histologic analysis of healing after tooth extraction with ridge

Histologic Analysis of Healing AfterTooth Extraction With RidgePreservation Using MineralizedHuman Bone AllograftTina M. Beck* and Brian L. Mealey*

Background: Ridge preservation was developed as a ther-apy to prevent severe bone resorption after tooth extraction.The purpose of this study is to determine if there is any differ-ence in the amount of new bone formation �3 months afterextraction and ridge preservation compared to that after �6months.

Methods: Minimally traumatic extraction with ridge preser-vation using mineralized human bone allograft was performedat 38 single-rooted tooth sites in 33 subjects. Sixteen siteshealed for an average of 14 weeks (early healing), whereas22 sites were allowed to heal for an average of 27 weeks(delayed healing) before harvesting bone core samples. Histo-morphometric analysis was performed to determine the per-cent of new bone formation, residual graft particles, andconnective tissue/non-mineralized structures for each site.

Results: All specimens showed evidence of new bone for-mation, with most of the residual graft particles surrounded in-timately by woven bone. No statistically significant differencesin the amount of newly formed bone or residual graft particleswere found between the two groups. Overall, the early healinggroup demonstrated a mean of45.8% new bone, 14.6% residualgraft material, and 39.6% connective tissue/non-mineralizedtissue. The delayed healing group showed mean values of45%, 13.5%, and 41.3%, respectively.

Conclusion: The results of this study suggest that waiting�6 months after tooth extraction and ridge preservation usingmineralized bone allograft does not provide a greater amountof new bone formation or less residual bone particles comparedto that after only�3 months. J Periodontol 2010;81:1765-1772.

KEY WORDS

Bone transplantation; dental implants; tooth extraction.

Dental implants have been widelyaccepted as a predictable treat-ment option for the replacement

of missing teeth.1-4 In recent years, treat-ment protocols have shifted from place-ment of implants only into mature lamellarbone5 to procedures that reduce overalltreatment times, such as the immediateplacement of dental implants into freshextraction sites. A clinical study of bonehealing after tooth extraction revealedthat the average single-tooth extractionsite loses 50% of its alveolar width, anaverage loss of 6.1 mm, during the 12months after extraction.6 Araujo et al.7

reported an average loss of 2.5 mm, orabout 35%, of ridge width in the 6 monthsafter tooth extraction in a dog model.Significantly greater resorption of thefacial aspect of the ridge was seen afterextraction compared to the lingual as-pect. In a study evaluating the morpho-logic changes of the alveolar ridge afterextraction of maxillary anterior teeth inhumans, Nevins et al.8 found an averageloss of 5.2 mm in buccal ridge height inteeth with prominent roots and intact,but thin, buccal plates. Some cases lostas much as 9 mm in buccal ridge heightafter extraction. Clearly, the changes inalveolar dimension after tooth extrac-tion may greatly alter treatment de-cisions including the ability to place adental implant for optimal esthetics andlong-term success.

* Department of Periodontics, University of Texas Health Science Center San Antonio,San Antonio, TX.

doi: 10.1902/jop.2010.100286

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Ridge preservation was developed as a techniqueto preserve alveolar dimensions during the healingof an extraction site when immediate implant place-ment is contraindicated. In general, most studies showa smaller loss of ridge width when sockets are graftedcompared to when they are not grafted.8-10 Severalmaterials have been studied for this purpose andproven successful to varying degrees, including au-togenous bone, allografts, xenografts, and alloplasticmaterials;8-10 however, the ideal healing time beforeimplant placement is unclear. Studies on ridge preser-vation have generally provided healing times of 2 to12 months before implant placement.9 To date, nocontrolled clinical trials in humans have examineddifferences in new bone formation within the formertooth socket at varying time intervals after ridge pres-ervation grafting. Therefore, the purpose of this studyis to determine if there is any difference in the amountof new bone formation 3 months after tooth extrac-tion and ridge preservation compared to that after6 months using the same allograft material in bothgroups of subjects.

MATERIALS AND METHODS

Patient SelectionThe Institutional Review Board of the University ofTexas Health Science Center at San Antonio re-viewed and approved this research protocol, and thisstudy was conducted in accordance with the HelsinkiDeclaration of 1975, as revised in 2000.11 A poweranalysis was performed to determine the numberof subjects needed to detect a clinically significantmean difference of one standard deviation or more,assuming a minimum of 70% of the subjects to be fullycompliant, using a Mann-Whitney U test at the 0.05level with a power of 88.5%. It was determined thata minimum of 14 histologic samples were requiredper treatment group. To allow for an anticipatedrate of 30% dropouts, a total of 20 subjects wereenrolled per group, for a total of 40.

