T he healing process in extraction

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1 BRANDAM ET AL IMPLANT DENTISTRY / VOLUME 24, NUMBER Ridge Preservation Techniques in the Anterior Esthetic Zone Luis Brandam, DDS,* Hans Malmstrom, DDS, Fawad Javed, BDS, PhD,* Jose-Luis Calvo-Guirado, DDS, MS, PhD, and Georgios E. Romanos, DDS, PhD, Dr. Med. Dent T he healing process in extraction ridges is characterized by internal changes that lead to bone formation within the ridge and external changes that result in loss of the alveolar ridge width and height. This loss of alveolar bone volume after tooth extraction often complicates prosthetic reconstruction after implant placement. To preserve the ridge contours, various techniques and grafting materials have been reported in the literature, with promising results. Several terms have been used to describe such attempts at conserving the integrity of the ridge walls after tooth extraction, including ridge preservation (RP) and site preservation. The authors consider the term ridge preservation to be the most precise and hence have used it in this review. Although many animal studies and clinical case series have demonstrated a role for alveolar ridge-preservation techniques, published reports have covered a wide gamut of techniques, including such variables as the extraction site location (anterior/posterior; *Resident, Division of General Dentistry, Eastman Institute for Oral Health, University of Rochester, Rochester, NY. Professor and Chair, Division of General Dentistry, Eastman Institute for Oral Health, University of Rochester, Rochester, NY. Professor, Department of International Dentistry Research, Faculty of Medicine and Dentistry, San Antonio Catholic University of Murcia (UCAM), Murcia, Spain. Professor, Department of Periodontology, School of Dental Medicine, Stony Brook University, Stony Brook, NY; Professor, Department of Oral Surgery and Implant Dentistry, University of Frankfurt, Dental School (Carolinum), Frankfurt, Germany. Reprint requests and correspondence to: Georgios E. Romanos, DDS, PhD, Dr. Med. Dent., School of Dental Medicine, Stony Brook University, 106 Rockland Hall, Stony Brook, NY , Phone: (631) , Fax: (631) , georgios.romanos@ stonybrook.edu ISSN /15/ Implant Dentistry Volume 24 Number 6 Wolters Kluwer Health, Inc. All rights reserved. DOI: /ID Purpose: Various techniques have been developed to limit resorption of the alveolar ridge after tooth extraction, and results from using them have been promising. The aim of this study was to evaluate the role and reliability of ridge preservation (RP) in the anterior esthetic zone, in anticipation of later implant placement. Materials and Methods: Using the MEDLINE and PubMed databases, searches were performed using combinations of different terms. Results: A total of 223 studies were identified, from which 55 articles were further examined. Of these, 11 studies were randomized clinical trials, controlled clinical trials, or prospective/retrospective studies with a minimum of 5 subjects maxillary/mandibular); whether a flap was elevated; whether grafting materials were used, and if so, what kind; whether a membrane was used; and whether primary closure of the ridge was obtained. The aim of this article was to focus on the anterior maxilla, asking whether using ridge-preservation techniques in the esthetic zone reliably preserves the alveolar ridge in preparation for dental implant placement? MATERIALS AND METHODS In MEDLINE and PubMed, searches were performed for articles in English language using the following terms and combination of them: dentistry, implants, dental implants, and at least 3 months of follow-up. Only human studies of RP for singlerooted tooth or bicuspid sites were included. Selection criteria also excluded studies in which primary closure was obtained. Conclusion: Although a direct comparison of the 11 articles was difficult because of the different techniques, materials, and healing time, no single graft material seemed to be superior. However, all studies found less ridge contraction at grafted than nongrafted sites. Longterm data about the outcomes for implants placed in sites where RP was attempted are still needed. (Implant Dent 2015;24: ) Key Words: anterior zone, bone graft, bone loss prevention, ridge preservation extraction, implants-ridge preservation, ridge preservation, ridge-ridge, ridge alteration-extraction, ridge preservation-extraction ridge, and ridge preservation. The search was limited to human subjects. Bibliographies of reviews from 1994 to March 2012 were assessed for appropriate studies. Reference lists of studies identified were searched for further citations. Of those that were initially identified, studies were considered for inclusion in the present review if they were randomized clinical trials (RCTs), controlled clinical trials, or prospective/ retrospective studies with a minimum of 5 patients and a follow-up of at least

