Ridge Preservation After Tooth Extraction With Buccal Bone Plate Deficiency Using Tunnel Structured β‐Tricalcium Phosphate Blocks: A 2‐Month Histologic Pilot Study in Beagle Dogs

Background: Reduction in alveolar ridge volume is a direct consequence of tooth extraction. Tunnel β‐tricalcium phosphate (β‐TCP) blocks were manufactured from randomly organized tunnel‐shaped β‐TCP ceramic. Efficacy of these blocks compared to extraction alone for alveolar ridge preservation after tooth extraction with buccal bone deficiency was evaluated. Methods: Maxillary first premolars of six beagle dogs were extracted after removing the buccal bone, and bone defects of 4 × 4 × 5 mm (mesio‐distal width × bucco‐palatal width × depth) were created. Fresh extraction sockets with buccal bone defects were filled with tunnel β‐TCP blocks at test sites. Two months after the operation, histologic and histometric evaluations were performed. Results: Regarding histologic sections, coronal and middle horizontal widths of the alveolar ridge were significantly greater at test sites (3.2 ± 0.5 and 3.6 ± 0.4 mm, respectively) than at control sites (1.2 ± 0.3 and 2.0 ± 0.6 mm, respectively). The amount of woven bone was significantly greater at test sites (62.4% ± 7.9%) than at control sites (26.8% ± 5.3%), although that of connective tissue and bone marrow was significantly greater at control sites (38.1% ± 6.2% and 16.0% ± 6.9%, respectively) than at test sites (10.7% ± 5.7% and 4.1% ± 2.2%, respectively). Regarding basic multicellular units, no statistically significant difference was found between the test and control sites (0.5% ± 0.1% and 0.6% ± 0.1%, respectively). Conclusion: Tunnel β‐TCP blocks represent an effective bone‐graft material for alveolar ridge preservation in fresh extraction sockets with buccal bone defects.     

Porcine‐Derived Xenograft Combined with a Soft Cortical Membrane versus Extraction Alone for Implant Site Development: A Clinical Study in Humans

Background: An adequate alveolar crest is essential for implant placement in terms of esthetics and function. The objective of this randomized clinical trial was to compare the preservation of the alveolar ridge dimensions following tooth extraction using porcine‐derived xenograft combined with a membrane versus extraction‐alone (EXT) sites. Methods: Fifteen patients who required double extraction of contralateral premolars and delayed implant placement were randomly selected to receive both ridge‐preservation procedure and EXT. The test sites (alveolar ridge preservation [ARP]) included 15 sockets treated using a corticocancellous porcine bone xenograft (OsteoBiol® Gen‐Os; Tecnoss srl, Giaveno, Italy) associated with a soft cortical membrane (OsteoBiol® Lamina; Tecnoss srl), while the corresponding control sites (EXT) were left without grafting for EXT. Horizontal and vertical ridge dimensions were recorded at baseline and 6 months after extractions. Results: After 6 months, the EXT sites showed a significantly greater reabsorption of the buccolingual/palatal dimension of the alveolar ridge (3.7 ± 1.2 mm) compared with the ARP sites (1.8 ± 1.3 mm). The mean vertical ridge height reduction in the control sockets was 3.1 ± 1.3 mm at the buccal sites and 2.4 ± 1.6 mm at the lingual sites compared with 0.6 ± 1.4 and 0.5 ± 1.3 mm, respectively, in the test sockets. The differences between test and control sockets were not significant for the mesial and distal measurements. Conclusions: The placement of a porcine xenograft with a membrane in an extraction socket can be used to reduce the hard tissue reabsorption after tooth extraction compared with EXT.     

