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Simultaneous implant placement with ridge augmentation using an

autogenous bone ring transplant

Article · April 2016

DOI: 10.1016/j.ijom.2015.11.001

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Clinical Paper

Pre-Implant Surgery

Int. J. Oral Maxillofac. Surg. 2016; 45: 535–544http://dx.doi.org/10.1016/j.ijom.2015.11.001, available online at http://www.sciencedirect.com

Simultaneous implantplacement with ridgeaugmentation using anautogenous bone ringtransplantM. Omara, N. Abdelwahed, M. Ahmed, M. Hindy: Simultaneous implant placementwith ridge augmentation using an autogenous bone ring transplant. Int. J. OralMaxillofac. Surg. 2016; 45: 535–544. # 2015 International Association of Oral andMaxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Abstract. The severely defective socket, in which implant placement within theremaining bone will result in a significantly off-axis implant position, precludesimmediate implant placement and requires bone grafting as an initial surgicalintervention. The aims of this study were to evaluate autogenous chin bone ringconsolidation after the augmentation of severely defective sockets and theclinical application of these rings in the premolar–molar region withsimultaneous implant placement in a one-stage procedure. Ten patients with12 defective sockets were included. Sockets were prepared with a trephine bur.Bone rings with a tapped implant osteotomy were harvested from the chin with alarger trephine bur. Bone rings were fitted in the prepared sockets. An implantdrill was used to prepare the bone apical to the ring through its centralosteotomy. Implants were screwed through the rings and the apical bone.Patients were examined clinically and radiographically immediately and at6 months postoperative. Crestal bone changes were measured and evaluatedstatistically. All grafted sockets showed bone healing with no significant crestalbone resorption and no infection; only one ring showed dehiscence, whichhealed during the follow-up period. All implants showed radiographic evidenceof osseointegration. The autogenous chin bone ring augmentation technique wasfound to be a reliable alternative method for the management of severelydefective sockets.

0901-5027/040535 + 010 # 2015 International Association of Oral and Maxillofacial Surge

M.Omara1, N. Abdelwahed2,M.Ahmed1, M.Hindy1

1Oral and Maxillofacial Surgery Department,Faculty of Oral and Dental Medicine, CairoUniversity, Cairo, Egypt; 2Oral andMaxillofacial Radiology Department, Facultyof Oral and Dental Medicine, Cairo University,Cairo, Egypt

Key words: ridge augmentation; bone ring;immediate implant.

Accepted for publication 4 November 2015Available online 28 November 2015

Defective sockets resulting from eitherperiodontal disease or surgical traumaduring extraction may have an insufficient

quantity of bone for successful implantplacement. Several classifications ofpost-extraction sockets in relation to

immediate implant placement have beenreviewed in the literature; Salama andSalama have classified extraction sockets

ons. Published by Elsevier Ltd. All rights reserved.

536 Omara et al.

into four classes according to the degree ofseverity of the buccal wall defects.1

A number of techniques have been de-scribed for the augmentation of defectivesockets for implant placement either in asimultaneous approach or a consecutiveapproach. These include socket preserva-tion, guided bone regeneration, and local-ized horizontal ridge augmentation usingtitanium mesh and onlay bone grafting.2–6

Socket preservation and guided bone re-generation have shown successful resultsin immediate implant placement for class Iand class II sockets of the Salama classi-fication.7 However, sockets of class III andclass IV are severely compromised, withpartial or total loss of the buccal plate ofbone, and implant placement within theremaining bone would result in a signifi-cantly off-axis implant position. In suchcases, immediate bone grafting withdelayed implant placement has been nec-essary to solve this problem.1

Autogenous corticocancellous chinbone grafts, either in the form of blocksor particulates, have been used successful-ly for the augmentation of localized alve-olar defects. There is experimentalevidence that intramembranous bonegrafts undergo less resorption than endo-chondral grafts when used in an onlaytechnique, based on the more rapid revas-cularization and similar embryonic origin(ectomesenchyme) of the donor and recip-ient sites, which enhance early healing.8–