Subjects were recruited from the University ofTexas Health Science Center at San Antonio dentalpatient pool between January 2008 and April 2009.All potential subjects were screened and written con-sent obtained if the eligibility criteria were met. El-igible subjects had ‡1 single-rooted tooth with aminimum of 10 mm bony support that required ex-traction and replacement with a dental implant. Care-ful attention was paid to select only sites where thetooth location and root angulation was consistentwith the ideal future implant orientation and whererestorative space was adequate for a dental implant.Presence of any acute infection or the presence ofa periapical lesion were exclusion criteria. Subjectswere not enrolled if they were pregnant or planningto become pregnant during the study period; if there

was any medical contraindication to dental surgery;or if they had a medical condition or therapeutic regi-men known to affect hard or soft tissue healing, such asautoimmune disease, immunosuppressive therapy, orpoorly controlled diabetes (HbA1c >7%). Forty subjectsbetween the ages of 18 and 99 were sequentially allo-cated to one of two treatment groups. The first 20 sub-jects enrolled were assigned to the delayed healinggroup and the remaining 20 subjects were assignedto the early healing group. Multiple single-rooted teethfrom the same subject were included if they met theinclusion criteria, and all sites within a subject were inthe same healing group, early or delayed.

Surgical ProtocolNo presurgical antibiotics were provided and allsubjects received a single dose of 800 mg ibuprofenbefore extraction. After administration of local an-esthesia, minimally traumatic extraction was per-formed. The sockets were thoroughly degranulatedand examined for the presence of a fenestration or de-hiscence. The following measurements were recordedusing a periodontal probe† and rounded to the nearestmillimeter: the depth of socket on facial and lingual/palatal measured from the most apical aspect of thesocket to the most apical point on the correspondingalveolar crest; and the height of the buccal and lingualcortices measured at the mesio-distal midpoint of theadjacent teeth using a horizontal reference line markedwith a periodontal probe connecting the midfacialcemento-enamel junction of the adjacent teeth. Nostent was used during the dimensional measurements.In addition, sharp calipers‡ were used to measurethe bucco-lingual ridge width at the mesio-distal mid-point between adjacent teeth at a level 2 mm apicalfrom the ridge crest; and the buccal plate thickness2 mm apical from the ridge crest at the mesio-distalmidpoint of the socket. Because flaps were not re-flected, the points of the caliper were generally piercedthrough the soft tissue until they contacted the bone.

After copious irrigation, hydrated particles of 250 to1,000 mm non–freeze-dried cancellous mineralizedhuman bone allograft§ were lightly compressed intothe socket.The socket was filled to the crest of the ridgeand a double layer of bioabsorbable collagen wounddressingi was placed on top of the graft and securedwith sutures in a cross-mattress technique (Fig. 1).If a bony dehiscence or fenestration was evident, asocket repair procedurewas performed by placing a bi-oabsorbable collagen membrane¶ inside the socketbefore grafting. Flap elevation was not performed atany site. If >50% of any socket wall was absent, the site

† UNC-15 periodontal probe, G. Hartzell & Son, Concord, CA.‡ Castroviejo caliper, Salvin Dental Specialties, Charlotte, NC.§ Puros, Zimmer Dental, Warsaw, IN.i Colla Tape, Zimmer Dental.¶ Socket Repair Membrane, Zimmer Dental.

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was excluded from further studyand lateral ridge augmentationwas performed.

Customary postoperative in-structions were provided andall patients were prescribed100 mg doxycycline twice dailyfor 10 days and 0.12% chlor-hexidine mouthrinse twice dailyuntil the sockets were 100% epi-thelialized(range,10to21days).Narcotic analgesics were pre-scribed for some, but not all sub-jects, depending on the patientdesires and anticipated pain lev-els. Sutures were removed after2weeks.Subjectswhopresentedwith signs and symptoms con-sistent with infection were pre-scribed 500 mg amoxicillinthree times daily for 1 week.