2 700 RIDGE PRESERVATION TECHNIQUES BRANDAM ET AL Table 1. Excluded Articles and Reason for Exclusion Article Author Year Reason for Exclusion Osseoretention? Comparative assessment of particulate Hoad-Reddick 1994 Primary closure hydroxyapatite inserted beneath immediate dentures et al 1 A comparison of demineralized freeze-dried bone and autologous bone to induce bone formation in human extraction ridges Becker et al Primary closure and periodontal teeth Clinical and histological observations of sites implanted with intraoral autogenous bone grafts and allografts. Fifteen human Becker et al Unclear data and posterior teeth case reports Bone regeneration in extraction sites after immediate placement of Dies et al Primary closure an e-ptfe membrane with or without a biomaterial Alveolar ridge preservation following extraction of maxillary teeth. Report on 23 consecutive cases Nemcovsky and Serfaty Primary closure by rotated flap A bone regenerative approach to alveolar ridge maintenance Lekovic et al Primary closure following tooth extraction. Report of 10 cases Preservation of alveolar bone in extraction ridges using bioabsorbable membranes Lekovic et al Primary closure and periodontal teeth Alveolar ridge reconstruction and/or preservation using root form Yilmaz et al Primary closure bioglass cones Autogenous masticatory mucosal grafts in extraction ridge seal procedures: a comparison between ridges grafted with demineralized freeze-dried bone and deproteinized bovine bone mineral Histomorphometric evaluation of extraction ridges and deficient alveolar ridges treated with allograft and barrier membrane: a pilot study Histologic evaluation of human extraction ridges treated with DFDBA and cell occlusive membrane Preserving alveolar ridge anatomy following tooth removal in conjunction with immediate implant placement Changes in alveolar bone height and width following ridge augmentation using bone graft and membranes Porous bovine mineral in healing of human extraction ridges. Part 1: histomorphometric evaluations at 9 mo Evaluation of the effect of immediate grafting of mandibular postextraction ridges with synthetic bone Histological comparison of healing extraction ridges implanted with bioactive glass or demineralized-dried bone allograft: a pilot study Dental implant placed in extraction sites implanted with bioactive glass: Human histology and clinical outcome Use of HTR synthetic bone grafts in conjunction with immediate dental implants Changes in alveolar bone height and width following postextraction ridge augmentation using a fixed bioabsorbable membrane and demineralized freeze-dried bone osteoinductive graft Bone healing and soft tissue contour changes following singletooth extraction: a clinical and radiographic 12-mo prospective study The use of bovine porous bone mineral in combination with collagen membrane or autologous fibrinogen/fibronectin system for ridge preservation following tooth extraction Healing of human extraction ridges filled with Bio-Oss Tal Primary closure (soft tissue from palate) Smukler et al Primary closure Brugnami et al Primary closure Sclar Lack of data Simon et al Primary closure and augmented sites Artzi et al Primary closure Bolouri et al Primary closure Froum et al Primary closure Norton and Wilson Defected ridges and augmented sites Yukna et al Posterior teeth, primary closure and implants and graft at the same time Zubillaga et al Primary closure Schropp et al Posterior teeth Vasilic et al Primary closure Carmagnola 2003 Posterior teeth et al 22 (continued on next page)

3 BRANDAM ET AL IMPLANT DENTISTRY / VOLUME 24, NUMBER Table 1. (Continued) Article Author Year Reason for Exclusion Preservation of ridge dimensions following grafting with coral granules of 48 post-traumatic and post-extraction dentoalveolar defects Efficacy of bovine bone mineral for alveolar augmentation: a human histologic study Histologic evaluation of human biopsies after dental augmentation with demineralized bone matrix putty Comparison of an allograft in an experimental putty carrier and a bovine-derived xenograft used in ridge preservation: a clinical and histologic study in humans Extraction ridges and implantation of hydroxyapatite with membrane barriers: a histologic study Medical grade calcium sulphate hemihydrate in healing of human extraction