10 Several studies have reported the use ofa trephine bur in the chin region for ridgeaugmentation. These have shown excel-lent results in relation to implant successand survival rates, with minor complica-tions in terms of damage to the localanatomical structures such as the teeth,nerves, muscles, and vasculature and in-fection in the donor site area. It has alsobeen stated that incisions in the labialvestibule rather than a sulcular approachallows preservation of the crestal bone anda more secure closure with reapproxima-tion of the mentalis muscle, resulting in alower risk of chin ptosis.11–18

The chin bone disc was first introducedto the surgical field by Watzak et al. for thebony closure of oro-antral fistulas.19 Thechin bone disc was recently modified to aring shape for the three-dimensional aug-mentation of defective sockets in the max-illary incisor region with simultaneousimplant placement; this technique provedsuccessful in bone augmentation and im-plant integration.20–22

The aims of this study were to evaluatethe consolidation of autogenous chin bonerings radiographically after three-dimen-sional augmentation of severely defective

sockets and the clinical application ofthese rings in the premolar–molar regionwith simultaneous implant placement in aone-stage procedure.

Materials and methods

Inclusion and exclusion criteria

A prospective study was conducted on aconsecutive series of 10 patients. All se-lected patients had fresh defective extrac-tion sockets in the mandibular premolar–molar region in which the buccal bone wasseverely compromised and implant place-ment within the remaining bone wouldhave resulted in a significantly off-axisimplant position. The alveolar bone sur-rounding the extraction sockets was defec-tive either due to periodontal disease ortraumatic extraction.

Patients with any systemic disease thatcould affect bone healing were excludedfrom the study.

Materials

Schilli Implantology Circle implants wereused in this study (SIC invent AG, Basel,Switzerland). Three types of implant drillwere employed: classical, crestal, and tap-ping. The trephine burs utilized in thisstudy were supplied with diameters (inter-nal diameters) of 3.0 mm (2.3 mm),4.0 mm (3.3 mm), 5.0 mm (4.2 mm),6.0 mm (5.2 mm), 7.0 mm (6.1 mm),8.0 mm (7.1 mm), 9.0 mm (8.0 mm), and10.0 mm (9.0 mm) (Dentium Co., Ltd,Gyeonggi-do, Korea).

Preoperative preparation and

radiographic examination

A thorough preoperative assessment ofall patients was carried out, includinghistory-taking and clinical and radio-graphic examinations.

Cone beam computed tomography(CBCT) (SCANORA 3D with Auto-Switch; Soredex, Helsinki, Finland) withexposure parameters of 85 kVp, 15 mA,and 6 cm field of view (FOV), was per-formed to determine the following: (1)linear measurements of the defective sock-et (recipient site) including its width,depth, and height, the amount of remain-ing bony surfaces, the amount of remain-ing apical bone, and its relationship to themandibular canal; (2) linear measurementsof the chin area as a donor site to identifythe area from which the graft could beharvested to meet the socket dimensions(width, depth, and height), without harmingthe adjacent vital structures.

The measurements were obtained usingthe following protocol23,24: (1) The OnDe-mand software MPR screen (multiplanarreformatting) was chosen for interfacing(OnDemand3D software, version 1.0.9;Cybermed Inc., Korea). (2) Adjustmentswere made to the orientation axis so thatthe axial cut was made parallel to theocclusal plane at the alveolar crest level.(3) Adjustments were made for the coronalcut by rotation of the axial image until theorientation axis was perpendicular to thebuccal cortex. (4) Adjustments were madesuch that the orientation axis of the sagittalcut was midway between the buccal andlingual cortices. (5) Measurements of thebuccolingual dimension were done onthe coronal section, measurements of thecraniocaudal dimension on the sagittalsection, and measurements of the mesio-distal dimension on the axial section. (6)The measurements were done along theorientation axis to ensure standardizationof the procedure. The slices revealingthe maximum dimensions of the defectivesocket, as well as those revealing themaximum dimensions of available boneat the donor site, were used for the mea-surements (Fig. 1).