Follow-UpSubjects from the early healinggroup were recalled 2 monthsafter extraction for a cone-beam computerized tomogra-phic (CBCT) scan to evaluatethe site for implant placement.Subjects from the delayed heal-ing group were recalled for theCBCT 5 months after extrac-tion. Once the CBCT had beenobtained for each subject, theimplant surgery was scheduledwithin 3 to 6 weeks. At the timeof implant placement, the buc-cal and lingual ridge height andthe ridge width were measuredafter flap reflection using theaforementioned techniques. Ahollow trephine drill with 2-mminternal diameter was used toobtain hard tissue biopsies8 mm in length from all implantrecipient sites. The apical as-pect of all biopsies was markedto identify the apico-coronal ori-entation during histologic anal-ysis and then placed into 10%neutral buffered formalin.

Histologic Processing andAnalysisBiopsies were decalcified, dehy-drated, embedded in paraffin,and sectioned apico-coronally

Figure 1.Composite of clinical photographs from a subject in the early healing group. A) Initial presentation ofhopeless #10. B) Occlusal view #10. C) Minimally traumatic extraction with allograft and bioabsorbablemembrane in place. D)Occlusal view of C. E) Clinical healing after 3 months. F) Occlusal view of E. G) Finalrestoration #10.

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into multiple 4-mm thick sections. Sections werestained with Harris hemotoxylin and counterstainedwith treosin using routine procedures. The innermosttwo sections of each biopsy were examined at a min-imum of ·20 magnification. Digital images of eachsection were acquired and imported into a softwareimaging program# to create individual layers of newvital bone, residual graft particles, and connectivetissue/non-mineralized tissue (CT). These layerswere then imported into image analysis software**to determine the percent composition of vital bone,residual graft particles, and CT.

Statistical AnalysisStudent t tests and Mann-Whitney U tests were used tocompare the area of newly formed vital bone, residualgraft particles, and CT for sites with <4 months of heal-ing (early healing) to those with >5 months healing(delayed healing). For the few subjects who had twosites included for analysis, the differences in new boneformation between the two sites within the same sub-ject ranged from 14% to 36%, a difference that wassimilar to differences between sites from different sub-jects. Biopsies were further analyzed for the effect ofperforming a socket repair procedure using Mann-Whitney U tests. Spearman correlations were usedto evaluate and relationship between clinical findingsand histologic parameters. Findings were consideredsignificant when P <0.05.

RESULTS

Clinical FindingsThirty-three of the 40 enrolled subjects completed thestudy. One subject was exited because of the pres-ence of a dehiscence >50% of the buccal plate andsix subjects were not compliant with the study proto-col. Thirteen males and 20 females with an averageage of 57.4 years (range, 39 to 76) completed thestudy, with no statistically significant differences be-tween groups. Reasons for extraction included non-restorable teeth caused by fracture or decay and failedendodontic rescues. Teeth with apical lesions wereexcluded.

Thirty-eight sites in 33 subjects were analyzed, withfive subjects contributing two sites each. When twosites were present in a single subject, both sites werein the same healing group. In the subjects with 2 sitesincluded for analysis, sites were considered to be sta-tistically independent because analysis determinedthat the range of percent new bone formation betweensites within a single subject were similar to the range ofpercent new bone formation between sites from differ-ent subjects. The 22 sites in the delayed healing grouphad an average healing time of 27 weeks (–14 days),whereas the 16 sites in the early healing group had anaverage healing time of 14 weeks (– 11 days). Sites

were evenly distributed between the two studygroups, with 24 sites in the maxilla and 14 sites inthe mandible.

One site in the early healing group and two sites inthe delayed healing group presented with signs ofpotential infection at the 7- to 10-day postoperativefollow-up. After administration of 500 mg amoxicillinthree times daily for 7 days, all sites healed with-out further complications. Four sites from the de-layed healing group presented with deficient fill ofthe socket at the 7- to 10-day follow-up and were sus-pected to have lost some or all of the graft material.Two of these sites were in the same subject. None ofthe sites in the early healing group presented withsigns of lost graft material during healing.

After osteotomy preparation, 34 of the 38 studysites achieved primary implant stability, with the re-maining four sites exhibiting insufficient ridge width toprovide primary stability. These sites received guidedbone regeneration and the implants were placed suc-cessfully 6 months later.