ridges: clinical and histological observations at 3 mo Randomized study evaluating recombinant human bone morphogenetic protein-2 for extraction ridge augmentation Acellular dermal matrix and hydroxyapatite in prevention of ridge deformities after tooth extraction Titanium membranes in prevention of alveolar collapse after tooth extraction Immediate bone augmentation after infected tooth extraction using titanium membranes Xenograft versus extraction alone for ridge preservation after tooth removal: a clinical and histomorphometric study Preservation of the postextraction alveolar ridge: a clinical and histologic study Bone formation following implantation of bone biomaterials into extraction sites Magnesium-enriched hydroxyapatite compared with calcium sulfate in the healing of human extraction ridges: radiographic and histomorphometric evaluation at 3 mo Sandor et al Primary closure and bony defects on the ridge Norton et al Primary closure and augmented sites Babbush et al Primary closure and augmented sites Vance et al Primary closure Froum et al Primary closure Guarnieri et al Primary closure Fiorellini et al Primary closure and no buccal wall Luczyszyn et al Full-thickness flap elevation and periodontal teeth Pinho et al Primary closure Kfir etal Primary closure Barone et al Primary closure Cardaropoli and 2008 Posterior teeth Cardaropoli 34 Molly et al Primary closure Crespi et al Primary closure (soft tissue graft) and no buccal wall Ridge bone maintenance in human after extraction Casado et al Primary closure Ridge preservation following tooth extraction: a comparison between atraumatic extraction and ridge seal surgery Oghli and Steveling Primary closure (soft tissue graft) and no buccal wall Buccal plate augmentation: a new alternative to ridge preservation Caiazzo et al case reports, no measurements Corticocancellous porcine bone in the healing of human extraction ridges: combining histomorphomerty with osteoblast gene expression profiles in vivo Crespi et al Molar teeth extractions Ridge preservation using a composite bone graft and a bioabsorbable membrane with and without primary wound closure: a comparative clinical trial Analysis of tissue neogenesis in extraction ridges treated with GBR: clinical, histologic, and micro-ct results Histologic comparison of healing after ridge preservation using human demineralized bone matrix putty with one versus 2 different-sized bone particles Engler-Hamm 2011 Posterior teeth and primary et al 41 closure in one group Neiva et al Primary closure Hoang and 2012 Primary closure Mealey 43 3 months after tooth extraction. Whenever a series of articles reported the same study, the article that included the clinical measurements and/or details about implant placement was selected. Only included were studies of RP for single-rooted teeth or bicuspids for which primary closure was not obtained. Animal studies were thus excluded because they do not include single-root teeth, and the healing phase in animals is different from that in humans. Full-thickness flap was included to evaluate the thickness of the bone and bone architecture (Table 1). From each included study, the following data were obtained: number of patients and treated sites, position of sites, augmentation methods for test and control sites, observation period,

4 Table 2. Characteristics of the Included Studies Study Method Participants Teeth Smoking Howell et al 44 CCT 12 patients Maxillary premolars and forward No 16-wk follow-up 6 RP of single root teeth and 6 bone augmentation No control group Camargo et al 45 CCT 16 patients Anterior or premolar d Split-mouth design 6-mo follow-up Iasella et al 46 RCT 12 patients. Premolars and anterior teeth only 11 maxillary premolars, 6 maxillary incisors, 1 maxillary canine, 6 mandibular premolars 2 study groups Parallel 4 6 mo of follow-up Serino et al 47 CT 2 study groups 45 patients Upper and lower premolars, upper incisors, upper canines 6-mo follow-up Periodontal status: periodontitis Wang and Tsao 48 CCT 5 patients 2 upper premolars, 2 upper laterals and d 1 upper central 5 6 mo of follow-up No control group Neiva et al 49 RCT 24 patients. Maxillary premolars Maxillary premolars No 2 study groups Parallel 4-mo follow-up Serino et al 50 CT 2 study groups 20 patients. Monoradicular tooth Upper and lower premolars, incisors, and canines 3-mo follow-up Periodontal status: periodontitis Aimetti et al 51 RCT 40 patients Anterior maxilla No 2 study groups Parallel 3-mo follow-up Mardas et al 52 RCT 26 patients Maxillary or mandibular incisors, canine, or premolars Yes d d Yes but no heavy smokers (.10 cigarette per day) 2 study groups Single root teeth or bicuspids Parallel 8-mo follow-up Beck and Mealey 53 CCT 40 patients 24 sites in maxilla and 14 in mandible Yes 6-mo follow-up No control group Single root teeth (continued on next page) 702 RIDGE PRESERVATION TECHNIQUES BRANDAM ET AL