Surgical procedure

All patients were instructed to use povi-done iodine mouth rinse (Betadine) beforethe surgical procedures. All procedureswere carried out under inferior alveolarnerve block anaesthesia with mepivacainehydrochloride and 1:200,000 adrenalinesolution (Scandonest 2%; Septodont,France).

A three-line pyramidal flap was incisedaround the defective socket with subse-quent reflection of a full thickness buccalmucoperiosteal flap. A minimal lingualreflection was performed for better expo-sure of the defective socket walls. Thesocket was prepared with a trephine burof outer diameter similar to the socketdiameter, guided by the preoperative planof ridge augmentation and the selectedimplant diameter and length (Fig. 2).

In the chin region, an intraoral unilateralsmall vestibular incision was made 3 mmbelow the attached gingiva. Then the flapwas dissected and reflected with partialpreservation of the muscle attachment.Based on the preoperative CBCT planning,the selected chin area was outlined mono-cortically with a trephine bur of sequential-ly larger diameter than that utilized inthe preparation of the socket, creating whatis called a chin disc (Fig. 3). An implantosteotomy was performed in the centreof this disc utilizing successive drills

Ridge augmentation with bone ring transplant 537

Fig. 1. Snapshot of the MPR (multiplanar reformatting) screen showing the preoperative assessment of defect dimensions. (A) Depth as thebuccolingual dimension in the coronal slice. (B) Length as the craniocaudal dimension in the sagittal slice. (C) Width as the mesiodistal dimensionin the axial slice. (D) Three-dimensional reconstruction of the defect area. The relationship to the canal is also evident (yellow arrows).

corresponding to the planned implantlength and diameter, with preservation ofat least 2 mm of normal intact bone aroundthe implant osteotomy. The central osteot-omy was then tapped using a special tap-ping drill through the entire length of thebone ring to prevent it from fracturing at thestage of implant installation (Fig. 4A andB). Harvesting of the bone ring was com-pleted bicortically using the same trephinebur that was used to outline it. The trephinebur was penetrated into the bone, and then

Fig. 2. Clinical photograph showing the prep-aration of the defective socket using a trephinebur.

smooth cutting was possible. To avoidchoking of bone inside the trephine bur,the trephine bur was pulled up and down.Adequate cooling and a low speed of 2000–3000 rpm are recommended to avoid heatdamage to the bone.6,12 Finally, the entirering was either pulled out simultaneouslywith the trephine bur during its withdrawal,or was removed with the aid of the tappingdrill (Fig. 4C and D). The harvested ringwas kept in normal saline and the flap wasclosed tightly in layers.

The customized bone ring was intro-duced into the prepared defective socketunder delicate pressure utilizing a smallbone mallet, augmenting it three-dimen-sionally; the ring was positioned such that

Fig. 3. Clinical photograph showing the out-lined bone graft.

it was 1–2 mm above the adjacent socketwalls to compensate for the anticipatedbone resorption (Fig. 5A). After ringplacement and immobilization using apickle fork, the final implant drill wasintroduced through the central osteotomyof the bone ring to prepare the remainingapical bone of the socket for at least 3 mm.The implant was then screwed passivelythrough the tapped central osteotomy ofthe harvested ring and firmly into theprepared bone apical to the ring using atorque ratchet. The platform of the implantwas positioned 1 mm below the surface ofthe ring to compensate for the anticipatedcrestal bone resorption. Finally, the cov-ering screw was secured and the ringmargin was rounded using a small egg-shaped bur. The flap was relaxed throughscoring of the periosteum and then ad-vanced and closed (Fig. 5B).