上颌单颗前牙位点保存后邻面牙槽嵴高度的早期变化

目的 探讨位点保存术对上颌单颗前牙拔除后邻面牙槽嵴高度早期变化的影响,为种植修复龈乳头美学效果提供参考依据。方法 选择需拔除上颌单颗前牙的30例患者为研究对象,将其随机分为试验组和对照组,每组15例。试验组在拔牙同时进行位点保存术（牙槽窝内植入 Bio-Oss骨粉,表面游离龈移植缝合固定）,对照组拔牙后未行其他处理。术后7 d及术后6个月,佩戴个性化数字化放射导板行锥形束CT检查,测量2组近远中邻面牙槽嵴及唇侧中央牙槽嵴高度的变化。结果 试验组近中、远中邻面及唇侧中点的牙槽嵴吸收高度分别为（0.358±0.151）mm、（0.322±0.180）mm、（0.826±0.307）mm,对照组近远中邻面及唇侧中点的牙槽嵴吸收高度分别为（0.653±0.260）mm、（0.667±0.274）mm、（1.510±0.625） mm。统计分析表明,试验组的牙槽嵴吸收高度小于对照组（P<0.05）,近中、远中邻面牙槽嵴的吸收高度均小于唇侧（P<0.05）。结论 位点保存术可以减少牙拔除后牙槽嵴高度的吸收,提高种植修复龈乳头美学效果。     

上颌单颗前牙位点保存后邻面牙槽嵴高度的早期变化

目的 探讨位点保存术对上颌单颗前牙拔除后邻面牙槽嵴高度早期变化的影响,为种植修复龈乳头美学效果提供参考依据。方法 选择需拔除上颌单颗前牙的30例患者为研究对象,将其随机分为试验组和对照组,每组15例。试验组在拔牙同时进行位点保存术（牙槽窝内植入 Bio-Oss骨粉,表面游离龈移植缝合固定）,对照组拔牙后未行其他处理。术后7 d及术后6个月,佩戴个性化数字化放射导板行锥形束CT检查,测量2组近远中邻面牙槽嵴及唇侧中央牙槽嵴高度的变化。结果 试验组近中、远中邻面及唇侧中点的牙槽嵴吸收高度分别为（0.358±0.151）mm、（0.322±0.180）mm、（0.826±0.307）mm,对照组近远中邻面及唇侧中点的牙槽嵴吸收高度分别为（0.653±0.260）mm、（0.667±0.274）mm、（1.510±0.625） mm。统计分析表明,试验组的牙槽嵴吸收高度小于对照组（P<0.05）,近中、远中邻面牙槽嵴的吸收高度均小于唇侧（P<0.05）。结论 位点保存术可以减少牙拔除后牙槽嵴高度的吸收,提高种植修复龈乳头美学效果。     

Alveolar ridge preservation with guided bone regeneration and a synthetic bone substitute or a bovine‐derived xenograft: a randomized,controlled clinical trial

Objectives: The aim of this randomized, controlled clinical trial was to compare the potential of a synthetic bone substitute or a bovine‐derived xenograft combined with a collagen membrane to preserve the alveolar ridge dimensions following tooth extraction. Methods: Twenty‐seven patients were randomized into two treatment groups following single tooth extraction in the incisor, canine and premolar area. In the test group, the alveolar socket was grafted with Straumann Bone Ceramic^® (SBC), while in the control group, Bio‐Oss^® deproteinized bovine bone mineral (DBBM) was applied. In both groups, a collagen barrier was used to cover the grafting material. Complete soft tissue coverage of the barriers was not achieved. After 8 months, during re‐entry procedures and before implant placement, the horizontal and vertical dimensions of the residual ridge were re‐evaluated and trephine biopsies were performed for histological analysis in all patients. Results: Twenty‐six patients completed the study. The bucco‐lingual dimension of the alveolar ridge decreased by 1.1±1 mm in the SBC group and by 2.1±1 in the DBBM group (P<0.05). Both materials preserved the mesio‐distal bone height of the ridge. No differences in the width of buccal and palatal bone plate were observed between the two groups. The histological analysis showed new bone formation in the apical part of the biopsies, which, in some instances, was in direct contact with both SBC and DBBM particles. The coronal part of the biopsies was occupied by a dense fibrous connective tissue surrounding the SBC and DBBM particles. Conclusion: Both biomaterials partially preserved the width and the interproximal bone height of the alveolar ridge. To cite this article:
Mardas N, Chadha V, Donos N. Alveolar ridge preservation with guided bone regeneration and a synthetic bone substitute or a bovine‐derived xenograft: a randomized, controlled clinical trial.
Clin. Oral Impl. Res. 21 , 2010; 688–698.     