5 Table 2. (Continued) Study Method Participants Teeth Smoking Wood and Mealey 54 RCT 40 patients. Single root teeth (nonmolars) 2 study groups Parallel 5-mo follow-up 11 maxillary incisors, 4 maxillary canines, 11 maxillary premolars, 6 mandibular premolars Periodontal Status Surgical Considerations Intervention Measurement Method Outcome 2 teeth with periodontal bone loss. No active periodontitis Full-thickness flap. Extraction, debrided, and decortication of the ridge with 1/2 bur. No primary closure Test: application of the rhbmp- 2/ACS into the ridge d Flaps replaced in original position Test: bioactive glass and Casulfate Control: clot Periodontal probe, PA x-rays, and CT scan Pins for fixed reference No Better than complete infill of the ridge Test with more internal ridge fill, less resorption in height, and similar resorption in width compared with controls d Full-thickness mucoperiosteal flap Control: extraction alone Clinical + stent 9.2 mm initial and after 4 mo 8.0 mm in RP; and 9.1 mm and 6.4 in extraction only Atraumatic extraction Test: RP FDBA mm Histologic analysis from biopsy particle size, and a collagen membrane No primary closure Teeth with bone loss No primary closure Test: bioabsorbable sponge of polylactide-polyglycolide acid, Fisiograft Yes Atraumatic extraction. Ridge perforated with round bur. No primary closure Control: natural healing Ridges filled with FDBA (Puros) and CollaPlug Biopsy was taken Re-entry surgery at 6 mo + stent Results showed less bone height resorption on the T sites (t sites +0.2 [1.5] and c sites 0.7 [1.2]) Biopsy taken Histologic analysis Vital bone 68.5% average, 3.8% graft particles and 27.7% CT/bone marrow (continued on next page) BRANDAM ET AL IMPLANT DENTISTRY / VOLUME 24, NUMBER

6 Table 2. (Continued) Periodontal Status Surgical Considerations Intervention Measurement Method Outcome Yes Atraumatic extraction with Clinical measurements and degranulation customized acrylic templates Yes, teeth with bone loss Caries, root fracture, and residual roots No periodontal disease No periodontal disease Full-thickness flap elevation Test: putty P-15 and a bioabsorbable collagen wound dressing material Control: bioabsorbable collagen wound dressing material only Test: polylactide-polyglycolide acid, Fisiograft Biopsy taken Histological analysis No statistical significant between the ridge width in control and test sites; but there is a statistical significant in height At the time of the implant placement, no particles of the grafted material were identified. No mention on the article about the vertical and horizontal changes of the ridge No primary closure Control: natural healing No primary closure Test: MGCSH Re-entry at 3 mo and stent Vertical resorption and reduction of the width were more pronounced at control sites than at MGCSH sites (1.2 versus 0.5 mm, and 3.2 versus 2.0 mm, respectively) Full-thickness mucoperiosteal flap. Atraumatical extraction. Flaps were secured without primary closure Atraumatic extraction. Graft non freeze-dried cancellous mineralized human bone allograft ( mm). Bioabsorbable collagen wound dressing was placed on the top of the graft Control: no ridge filling Biopsy was taken Test: SBC Biopsy was taken Buccolingual width $ baseline 8 mm and 7 at 8 mo (SBC); baseline 9 mm and 6.9 at 8 mo (DBBM) Control: DBBM (Bio-Oss) In both groups a resorbable bilayer collagen barrier (Bio- Glide) was placed Group 1: 20 delayed healing group. Group 1: 20 early healing group Implant placement within 3 6 wk after CT scan Periodontal probe and sharp calipers Cone beam CT scan No statistical significant difference between groups for any histologic parameter was identified (continued on next page) 704 RIDGE PRESERVATION TECHNIQUES BRANDAM ET AL

7 Table 2. (Continued) Periodontal Status Surgical Considerations Intervention Measurement Method Outcome No less than 10 mm of bone PA, periapical. Atraumatic extraction Group 1: DFDBA Cone beam CT scan No significant differences when comparing changes in the alveolar ridge dimensions of each group No flap Group 2: FDBA Clinical measurements with calipers No primary closure Collagen membrane over either graft material Implant placed wk after the RP No control group Table 3. Characteristics of the Included Studies Author Representative Population Eligibly Criteria Defined Randomization Blinded Reported Loss to Follow-up No. of (%) Dropouts Howell et al 44 No Yes d d No 0 No High Camargo et al 45 Yes Yes d d Yes 0 Yes High Iasella et al 46 Yes Yes d d Yes 0 Yes High Serino et al 47 Yes Yes Yes Yes Yes 9 (20%) Yes Low Wang and Tsao 48 No No No No No 0 No High Neiva et al 49 Yes Yes Yes Yes?? Yes Moderate Serino et al 50 Yes Yes Yes Yes Yes 4 (20%) Yes Low Aimetti et al 51 Yes Yes Yes Yes Yes 0 Yes Moderate Mardas et al 52 Yes Yes Yes d Yes 4 (13%) Yes Moderate Beck and Yes Yes No d Yes 7 (17%) No High Mealey 53 Wood and Mealey 54 Yes Yes Yes No Yes 7 (17%) No Moderate Control Group Risk of Bias BRANDAM ET AL IMPLANT DENTISTRY / VOLUME 24, NUMBER