Histologic ObservationsLight microscopic evaluation showed that 37 out ofthe 38 histologic specimens had well-defined orga-nized lamellar structures with lacunae absent of os-teocytic nuclei, a presentation consistent with residualallograft particles. One specimen demonstrated noresidual allograft particles. Most of the lamellar struc-tures were observed intimately surrounded by a hap-hazard arrangement of collagen-rich, anastomosingmineralized tissue generally lacking organized lamel-lar structure and canaliculi, an observation consistentwith newly formed woven bone. Resorption bays withmultinucleated giant cells were identified in somespecimens. Scattered osteocytes and blood vesselswere consistently observed throughout the wovenbone. Specimens presented with variable amountsof loose, fibrous stroma filled with plump, spindle-shaped mesenchymal cells, fibroblasts, adipocytes,and few inflammatory cells. Numerous vascular struc-tures were observed interspersed in this connectivetissue matrix (Fig. 2).

Histomorphometric AnalysisThe early healing group had a similar percentage ofnew vital bone formation, residual graft material,and non-bone CT compared to the late healing group(Table 1). There were no statistically significant differ-ences between groups for any of the histologic param-eters. When the four sites that were associated withpartial or complete loss of the graft during healingwere excluded, the delayed healing group had an av-erage of 41.8% (– 19.3%) vital bone; 43.1% (– 12.3%)

# Adobe Photoshop Elements 7, Adobe Systems, San Jose, CA.** Image J, National Institutes of Health, Bethesda, MD.


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CT bone; and 15.3% (– 12%)residual graft material. No sta-tistically significant differencebetween groups for any histo-logic parameter was identifiedwhen the seven sites that ex-perienced either postopera-tive loss of graft material orsigns of potential infectionwere excluded from analysis.In addition, no statistically sig-nificant differences were ob-served when comparing thecomposition of the biopsy(amount of vital bone, CT,and residual graft material)with maxillary versus mandibu-lar sites, smokers versus non-smokers, and subjects withcontrolled type 2 diabetes mel-litus versus healthy subjects.

Overall, the percentage ofvital bone was negatively corre-lated with the percentage of CT(r = -0.827) and the percentageof residual graft material (r =-0.763). The percentage of re-sidual graft material was notcorrelated with the percentageof CT. The four sites requiringsocket repair membranes hadsignificantly higher mean per-centage of CT (56.3% – 6.6%; P = 0.024) and signifi-cantly lower mean percentage of vital bone (19.3% –8.8%; P = 0.01) and residual graft material (26.8% –1%; P = 0.035) compared to all other sites. The foursites that presented with deficient socket fill at the7- to 10-day follow-up had significantly lower meanpercentage of residual graft material (P = 0.003) com-pared to the 30 sites that healed without complica-tions.

Dimensional ChangesFrom a mean initial ridge width of 8.47 mm, the earlyhealing group had an average loss of 1.47 mm inridge width (17.3%), whereas the delayed healinggroup initially had a mean width of 9.38 mm and lostan average of 1.43 mm (15.2%) (Table 2). The earlyhealing group lost <1 mm of buccal and lingual ridgeheight, whereas the delayed healing group lost <1mm of lingual ridge height and showed a slight aver-age gain in buccal ridge height. No statistically signif-icant or clinically relevant differences in averagedimensional changes between the two healing groupswere found, nor was there a correlation with biopsycomposition. No correlation was found between

Figure 2.Composite of one clinical photograph and four histologic slides all stained with hemotoxylin and treosin.A) Clinical photograph of core biopsy; ink stains the apical end of the core. B) Magnification ·1 of corebiopsy in A. C) Magnification ·4 of rectangle in B showing new bone formation (NB) in intimate contactwith residual graft particles (RG). D) Magnification ·10 showing empty lacunae in RG and osteocytesin NB. E) Magnification ·40 showing empty lacuna in RG and osteocytes in NB.

Table 1.

Histomorphometric Analysis

Vital New

Bone

(% – SD)

Residual Graft

Material

(% – SD)

CT

(% – SD)

Early healing 45.8 – 22.4 14.6 – 12.9 39.6 – 13.0

Delayed healing 45.0 – 19.8 13.5 – 12.2 41.3 – 14.6

No significant differences between groups for any parameter (P >0.05).

Table 2.

Changes in Ridge Dimensions

Loss of

Ridge

Width

(mm – SD)

Loss of

Buccal Ridge

Height

(mm – SD)

Loss of

Lingual Ridge

Height

(mm – SD)

Early healing 1.47 – 1.81 0.37 – 1.46 0.87 – 1.46

Delayed healing 1.43 – 1.89 -0.32 – 2.61* 0.61 – 1.38

* Negative number indicates gain in buccal ridge height.