Advanced platelet‐rich fibrin and freeze‐dried bone allograft for ridge preservation: A randomized controlled clinical trial

1 Background

Advanced platelet‐rich fibrin (A‐PRF) is an autogenous blood product with applications in dento‐alveolar surgery. However, there is minimal information regarding its optimal clinical application or efficacy. The aim of this multi‐arm parallel randomized controlled clinical trial was to evaluate the efficacy of A‐PRF alone or with freeze‐dried bone allograft (FDBA) in improving vital bone formation and alveolar dimensional stability during ridge preservation.

2 Methods

Forty patients requiring extraction of non‐molar teeth and replacement with dental implants were randomized into one of four ridge preservation approaches: A‐PRF, A‐PRF+FDBA, FDBA, or blood clot. A‐PRF was prepared at 1,300 rpm for 8 minutes. Non‐traumatic extractions and ridge preservation was performed. After an average of 15 weeks healing, bone core samples were harvested at the time of implant placement for micro‐CT and histomorphometric analysis. Ridge dimensions were measured immediately after extraction and before implant placement.

3 Results

Significantly greater loss of ridge height was noted in the blood clot group (3.8 ± 2.0 mm) compared to A‐PRF (1.8 ± 2.1 mm) and A‐PRF+FDBA (1.0 ± 2.3 mm) groups (P < 0.05). No significant differences in ridge width reduction were noted between groups. Significantly more vital bone was present in the A‐PRF group (46% ± 18%) compared to the FDBA group (29% ± 14%) (P < 0.05). Bone mineral density was significantly greater in the FDBA group (551 ± 58 mg/cm³) compared to blood clot (487 ± 64 mg/cm³) (P < 0.05).

4 Conclusions

This study demonstrates A‐PRF alone or augmented with FDBA is a suitable biomaterial for ridge preservation. This study represents the first randomized controlled clinical trial comparing A‐PRF with and without FDBA to FDBA alone for ridge preservation.     

Evaluation of Healing at Molar Extraction Sites With and Without Ridge Preservation: A Randomized Controlled Clinical Trial

Background: To date, limited evidence is available specifically evaluating ridge preservation (RP) and implant placement in molar sites. The primary aim of this study is to radiographically compare alveolar ridge changes with and without RP with cone‐beam computed tomography (CBCT). Methods: This parallel, two‐arm randomized clinical trial included 40 patients evenly distributed between two treatment groups. After molar extraction, sites were allowed to heal naturally or received RP with freeze‐dried bone allograft covered by a non‐resorbable dense polytetrafluoroethylene membrane. CBCT scans were taken immediately and 3 months postextraction, and then a dental implant was placed. Width and height measurements were made radiographically. Results: Significantly greater loss in alveolar ridge height was found in molar sites allowed to heal without RP on the buccal aspect of the socket (RP: ?1.12 ± 1.60 mm versus no RP: ?2.60 ± 2.06 mm, P = 0.01). No significant difference in ridge width loss was found between groups. Two‐thirds ridge width reduction was experienced on the buccal aspect in sites without RP, but width loss was evenly distributed between buccal and lingual aspects when RP was performed. Bone grafting at time of placement was required in 25% of implants in the group without RP versus 10% of implants in the RP group. Conclusions: In molar extraction sites without RP, significantly more reduction in ridge height occurred, and the majority of ridge width loss was localized to the buccal aspect. When RP was performed, ridge width loss was not significantly decreased, but the loss was evenly distributed between facial and lingual aspects of the extraction site.     

Effect of Single and Contiguous Teeth Extractions on Alveolar Bone Remodeling: A Study in Dogs

Background: Tooth extraction is associated with dimensional changes in the alveolar ridge. The aim was to examine the effect of single versus contiguous teeth extractions on the alveolar ridge remodeling. Material and Methods: Five female beagle dogs were randomly divided into three groups on the basis of location (anterior or posterior) and number of teeth extracted – exctraction socket classification: group 1 (one dog): single‐tooth extraction; group 2 (two dogs): extraction of two teeth; and group 3 (two dogs): extraction of three teeth in four anterior sites and four posterior sites in both jaws. The dogs were sacrificed after 4 months. Sagittal sectioning of each extraction site was performed and evaluated using microcomputed tomography. Results: Buccolingual or palatal bone loss was observed 4 months after extraction in all three groups. The mean of the alveolar ridge width loss in group 1 (single‐tooth extraction) was significantly less than those in groups 2 and 3 (p < .001) (multiple teeth extraction). Three‐teeth extraction (group 3) had significantly more alveolar bone loss than two‐teeth extraction (group 2) (p < .001). The three‐teeth extraction group in the upper and lower showed more obvious resorption on the palatal/lingual side especially in the lower group posterior locations. Conclusion: Contiguous teeth extraction caused significantly more alveolar ridge bone loss as compared with when a single tooth is extracted.     