8 Table 4. Characteristics of the Included Studies Followup, (mo) Intervention Baseline (mm) End (mm) Change in Height (mm) Change in Width (mm) Authors Measurement P Howell et al 44 Periodontal probe, PA 4 Test: rhbmp-2/acs into?? mm?? x-rays, and CT scan the ridge d d d d d d Camargo Pins for fixed 6 Test: bioactive glass and 7.86 (60.68) 4.38 (60.43) NSS et al 45 reference calcium sulfate Control: clot 7.50 (60.74) 4.44 (60.27) NSS Iasella et al 46 Clinical + stent 4 6 Test: FDBA ,0.05 Histologic Analysis Control: clot ,0.05 from biopsy Serino et al 47 Reentry surgery at 6?? ?,0.01 mo + stent 6 Test: bioabsorbable sponge of polylactidepolyglycolide acid, Fisiograft Biopsy taken Control: clot?? ?,0.01 Wang and Tsao 48 Histologic analysis 5 6 FDBA????? d d d d d d Neiva et al 49 Clinical measurements and customized acrylic templates Biopsy taken 4 Test: putty P-15?? NSS width, P, 0.05 height Control: bioabsorbable collagen wound dressing Serino et al 50 Histological analysis 3 Test: polylactidepolyglycolide acid, Fisiograft?? NSS width, P, 0.05 height????? Control: clot????? Aimetti et al 51 Reentry at 3 mo and 3 Test: MGCSH ,0.05 stent Biopsy was taken Control: clot ,0.05 Mardas et al 52 Biopsy was taken 8 Test: SBC ,0.05 width, NSS height Control: DBBM (Bio-Oss) ,0.05 width, NSS height Beck and Mealey 53 Periodontal probe and sharp calipers 6 Group 1: 20 delayed healing group Cone beam CT scan 3 Group 1: 20 early healing group 9.38 mean? NSS 8.47 mean? NSS Wood and Mealey 54 Cone beam CT scan 5 Group 1: DFDBA ? ( 22.8%) Clinical measurements Group 2: FDBA ? with calipers ( 20.9%) NSS, not statistically significant; PA, periapical. NSS NSS 706 RIDGE PRESERVATION TECHNIQUES BRANDAM ET AL

9 BRANDAM ET AL IMPLANT DENTISTRY / VOLUME 24, NUMBER Table 5. Evaluation of the Studies According to the Grafting Materials Summary Height Width Difference in Width (mm) Between Test/Control P Difference in Height (mm) Between Test/Control P Follow-up, (mo) Method Intervention Authors Camargo et al NSS 0.42 NSS + Filler Bioactive glass and calcium sulphate FDBA Iasella et al , , FDBA Wang and 5 6?????? Tsao 48 Putty P-15 Neiva et al , NSS + + MGCSH Aimetti et al , , SBC Mardas et al * NSS 1.1*,0.05?? DBBM Mardas et al * NSS 2.1*,0.05?? Beck and * NSS 1.47* NSS + + Mealey 53 Mineralized human bone allograft * NSS 1.43* NSS + FDBA * NSS 2.09* NSS?? 0.37* NSS 2.18* NSS?? Wood and Mealey 54 DFDBA Wood and Mealey 54 Growth factor rhbmp-2/acs Howell et al ??? +? Sponge polylactide-polyglycolide acid Serino et al ,0.01?? +? polylactide-polyglycolide acid Serino et al 50 3?????? *No clot as a control group. Difference between baseline and final outcome. NSS, not statistically significant. and complications. The primary outcome evaluated was the change in ridge dimensions after tooth extraction and ridge-preservation therapy, measured as the change in the height and width of the alveolar process in millimeters or as a percentage. The secondary outcome was the success of the implant placement and the amount of grafting material found in the grafted site during the procedure. RESULTS A total of 223 studies initially were identified, from which 55 full-text articles were further examined. Of those, 11 studies met the inclusion criteria These publications are briefly described in Table 2. Five studies were RCTs with 2 study groups and a follow-up period of between 3 and 8 months. 46,49,51,52,54 Six studies were controlled clinical trials. 44,45,47,48,50,53 Of these, 3 had a test and control group. 45,47,50 Only 1 study used a split-mouth design, 45 whereas the others all were parallel designs. All studies had a follow-up period of at least 3 months. The study populations ranged from 5 to 45 individuals. Smoking habits were described in 3 studies, 46,52,53 whereas smokers were excluded from 4 studies. 44,49,51,54 The other 4 studies did not mention the subjects smoking status. 