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buccal plate thickness and changes in ridge height orwidth. Furthermore, buccal plate thickness and initialridge width were not correlated with biopsy composi-tion, regardless of healing time.

DISCUSSION

The primary aim of this study is to histologically eval-uate new bone formation using a single bone allograftmaterial at two different time points after tooth extrac-tion and socket grafting. All sites examined in thisstudy displayed evidence of new bone formation.No statistically significant difference in the amountof new bone formation was found between sites thathealed for an average of 14 weeks compared to thosethat healed for an average of 27 weeks (45.8% and45%, respectively). These findings are consistent withstudies evaluating new bone formation 9 to 10months after sinus augmentation using mineralizedhuman bone allograft12,13 and when used for thepurpose of ridge preservation.12 Our results demon-strating approximately 45% to 46% new vital bone for-mation, 14% to 15% residual graft particles, and 40%to 41% non-bone CT compare favorably with those ofFotek et al.13 who reported a range of 27% to 32% vitalnew bone formation 16 weeks after ridge preservationin 18 sites, with an average of 14% to 15% residualbone graft particles and 53% to 58% non-bone CT.In a case series of seven sites examined 16 to 20weeks after ridge preservation with mineralized hu-man bone allograft using a similar procedure to thatreported in the current study, Wang et al.14 reportedan average of 68% vital bone, 4% residual bone graft,and 38% non-bone CT. In an undisturbed socket,Trombelli et al.15 reported an average of only32.36% woven bone formation 6 months after toothextraction. Together, these studies suggest that ridgepreservation techniques using mineralized humanbone allograft may promote new bone formation inthe healing extraction socket.

A wide variability of new bone growth, residual graftmaterial, and connective tissue has been reportedusing various graft materials and ridge-preservationtechniques.9 This variability may be affected by mul-tiple factors, such as the disease status of the toothbefore extraction, inclusion of both single and multi-rooted teeth within a single study, size of the ex-traction socket, presence of bony dehiscences orfenestrations, trauma from extraction, damage tothe periodontium before extraction, or angulation ofthe biopsy core relative to the angulation of the for-mer tooth and the resulting healing extraction site.In this study, only single-rooted teeth were included,all teeth were extracted with minimal trauma, siteswere thoroughly examined for the presence of bonydehiscences or fenestrations, no teeth were includedthat had evidence of severe periodontitis, all roots

were required to have a minimum of 10 mm radio-graphic bone support, and all roots had to have anangulation similar to the angulation of the implantto be placed at the site. This ensured adequate depthof socket and angulation of the core trephine to allowbiopsies to contain only newly formed bone, as op-posed to mature alveolar bone present at the rootapex or along the socket wall. In addition, only the in-nermost aspect of the core biopsies was analyzed,presenting the area farthest from the socket wall.Only one biopsy specimen was observed withoutany residual graft particles but it also lacked maturelamellar bone indicating that the biopsy was indeedharvested from the previous extraction site that hadhealed with newly formed woven bone.

Most of the newly formed bone in the current studywas woven bone, and the relative lack of newly formedlamellar bone was an interesting finding. We ex-pected minimal lamellar bone in the early healinggroup, but not in the late healing group where we an-ticipated a higher degree of lamellar bone formation.In other studies a combination of woven and lamellarbone was often found at 5 to 6 months postgrafting.14

Iasella et al.10 reported an average of 54% vital newbone formation 6 months after extraction and socketgrafting with mineralized freeze-dried bone, and mostof the new bone was woven bone, with less lamellarbone formation. The histologic sections analyzed inour study were taken from the innermost aspect ofthe core biopsies, the location likely to take the lon-gest to turn over woven bone to lamellar bone.

Several reports on the success of ridge preserva-tion involve elevation of a mucoperiosteal flap forplacement of a collagen membrane16,17 and primarycoverage of the extraction site.8 Although these tech-niques have proven successful in preventing exces-sive loss of alveolar dimensions, they may increasepostoperative discomfort for the patient and the addi-tion of a membrane often significantly increases theoverall cost of the procedure. In addition, elevationof a mucoperiosteal flap can increase the risk of reces-sion on adjacent teeth if an envelope technique isused, scar formation may occur if vertical incisionsare made, and loss of keratinized tissue width with re-duction of vestibular depth may occur because of thecoronal advancement of the mucogingival junction.