Postoperative instructions

After closure of the wound, a pressureband was applied to the chin and cheekareas for 48 h postoperatively. Thepatients were then instructed to applyice-packs over the chin and cheek areafor 20 min every hour for 6 h postopera-tively and to rinse their mouth with warmsaline solution starting on the second day

538 Omara et al.

Fig. 4. Clinical photographs showing (A) preparation of the central osteotomy with successiveimplant drills; (B) preparation of the central osteotomy using the final tapping drill; (C) ringwithdrawal with the aid of the final tapping drill; (D) complete withdrawal of the ring within thetrephine bur.

after surgery, three times per day duringthe first week postoperative. The patientswere kept on a soft diet for the first 48 h.Postoperative antibiotic, analgesic, andanti-inflammatory drugs were prescribedfor 5–7 days. Postoperative follow-up toevaluate wound healing at both the donorand recipient site was carried out everyday for the first week and then everymonth for 6 months. Also all patients werechecked for the presence or absence of

Fig. 5. Clinical photographs showing (A) the boaugmenting the socket and its defective walls iinside the bone ring.

pain, numbness, swelling, infection, hae-matoma, and bleeding at both the donorand recipient site.

Postoperative radiographic assessment

During the follow-up period, CBCT scanswere obtained immediately (within 1week) and 6 months postoperative forthe measurement of crestal bone height,bone density at the ring–implant interface,

ne ring after placement in the prepared socket,n three dimensions; (B) the implant installed

and bone density at the ring–alveolusinterface.

Protocol for image (slice) adjustment

Using the OnDemand software, the im-plant was used as a reference point. In thecoronal section (showing the buccolingualdimension), the orientation axis of thesagittal slice was adjusted to coincide withthe long axis of the implant and bisect it.The orientation axis of the axial slice wasadjusted to be at the level of the implantapical end and at a right angle to its longaxis (tangential to the implant apical end).

In the sagittal section (showing themesiodistal dimension), the orientationaxis of the coronal slice was adjusted tocoincide with the long axis of the implantand bisect it. The orientation axis of theaxial slice had already been adjusted inthe previous step to be at the level of theimplant apical end and at a right angle toits long axis.

Measuring the crestal bone height

In the coronal section, a straight line wasdrawn just parallel to the implant long axisfrom the crest of the bone ring buccally tothe point of intersection with the axialorientation axis and perpendicular to it.The height obtained was recorded in milli-metres. The same process was repeated forthe lingual side.

In the sagittal section, a straight line wasdrawn just parallel to the implant long axisfrom the crest of the bone ring mesially tothe point of intersection with the axialorientation axis and perpendicular to it.The height obtained was recorded in milli-metres. The same process was repeated forthe distal side.

The measurements obtained from theimmediate postoperative CBCT scanwere compared to those obtained fromthe CBCT scan done at 6 months postop-erative to evaluate the amount of crestalbone resorption (Fig. 6).

Measuring bone density at the ring–alveolus interface

This applied to the mesiodistal aspectsonly due to the buccal wall being severelydefective in all cases, as mentioned abovein the inclusion criteria.

In the sagittal section, a straight line wasdrawn just parallel to the bone ring at theline of the interface between the alveolarbone and the ring mesially; the mean bonedensity obtained was recorded in Houns-field units (HU) (making use of the regionof interest (ROI) tool included in the

Ridge augmentation with bone ring transplant 539

Fig. 6. Snapshot of the MPR (multiplanar reformatting) screen showing the postoperative assessment of crestal bone height. (A) Heightmeasurements for both the buccal and lingual aspects. (B) Height measurements for both the mesial and distal aspects. (C) Adjusted orientationaxes in the axial slice. (D) Three-dimensional reconstruction of the grafted bone ring.

software). The same process was repeatedfor the distal side.

The measurements obtained from theimmediate postoperative CBCT scan werecompared to those obtained from theCBCT scan done at 6 months postopera-tive to evaluate the improvement in heal-ing of the bone ring with the adjacentalveolar bone (Fig. 7).

Measuring bone density at the ring–implant interface

In the coronal section, a straight line wasdrawn just parallel to the implant from thecrest of the bone ring buccally to the apicalend of the ring; the mean bone densityobtained was recorded in HU (making useof the ROI tool present in the software).The same process was repeated for thelingual side.

