produced variable results. Diode laser decontamination as an adjunct to conventional
treatment of periimplantitis has been shown to increase implant survival. The air-powder abrasive
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technique or grit blasting has also been described in the literature, and several studies have shown no
significant difference in success when compared to laser decontamination.
Nd:YAGlasersusedatalowpulseenergyhavedemonstratedtheabilitytodecreasebacterial
load and result in no damage to the implant surface when cooling devices are used. The LAPIP (Laser
Assisted Periimplantitis Procedure) is a modification of the LANAP (Laser Assisted New Attachment
Protocol)inthatitisappliedtoimplants.Theprocedureinvolvesuseofthelasertoremovedinamed
sulculartissueanddecontaminatetheimplantsurface,followedbyuseofEMSpiezoscaler.Theresult
is decontamination of the implant surface with a blot clot that seals off the sulcus and prevents epithelial
downgrowth.
37. What factors should be considered for immediate loading?
Patients who are transitioning from a dentate to edentulous state may benefit functionally and
psychologicallyfromimmediatelyloadedrestoration.Factorsthatcauseinstabilityorsorenesswith
conventionaldenturessuchashighmuscleattachments,severegagreex,retrudedtongue,and
compromised hard and soft tissue anatomy should alert the clinician to explore the possibility of an
immediately loaded restorative option.
Patient-related factors that would compromise either implant stability or wound healing must be
considered.Examplesofthesefactorsincludeosteoporosis,diabetes,heavysmoking(>20cigarettes/
day),headandneckradiation,currentchemotherapyorsteroids,treatmentwithbisphosphonatesor
other antiresorptive agents, and parafunctional habits such as bruxism or clenching. Quality of the
bone will also determine implant success as the dense type II bone of the anterior mandible increases
primary stability and success in immediate loading.
Implantsofatleast10mminlengtharerecommendedwhenimmediateloadingisconsidered.
A minimum of four implants in the anterior mandible is required. If only four implants are to be
used, the posteriormost implants may be angled posteriorly to avoid the inferior alveolar nerve and
increaseA-Pspreadtoaminimumof10mm,whichwillpreventrockingofthedenture.Noposterior
cantileversshouldbeused,asrockingoftheprosthesisandresultanttorqueingoftheimplantsmay
occur. If possible, additional implants should be considered as they provide the advantages of superior
load distribution among implants, and extra support should one or more of the implants not obtain
adequate primary stability at insertion and require submergence or removal that may eliminate the
possibility of immediate loading.
A minimum of six implants for a maxillary fixed implant-supported prosthesis is required. Ideally,
additional implants are placed given the decreased bone quality found in the maxilla. As with the mandible, posterior cantilevers should be avoided, and additional implants should be included if possible.
Initialimplantstabilityiscriticalandshouldideallymeasurebetween40and65Ncm,anda
minimumof20Ncm.
38. What are some advantages and disadvantages of wide diameter implants?
Advantages include:
• Canbeusedasarescueimplantwhennarrowerimplantfailstogainadequatestability
• Canbeutilizedforimmediateimplants
• Increasedloadingadvantageduetoincreasedsurfaceareaandcompensateforpoorbonedensity
• Minimizecantileversforangledimplants
• Improveemergenceprofile
• Decreasescrewlooseningandminimizecomponentfracture
Disadvantages of wide diameter implants include:
• Increasedsurgicalfailurerate
• Moreeasilyplacedtooclosetoadjacentteethorimplants
• Mayresultindecreasedbuccalbonethicknessthatcanresultingingivalrecessionorvisualization
ofthedarkcoloroftheimplantthroughgingiva
39. What are some challenges and disadvantages of placing a mandibular second
molar implant?
• Highbiteforcethatcanresultinincreasedforceontheimplant,surroundingbone,abutment,
and screw, and the coronal restoration itself
• Relativelyhigherpositionofinferioralveolarcanalatthatsite
• Difficultaccesstoperformadequatehygiene
• Limitedaccessforcorrectimplantbodypositionandabutmentscrewplacement
• Thesecondmolarcontributesasmallpercentagetooverallchewingefficiency.
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