The current study avoided mucoperiosteal flap el-evation and used sharp-tipped calipers to make ridgemeasurements. The dimensional measurementsfound an average loss of only 0.35-mm buccal ridgeheight and 1.46-mm loss of ridge width. These resultsare clearly an improvement from the 1.67-mm aver-age loss of mid-buccal height and 3.87-mm loss ofridge width recently reported in a systematic review18

that evaluated the changes in ridge dimensions aftertooth extraction without any attempts at ridge


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preservation. The findings of the current study aresimilar to that reported by Crespi et al.19 using mag-nesium-enriched hydroxyapatite, which observed anaverage loss of 0.48 mm in ridge height after 3months. Fotek et al.13 observed an average loss of1.11 mm in ridge height using mineralized humanbone allograft with an acellular dermal matrix and0.25 mm using mineralized human bone allograftwith a polytetrafluoroethylene membrane. These find-ings are further supported by a systematic review thatconcluded that minimally traumatic extraction withridge preservation can predictably preserve preex-traction alveolar dimensions.9 Evaluation of changesin ridge dimension was a secondary aim of the currentstudy, and no stents were used as fixed referencepoints during dimensional measurements. Thus, wecannot state with certainty that pregrafting and post-grafting measurements were made at exactly thesame vertical point on the ridge in each case. Thismay explain how a few cases showed an increase inridge width, a result that would not normally be ex-pected when a bone graft is contained within a socket.

Four of the 38 study sites failed to achieve primaryimplant stability because of insufficient ridge width.One of these sites lost only 1 mm in ridge width; how-ever, the initial ridge width was only 5 mm. Two of thesites were areas that presented with lost graft materialwithin 2 weeks of extraction and ridge preservationand displayed >2 mm loss in ridge width. The final sitethat failed to achieve primary implant stability pre-sented with a bony dehiscence of the buccal plate atthe time of extraction; this site had received a socketrepair membrane at the time of ridge preservationbecause of some deficiency of facial ridge height. Al-though the buccal ridge height increased by 4 mm atthis site after healing, the final ridge width was only3.5 mm. These findings suggest that a site presentingwith narrow initial ridge width, deep bony dehiscenceof the buccal socket wall, or exhibiting loss of graftmaterial within 2 weeks of extraction, may require ad-ditional augmentation techniques.

CONCLUSIONS

The present study indicates that there are no statisti-cally significant differences in the amount of new bonegrowth or residual graft particles �6 months after ex-traction and ridge preservation using mineralized hu-man bone allograft compared to that after only �3months of healing. Therefore, waiting an extended pe-riod of time after extraction and ridge preservationuntil implant placement to allow more time for boneformation and graft resorption was not supported bythis study. These results may not apply to grafting withother allograft, xenograft, or alloplast materials. Basedon the observation of similar amounts of new bonegrowth, it may be speculated that implants placed 3

months after extraction and ridge preservation withmineralized human bone allograft will have similar suc-cess rates to those placed after longer healing periods;however, further studies are recommended to validatethis assumption.

ACKNOWLEDGMENTS

The authors thank Sonja A. Bustamante at the Uni-versity of Texas Health Science Center San Antonio(UTHSCSA) for her help with histologic preparation.They also thank Mr. John D. Schoolfield (UTHSCSA)for his invaluable help with statistical analyses. The cur-rent study received no financial support. Dr. Mealeyhas received research funding and lecture honorariafrom Zimmer Dental. All other authors report no con-flicts of interest related to this study.

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13. Fotek PD, Neiva RF, Wang HL. Comparison of dermalmatrix and polytetrafluoroethylene membrane for socketbone augmentation: A clinical and histologic study.J Periodontol 2009;80:776-785.

14. Wang HL, Tsao YP. Histologic evaluation of socketaugmentation with mineralized human allograft. Int JPeriodontics Restorative Dent 2008;28(3):231-237.

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19. Crespi R, Cappare P, Gherlone E. Magnesium-enrichedhydroxyapatite compared to calcium sulfate in thehealing of human extraction sockets: Radiographicand histomorphometric evaluation at 3 months. J Peri-odontol 2009;80:210-218.

Correspondence: Dr. Brian L. Mealey, UTHSCSA Depart-ment of Periodontics, MSC 7894, 7703 Floyd Curl Dr., SanAntonio, TX 78229–3900. Fax: 210/567-3761; e-mail:[email protected].

Submitted May 11, 2010; accepted for publication June23, 2010.


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histologic analysis of healing after tooth extraction with ridge

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