45,47,48,50 Full-thickness buccal and lingual flaps were elevated in most of the studies, 44 50,52 whereas 3 studies attempted RP without opening a flap. 51,53,54 In all the studies, the extraction ridges were carefully debrided before any graft material was inserted. None of the studies used primary closure. In all the studies in which full-thickness flaps were elevated, the tissue was sutured in its original position without advancing it to achieve primary closure. The reasons for extraction varied and included caries, 44,51,53 periodontal bone loss, 44,47,50 periodontal disease, 48 nonrestorable roots, 44,51 tooth fracture, 48,51,53 and endodontic complications. 48,52,53 Some studies did not specify the causes of tooth extraction. 45,46,49,54 Atraumatic extraction was reported on different studies. 45,46,48,49,51 54

10 708 RIDGE PRESERVATION TECHNIQUES BRANDAM ET AL Table 6. Histological Results of the Studies Authors Graft Material Site % Bone % Graft Material % Trabecular Bone % Connective Tissue Iasella et al 46 FDBA Preservation ? Extraction alone d ? Serino et al 47 Sponge Preservation ?? Extraction alone d?? Wang and Tsao 48 FDBA Preservation Neiva et al 49 Putty P-15 Preservation ? Collagen dressing d ? Serino et al 50 Sponge Preservation ?? Extraction alone d?? Aimetti et al 51 MGCSH Preservation? ? Extraction alone? d ? Mardas et al 52 SBC Preservation???? DBBM Preservation???? Beck and Mealey 53 Mineralized human bone allograft 3 mo preservation ? mo preservation ? Wood and Mealey 54 DFDBA Preservation ? FDBA Preservation ? Decortication with a bur was performed by 2 groups. 44,48 The other researchers did only degranulation of the ridge but not decortication. Some authors 44 46,51 54 prescribed antibiotics for at least 1 week after extraction(s) and RP. Bone Grafting Materials Graft material was used alone in some studies 44,45,47,50,51 and in combination with a membrane in others. 46,48,49,52 54 Filler materials were used in most of the studies. 45,46,48,49,51 54 Sponges (bioabsorbable polylactide-polyglycolide acid) were used in 2, 47,50 and a growth factor (rhbmp-2/acs) was used only in 1 study 44 (Table 3 5). Among the fillers, human bone allograft was used most commonly. 46,48,53,54 This included freeze-dried bone allograft (FDBA), 46,48,54 mineralized non freezedried allograft, 53 and demineralized freeze-dried bone allograft (DFDBA). 48 One group 52 used the xenograft demineralized bovine bone mineral (DBBM). Alloplasts used in the studies 45,49,51,52 were bioactive glass, hydroxyapatite, and medical-grade calcium sulfate hemihydrate (MGCSH). Dimensional changes in the ridges were assessed by clinical, radiographic, or acrylic stent examination, or some combination of those. Three groups 44,53,54 used computed tomographic scanning, whereas other means of assessment included intraoperative measurement of the width of the alveolar ridge at the time of re-entry, 47,51 the use of acrylic stents, 46,47,49 51 and the use of titanium pins on the outer surface of the buccal bone as a reference. 45 Eight of the groups used histological analysis to identify new bone formation in the ridge. The quality of the studies was assessed by considering the following factors: whether the study population was representative, whether eligibility criteria were defined, whether treatment was randomized and blinded, whether loss to follow-up was reported (along with the percentage of drop-outs), and whether a control group was included. Based on these factors, the risk of bias for each study was determined, and 5 studies were considered to have a high risk of being biased ,53 Four studies were considered to have a moderate

11 BRANDAM ET AL IMPLANT DENTISTRY / VOLUME 24, NUMBER Table 7. Final Clinical Outcome Secondary Bone Augmentation Histology Comments Time After Extraction, (mo) Implant Placement Authors Graft Material Yes Some sites with dehiscence requires secondary bone augmentation Iasella et al 46 FDBA Yes 4 6 Some sites with dehiscence Yes 3 and 6 4/38 implants Yes 34/38 good primary stability. 4/38 insufficient bone width Serino et al 47 Sponge Yes 6 NA Yes Good primary stability in all of the implants Wang and Tsao 48 FDBA Yes 5 6 NA Yes d Neiva et al 49 Putty P-15 Yes 4 NA Yes One implant has not had primary stability in the control group Serino et al 50 Sponge Yes 3 NA Yes Good primary stability in all C and T groups Aimetti et al 51 MGCSH Yes 3 NA Yes No radiographically difference between the bone in C and T groups Mardas et al 52 SBC Yes 8 9/13 implants Yes Bone resistance during trephination was similar for both groups. One patient in DBBM group had no primary stability, and the implant placement was not possible DBBM Yes 8/12 implants Beck and Mealey 53 Mineralized human bone allograft Wood and Mealey 54 DFDBA Yes 5 NA Yes Good primary stability in all of the implants. One subject did not have enough bone width for implant placement FDBA Yes NA Yes risk, 49,51,52,54 with only 2 studies considered to have a low risk (Table 2). 