Deproteinized bovine bone mineral in marginal defects at implants installed immediately into extraction sockets: an experimental study in dogs

Aim: To evaluate the influence of deproteinized bovine bone mineral (DBBM) particles concomitant with the placement of a collagen membrane on alveolar ridge preservation and on osseointegration of implants placed into alveolar sockets immediately after tooth extraction. Material and methods: The pulp tissue of the mesial roots of ₃P₃ was removed in six Labrador dogs and the root canals were filled. Flaps were elevated in the right side of the mandible, and the buccal and lingual alveolar bony plates were exposed. The third premolar was hemi‐sectioned and the distal root was removed. A recipient site was prepared and an implant was placed lingually. After implant installation, defects of about 0.6 mm wide and 3.1 mm depth resulted at the buccal aspects of the implant, both at the test and at the control sites. The same surgical procedures and measurements were performed on the left side of the mandible. However, DBBM particles with a size of 0.25–1 mm were placed into the remaining defect concomitant with the placement of a collagen membrane. Results: All implants were integrated into mature bone. No residual DBBM particles were detected at the test sites after 4 months of healing. Both the test and the control sites showed buccal alveolar bone resorption, 1.8±1.1 and 2.1±1 mm, respectively. The most coronal bone‐to‐implant contact at the buccal aspect was 2±1.1 an 2.8±1.3 mm, at the test and the control sites, respectively. This difference in the distance was statistically significant. Conclusion: The application of DBBM concomitant with a collagen membrane to fill the marginal defects around implants placed into the alveolus immediately after tooth extraction contributed to improved bone regeneration in the defects. However, with regard to buccal bony crest preservation, a limited contribution of DBBM particles was achieved. To cite this article:
Caneva M, Botticelli D, Pantani F, Baffone GM, Rangel IG Jr, Lang NP. Deproteinized bovine bone mineral in marginal defects at implants installed immediately into extraction sockets: an experimental study in dogs.
Clin. Oral Impl. Res. 23 , 2012; 106–112.
doi: 10.1111/j.1600‐0501.2011.02202.x     

Buccal Bone Formation After Flapless Extraction: A Randomized,Controlled Clinical Trial Comparing Recombinant Human Bone Morphogenetic Protein 2/Absorbable Collagen Carrier and Collagen Sponge Alone

Background: Flapless extraction of teeth allows for undisturbed preservation of the nearby periosteum and a source of osteoprogenitor cells. Recombinant human bone morphogenetic protein 2 (rhBMP‐2) has been used for different bone augmentation purposes with great osteoinductive capacity. The aim of this study is to compare the bone regenerative ability of rhBMP‐2 on an absorbable collagen sponge (ACS) carrier to a collagen sponge (CS) alone in extraction sites with ≥50% buccal dehiscence. Methods: Thirty‐nine patients requiring extraction of a hopeless tooth with ≥50% buccal dehiscence were enrolled. After flapless extraction and randomization, either rhBMP‐2/ACS carrier or CS alone was placed in the extraction site. After extraction, a baseline cone beam computed tomography (CBCT) scan was obtained of the site, and a similar scan was obtained 5 months postoperatively. Medical imaging and viewing software were used to compare the baseline and 5‐month postoperative images of the study site and assess ridge width measurements, vertical height changes, and buccal plate regeneration. Results: Radiographically, CBCT analysis showed that with ≥50% of buccal bone destruction, rhBMP‐2/ACS was able to regenerate a portion of the lost buccal plate, maintain theoretical ridge dimensions, and allow for implant placement 5 months after extraction. The test group performed significantly (P <0.05) better in regard to clinical buccal plate regeneration (4.75 versus 1.85 mm), clinical ridge width at 5 months (6.0 versus 4.62 mm), and radiographic ridge width at 3 mm from the alveolar crest (6.17 versus 4.48 mm) after molar exclusion. There was also significantly (P <0.05) less remaining buccal dehiscence, both clinically (6.81 versus 10.0 mm) and radiographically (3.42 versus 5.16 mm), at 5 months in the test group. Significantly (P <0.05) more implants were placed in the test group without the need for additional augmentation. The mean loss in vertical ridge height (lingual/palatal) was less in the test sites but was not significantly (P = 0.514) different between the test and control groups (0.39 versus 0.64 mm). Conclusions: rhBMP‐2/ACS compared to CS alone used in flapless extraction sites with a buccal dehiscence is able to regenerate lost buccal plate, maintain theoretical ridge dimensions, and allow for implant placement 5 months later.     