In the sagittal section, a straight line wasdrawn just parallel to the implant from thecrest of the bone ring mesially to the apicalring end; the mean bone density obtainedwas recorded in HU (making use of theROI tool present in the software). Thesame process was repeated for the distalside (Fig. 7).

Statistical analysis

All data were subjected to statistical anal-ysis. The statistical analysis was per-formed using IBM SPSS version 20.0software (IBM Corp., Armonk, NY,USA). Data were represented as the mean� standard deviation (SD). The one-sam-ple Kolmogorov–Smirnov test was used toexamine the normality of the data distri-bution. The one-sample t-test was used tocompare specific variables to a constantvalue. The paired-sample t-test was usedto compare scale data within the studiedgroup of patients.

Prosthetic phase

Six months postoperatively, a minimalcrestal incision was performed under localanaesthesia and a small flap was reflectedto expose the covering screw. The healingabutment was then secured and the flapclosed around it to give a natural gingivalappearance after healing. After 1 week thehealing abutment was removed and thetransfer abutment was secured. The im-pression was then taken to construct thefinal restoration. Finally, the fabricated

ceramo-metallic crown was permanentlycemented over the final abutment.

Results

This study included a total of 10 patients(six males and four females) with an av-erage age of 31 years (range 20–43 years).All patients selected had severely defec-tive extraction sockets in the mandibularpremolar–molar region (three premolarsand nine molars) (Table 1).

Clinical findings

A total of 13 rings were harvested. Fiverings were passively pulled out of the chinsimultaneously with trephine bur with-drawal. Six rings were removed with theaid of the anchored taping drill; two ofthem were found to be attached to thegenial muscles and were dissected usinga sharp periosteal elevator. One ringshowed cleavage at the junction of theouter cortical bone leaving the remainingpart of the ring in place during trephine burwithdrawal, which made it necessary toharvest another ring from the contralateral

540 Omara et al.

Fig. 7. Snapshot of the MPR (multiplanar reformatting) screen showing the postoperative assessment of bone density. (A) Bone density at thering–implant interface for both the buccal and lingual aspects. (B) The red arrow indicates the bone density of the ring–implant interface and theyellow arrow indicates the bone density of the ring–alveolus interface for both the mesial and distal aspects. (C) Adjusted orientation axes in theaxial slice. (D) Three-dimensional reconstruction of the grafted bone ring. (For interpretation of the references to color in this figure legend, thereader is referred to the web version of this article.)

side based on the radiographic dataobtained from the CBCT.

Three rings were 7 mm in diameter witha 3.5-mm central osteotomy and nine ringswere 9 mm in diameter with a 4-mm cen-tral osteotomy; the average length was6–10 mm. The harvested rings fitted per-fectly into the prepared defective sockets

Table 1. Demographic characteristics of the stu

Patientnumber Sex

Age(years)

1 Male 35 On2 Male 20 Tw

an3 Female 30 Tw4 Male 43 On5 Female 29 On6 Female 42 On7 Male 21 On8 Male 27 On9 Female 27 On

10 Male 29 On

without any need for re-contouring oradjustment, and the implants wereinstalled passively gaining their primarystability from the remaining apical bone ofthe sockets. No implant–ring complexshowed any degree of mobility at theend of implant installation. However,the ring in the first case was untapped

dy patients.

Number of sockets

e socket: lower right second molaro sockets: lower right second premolar

d second molaro sockets: lower left first and second molarse socket: lower right second premolare socket: lower right second premolare socket: lower left second molare socket: lower left first molare socket: lower left first molare socket: lower right first molare socket: lower right second molar

and subsequently cracked during the im-plant installation; this case was completedand the implant–ring complex healed suc-cessfully (Fig. 8).

Wound healing at both the donor andrecipient site was optimal in all patients,

Fig. 8. Clinical photograph taken using amirror, showing the only ring that crackedduring implant placement.

Ridge augmentation with bone ring transplant 541

Fig. 11. Graphs showing (A) the average bone height immediately postoperative and at 6months postoperative; (B) bone density at the ring–alveolus interface immediately postoperativeversus 6 months postoperative; (C) bone density at the ring–implant interface immediatelypostoperative versus 6 months postoperative.