47,50 Bone Dimension Outcomes Table 3 displays the changes in the extraction-ridge height and/or, as reported in 9 of the studies. Two of the studies used only histological analysis and did not record the ridge dimensions. Those that compared the use of a ridgepreservation technique with natural healing 45 47,50,51 showed that the height of the alveolus in the test groups was better preserved, that is, the average height of the alveolar process of the control group was significantly lower than that of the test group. Overall, the control groups showed a change in the alveolar height ranging between 1.2 and 0.2 mm, whereas the ridge-preservation group was more heterogeneous, demonstrating vertical bone loss that ranged between 0.57 and 1.3 mm. Differences between test and control groups were found to be statistically significant by the authors in 4 studies. 46,47,49,51 Mardas et al 52 found a statistically significant difference between the baseline and outcome values of both groups treated (with Straumann ceramic bone and DBBM). Three studies 45,46,51 measured the change in the width in test group extraction ridges and control group extraction ridges that healed naturally. The reduction of the ridge width in the control groups ranged between 3.2 and 3.06 mm, whereas in the test groups it ranged between 2 and 3.48 mm. Histological Outcomes Nine of 11 studies examined the histology of biopsies from the graft sites. Four studies 46,47,50,51 analyzed the test and control ridges histomorphometrically and showed similar results, with approximately 50% new bone formation (Table 6). Among the 3 studies that used FDBA as a graft material, 46,48,54 the results reported by Iasella et al 46 and Wood and Mealey 54 were similar (% bone: / and % graft material: / , respectively), but they differed from those reported by Wang et al 48 (% bone: 68.5 and % graft material: 3.8). Wood and Mealey 54 also analyzed results from using DFDBA and found

12 710 RIDGE PRESERVATION TECHNIQUES BRANDAM ET AL a higher percentage of bone and a lower percentage of graft particles in that group than the FDBA group. Three studies 47,50,51 found no remaining graft material at the time of the biopsy, after using a bioabsorbable sponge of polylactide-polyglycolide acid as a graft material 47,50 and calcium sulfate. 51 Neiva et al 49 found a lower percentage of bone in the group augmented with P-15 putty ( ) than in the control group, which had received only a collagen dressing ( ). Implant-Related Outcomes The objective of RP is to make it possible to later place implants with ideal diameters in the ideal positions. Although the studies included in this review reported placing implants at various times after extraction in sites grafted with a variety of materials, none of them reported the size of the implants or whether they were placed in the ideal position. Nine of the 11 studies reported on implant placement (Table 7). The other 2 studies did not, nor did they analyze the histology of the preserved site. None of the studies specified whether implants were placed in the test or control group, but many implants were satisfactorily placed in both groups. 47,50,51 Primary implant stability was achieved in almost all of the implants. Some subjects did not have enough width after the RP, and implants could not be placed without secondary bone augmentation. 46,52 54 DISCUSSION To create implant-supported dental prostheses that function ideally and have excellent esthetics, the implants must be in the correct 3-dimensional position. Sufficient alveolar bone volume and a favorable ridge architecture are essential to achieving this. Otherwise, an inappropriate restoration-implant alignment may result, complicating restorative treatment. The aim of extraction-rp is to maintain the vertical and horizontal bone and the integrity of the soft tissue to enable later placement of implants that are optimally dimensioned and positioned. It is well known that the alveolar ridge tends to resorb after tooth extraction. This resorption typically affects the buccal wall, with the alveolar crest shifting lingually. 