Fig. 9. Clinical photographs showing (A) graft dehiscence immediately postoperative; (B)healing by secondary intention at 2 months postoperative.

Fig. 10. Clinical photographs showing the healing phase. (A) Complete coverage of thecovering screw by bone. (B) Appearance of the buried covering screw after removal of theexcess bony coverage.

without any signs of infection. Mild post-operative oedema was noted in all patients,which had resolved completely by therecall visit at 1 week postoperative. Twocases suffered from transient numbness ofthe lower lip, which disappeared by thefourth week postoperative. The crackedring showed graft dehiscence on the secondday postoperatively, which healed sponta-neously by secondary intention aftersmoothing of the lingual sharp edge andusing chlorhexidine mouth wash (Fig. 9).

The implants were surgically exposedfor superstructure construction 6 monthspostoperatively. The 12 implants showeda normal healing appearance, with com-plete coverage of the healing screw bybone for three implants. The other casesshowed varying degrees of minimal boneresorption (Fig. 10).

Radiographic findings

Immediately postoperative, the bone ringoutline could be seen, augmenting thesockets in three dimensions and creatingnew buccal walls where these had beenseverely defective after extraction. Radio-graphic images of the bone rings obtainedat 6 months postoperative showed that theradiopacity of their outer and inner corti-ces and the intermediate spongiosa wereindistinguishable from the surroundingbony trabeculae, with a homogeneous ap-pearance for seven rings. Two rings showeda decreased radiopacity of the outer andinner cortices and increased radiopacity ofthe intermediate spongiosa. Three ringsshowed no radiographic changes.

The difference in bone ring height mea-sured immediately postoperative and at 6months postoperative was not statisticallysignificant, with a mean crestal boneresorption of 0.2604 mm (P = 0.321)(Fig. 11A) (Table 2). The bone densityat the ring–alveolus interface showed astatistically significant increase for boththe mesial and distal aspect (mean bonedensity change of 420.43 HU mesially and325.28 HU distally) (Fig. 11B) (Table 3).Bone density at the ring–implant interfaceshowed a statistically significant increasefor both the mesial and buccal aspect (meanbone density change 393.21 HU mesiallyand 429.69 HU buccally), while the changewas not statistically significant for thedistal and lingual aspects (mean bone den-sity change 282.60 HU distally and263.86 HU lingually) (Fig. 11C) (Table 4).

Discussion

The quantity and quality of bone necessaryfor successful implant placement is

542 Omara et al.

Table 2. Bone height and crestal bone resorption (millimetres).

Minimum Maximum Mean SD P-value

Immediately postoperative 11.84 15.15 13.3363 1.23058 0.3216 months postoperative 10.69 14.86 13.0758 1.37821Amount of bone resorption �1.93 0.94 �0.2604 0.86855 0.321Percentage of bone resorption �12.73 6.77 �1.8932 6.40528 0.328

SD, standard deviation.

limited in defective sockets. The Salamaclassification of extraction site defectsemphasizes the effect of the degree ofthe buccal wall defect and its relationshipto implant placement and adjunctive aug-mentation techniques.1 Socket preserva-tion and guided bone regeneration haveproved to be successful only in the man-agement of Salama class I and class IIdefects with delayed or immediate implantplacement.7 Moreover, the process ofosseointegration might be hindered bythe alloplastic materials used in thesetechniques.25,26 However, in Salama classIII and IV defects, the sockets are severelycompromised with partial or total loss ofthe buccal plate of bone, and implantplacement within the remaining bonewould result in a significantly off-axisimplant position. Several techniquesaimed at solving this problem have been

Table 4. Bone density at the ring–implant inter

Mesial aspect Immediately postoperati6 months postoperative

Amount of density chanPercentage of density ch

Distal aspect Immediately postoperati6 months postoperative

Amount of density chanPercentage of density ch

Buccal aspect Immediately postoperati6 months postoperative

Amount of density chanPercentage of density ch

Lingual aspect Immediately postoperati6 months postoperative

Amount of density chanPercentage of density ch

SD, standard deviation.

Table 3. Bone density at the ring–alveolus inte

Mesial aspect Immediately postoperativ6 months postoperative

Amount of density changPercentage of density ch

Distal aspect Immediately postoperativ6 months postoperative

Amount of density changPercentage of density ch

SD, standard deviation.

reported. Titanium mesh augmentationtechniques have proved to be unpredict-able due to vulnerability to wound dehis-cence with subsequent resorption andsubstantial pseudo-periosteum formationbeneath the mesh.27 Concerning onlaybone graft techniques, the bone graft iscut without any sculpturing to fit the bonydefect, with subsequent delays in grafthealing and the stimulation of graft resorp-tion due to the lack of close proximity tothe graft bed. Moreover, in all onlay graft-ing techniques, a secondary surgical inter-vention is required for delayed implantplacement after graft consolidation.3

The pioneer work reported by Stevenset al.20 and Giesenhagen and Yuksel21 in2010, in two case reports of defectiveanterior sockets augmented with simulta-neous implant placement using chin bonerings, prompted this study to evaluate chin

face (Hounsfield units).

Minimum Maximum

ve �452.50 1001.00

70.70 1001.00

ge �160.20 1089.20

ange �41.70 1376.23

ve �199.50 853.00

51.10 1819.30

ge �389.80 1112.70

ange �20.18 514.39

ve 568.60 1220.80

248.80 2439.90

ge �834.40 1309.60

ange �77.03 173.67

ve 566.10 1941.80

656.80 1947.20

ge �555.20 1381.10

ange �28.59 243.97

rface (Hounsfield units).

Minimum Maximum

e �152.50 752.80

210.60 1406.10

e �236.30 1292.00

ange �773.90 2978.45

e �533.60 725.30

43.10 799.80

e 31.00 798.80

ange 10.27 4491.72

bone rings clinically and radiographicallyas a technique for the three-dimensionalaugmentation of severely defective sock-ets in the mandibular premolar–molarregion with simultaneous implant place-ment in a one-stage procedure.20,21

The chin bone graft is derived fromintramembranous bone, which shows lessresorption than grafts derived from endo-chondral bone. Moreover, the chin areacontains more cancellous bone than otherintraoral sites, thus providing a greateramount of osteoprogenitor cells.28–30 Fur-thermore, membranous bone grafts do notpresent a physical barrier to rapidly in-growing local vessels, and revasculariza-tion proceeds faster than in endochondralcortical bone with a thicker cancellouscomponent.31 Another important factoris that the harvesting of a bone ring fromthe chin region is more convenient thanfrom other intraoral donor sites, and suchrings can be utilized universally forintraoral augmentation of up to 6 mm ormore in three dimensions.18

In the current study, chin bone exposureusing a conservative unilateral vestibularapproach and layered flap closure, fol-lowed by immediate postoperative pres-sure band application, ensured proper