55 Given this and the fact that the majority of anterior maxillary buccal walls have a width of 0.5 to 1 mm, 55,56 any postextraction collapse of the alveolar bone width and height can be expected to significantly affect future implant placement. A question that arises is whether RP is indicated if there are sufficient bone walls and no infection is present. Can placing an implant immediately in the fresh extraction ridge limit the resorption? A number of previous studies have addressed this question However, these studies do not demonstrate that immediate implant placement predictably controls either buccal wall resorption or soft-tissue recession, and thus esthetic outcomes are unpredictable. Among the techniques proposed for RP is primary closure of the ridge. Bone loss is a well-recognized consequence of flap elevation. 55 It is known that after a flap procedure, there is evidently bone loss, and this bone loss depends on the alveolar ridge architecture. Patients with thin buccal bone are particularly likely to experience significant bone loss, because of the high osteoclastic activity. 55 When RP was evaluated in 2011 with and without primary closure, 55 the researchers concluded that the width of ridges treated without primary closure decreased by 24%, compared with 28% in the primary closure group. Moreover, the RP without primary closure better preserved the keratinized mucosa and resulted in less postoperative patient discomfort. The concept of RP to maintain the ridge for future implant must be differentiated from guided bone regeneration (GBR), in which a grafting material and a barrier membrane are placed and primary closure is achieved. 55 In general, GBR is indicated if an augmentation or corrective surgery of a defect for a future implant placement is planned. RP is indicated if the ridge is intact, and the objective to preserve as much tissue as possible in preparation for future implant placement. No fenestrations, dehiscences, sinus communication, periodontal pockets, or apical pathology should be present. The literature suggests that some confusion between RP and the GBR technique exists. Therefore, the authors propose a new definition of ridge preservation : a procedure in which grafting material is placed in the intact alveolus after atraumatic tooth extraction, without flap elevation, to preserve the alveolar ridge, with the final objective of an implant placement in the ideal position. A related question is the ideal time for implant placement after the RP. Although researchers have found extractions ridges to be substantially filledat40days 55 and completely filled at 10 weeks, 55 when biopsies from grafted ridges were compared at 3 and 6 months, 53 no statistically significant difference in the percentage of bone and graft material present was found. The authors believe that 3 months is a reliable healing time for achieving good primary stability of the implant and subsequent osseointegration. Future studies are planned to answer this question. The literature is conspicuously silent regarding the outcomes of implant rehabilitation after RP. Implants have been placed in sites where RP was undertaken and in control sites, but there is a lack of information about the tridimensional positioning of those implants, as well as how deeply or shallowly the placement was, relative to adjacent teeth. Similarly, the role of implant design, important especially in the anterior esthetic zone, is unexamined. CONCLUSION The studies reviewed used different preservation techniques, grafting materials, and healing times, but all of them found less vertical and horizontal ridge contraction at grafted extraction sites than at nongrafted ones. Depending on the graft material and technique, some degree of residual graft was found, as well as new bone formation. The use of membranes seemed to optimize final outcomes. Three months seems to be a sufficient healing time after RP to enable new bone formation that will

13 BRANDAM ET AL IMPLANT DENTISTRY / VOLUME 24, NUMBER allow for placement of implants with good primary stability. The studies reviewed did not provide evidence of superiority of one graft material over another. Furthermore, they provided no data regarding the impact of RP on esthetic outcomes or long-term implant outcomes. Such data are still needed. DISCLOSURE The authors claim to have no financial interest, either directly or indirectly, in the products or information listed in the article. REFERENCES 1. Hoad-Reddick G, Grant AA, McCord JF. Osseoretention? Comparative assessment of particulate hydroxyapatite inserted beneath immediate dentures. Eur J Prosthodont Restor Dent. 1994;3: Becker W, Becker BE, Caffesse R. A comparison of demineralized freezedried bone and autologous bone to induce bone formation in human extraction ridges. J Periodontol. 1994;65: Becker W, Urist M, Becker B. 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