Mean SD P-value

224.72 470.29 0.008617.94 329.74393.21 421.52 0.008274.33 353.54 0.003

339.14 357.927 0.056621.74 517.730282.60 457.48 0.056100.62 121.09 0.001

848.79 208.93 0.0241278.48 530.61429.69 571.12 0.024

51.52 64.70 0.002

997.44 410.13 0.0981261.30 410.97263.86 505.57 0.098

25.60 62.27 0.082

Mean SD P-value

171.17 276.88 0.002591.60 364.00420.43 360.66 0.002375.04 979.88 0.103

38.90 298.43 0.002364.19 271.24325.28 272.45 0.002950.27 1565.61 0.014

Ridge augmentation with bone ring transplant 543

mentalis muscle reattachment, normalchin appearance, and minimal postopera-tive oedema in all cases.16,17 Regardinggraft harvesting, appropriate preoperativeradiographic planning of the chin area as adonor site allowed the precise determina-tion of the area from which the graft couldbe harvested to coincide with the socketdimensions (width, depth, and height) andwithout harming the adjacent vital struc-tures. An end-cutting trephine bur designwas used and the trephination protocol thatwas followed prevented heat damage tothe bone and allowed safe graft harvesting.During the outlining of the chin ring it isextremely important to adjust the longitu-dinal axis of the trephine bur to be per-pendicular to the outer cortex of the chin inorder to obtain an absolutely cylindricalbone ring. Another important factor is toensure that the centralization of the im-plant osteotomy in the ring is parallel tothe longitudinal axis of the ring. Both ofthese factors, together with proper angu-lation of the trephine bur during prepara-tion of the premolar/molar socket walls,ensures proper implant placement in rela-tion to the opposing dentition.

Graft/bed proximity was achieved inthis technique through preparation ofthe defective sockets using a trephinebur sequentially smaller than the bur thatwas used to harvest the bone ring, thusallowing the bone ring to be fitted snuglyin its recipient site with adequate stabilityand maximum surfaces of bony contact.This was directly reflected in the earlygraft healing with subsequent decreasein graft resorption and is in accordancewith the findings of Marx, who empha-sized the importance of graft stabilityduring the early phases of bone healingand the reflection of this on early vascu-larization and graft incorporation.32

All bone rings were placed in the de-fective sockets and the implants screwedin without cracking, with the exception ofone ring. This one ring cracked because itscentral osteotomy was prepared withouttapping. The tapping drills of the selectedimplant system were utilized only to pro-vide a central implant osteotomy site ofminimal difference to the implant diameter,which facilitated passive implant place-ment without cracking and without rota-tional or torque forces on the bone ring.Meanwhile, the apical basal bone of thesocket was only prepared with a final clas-sical drill in order to obtain adequate pri-mary stability of the implant–ring complex.

All cases showed optimum soft tissuehealing at the grafted socket without anysigns of infection or wound dehiscence,except in the case of the cracked ring

where dehiscence occurred on the lingualside. This was most likely due to the sharpedge of the ring and the thin lingual mu-cosal coverage, which was prevented inthe subsequent cases through smoothingof the ring margin.

The statistical increase in bone densityat the ring–alveolus and ring–implantinterfaces and the minimal crestal boneresorption in the linear measurement dur-ing the follow-up period reflected the goodincorporation of the intramembranouschin bone ring due to rapid angiogen-esis,9,10 with subsequent consolidation ofthe bone ring into the adjacent alveolarbone and integration of the installed im-plant into the healed ring. The radiograph-ic changes in bone trabeculation werefurther evidence of the progression ofhealing of the bone ring in the socketbed and subsequently served as a positiveparameter for implant integration, andthese changes were correlated to the clini-cal findings.

The findings of the current studyshowed the autogenous chin bone ringaugmentation technique to be a reliableand technically applicable alternativemethod for the three-dimensional augmen-tation of severely defective sockets withsimultaneous implant placement in a one-stage procedure. Furthermore, this tech-nique reduced the treatment period to only6 months, from the beginning of surgery tothe patient receiving the final restoration. Along-term study is proposed to evaluate theimplant durability after loading.

Funding

This study was self-funded. There are nofinancial relationships between the authorsand any manufacturer/supplier of anycommercial products or services relatedto this work.

Competing interests

The authors declare that they have nosignificant competing financial, profes-sional, or personal interests that mighthave influenced the performance or pre-sentation of the work described in thismanuscript.

Ethical approval

All patients were selected from the outpa-tient clinic of the Department of Oral andMaxillofacial Surgery, Faculty of Oral andDental Medicine, Cairo University. Thepresent study was approved by the EthicsCommittee of the Faculty of Oral andDental Medicine, Cairo University.

Patient consent

Written consent was obtained from allpatients for the use of their clinical photo-graphs as a scientific demonstration inthis paper.

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Address:Mohammed Abdelsalam Ibrahim MahdyOmaraVilla Abdelsalame OmaraEl MansouryaKirdasaGizaEgyptTel: +20 01286004984E-mail: omara_mohammed@ymail.com