Analysis of the pattern of the alveolar ridge remodelling following single tooth extraction

Introduction: Tooth extraction is followed by marked osseous changes of the residual alveolar ridge including severe bone alterations both in height and in width. However, such remodelling could jeopardize the subsequent implant insertion for two main reasons. Firstly, the absence of adequate bone levels makes implant placement impossible; secondly, aesthetic problems in the fabrication of implanto‐supported restoration could be caused by serious bone re‐absorption. Thus, it is of crucial importance that the dental surgeon knows how the alveolar crest changes when a single tooth has been removed. The aim of this study was to evaluate the pattern of alveolar crest remodelling observed in a single intercalated area of tooth extraction after at least a period of 6 months of healing, using standardized photos of model casts. Material and methods: Among the patients who were treated for a single intercalated tooth extraction during the last 2 years at the department of dentistry at Versilia Hospital, Lido di Camaiore (Lucca), Italy, we selected 50 patients. The amount of alveolar crest remodelling was assessed on standardized photos of study models. All measurement were recorded on an Excel sheet (Excel, Windows XP^®) and each value was multiplied by the enlargement index so that true values of re‐absorption could be obtained. Finally, we have calculated the percentage of amount of alveolar crest remodelling and shifting of alveolar crest. Results: We calculated the percentage of buccal remodelling and alveolar crest shift. The buccal re‐absorption was 19.4±9.4% at mesial point, 39.1±10.4% at midpoint and 20.3±10.7% at distal level. Moreover, the shift of the alveolar crest was 59.1±11.2% at mesial point, 64.8±10.5% at the midpoint and 56±12.5% at distal point. Conclusions: This study confirmed that buccal wall tends to re‐absorb after the extraction according to a specific pattern. Thus, the re‐absorption at the midpoint represent the double of bone loss at the distal and the mesial points. Furthermore, we have observed first how the alveolar crest shifts placing along the more lingual/palatal line which divides the original alveolar crest into three parts. To cite this article:
Covani U, Ricci M, Bozzolo G, Mangano F, Zini A, Barone A. Analysis of the pattern of the alveolar ridge remodelling following single tooth extraction.
Clin. Oral Impl. Res. 22 , 2011; 820–825
doi: 10.1111/j.1600‐0501.2010.02060.x     

Histologic comparison of healing after ridge preservation using human demineralized bone matrix putty with one versus two different-sized bone particles

Background: Ridge preservation can minimize the loss of alveolar bone subsequent to tooth extraction in preparation for implant therapy. The purpose of this study is to histologically and clinically compare human demineralized bone matrix (DBM) putty with one size of bone particles (SPS) to human DBM putty with two different sizes of bone particles (multiple particle sizes [MPS]) in ridge preservation after molar extractions. Methods: Molar tooth extraction and ridge preservation were performed in 20 participants for each treatment group. Approximately 20 weeks after grafting, core biopsies were obtained during implant placement and analyzed under light microscopy. Specimens were analyzed for the percentage area of vital bone, residual graft particles, and non‐mineralized structures (connective tissue/other non‐mineralized tissue [CT]). Changes in alveolar ridge dimensions were also determined. Results: Sixteen participants in the SPS group and 14 in the MPS group completed the study. The SPS group had a mean of 49% vital bone, 8% residual graft, and 43% CT. The MPS group had 53%, 5%, and 42%, respectively. Patients in both groups lost a mean of <1 mm alveolar height on the buccal and lingual aspects and <1.5 mm of total ridge width. There were no statistically significant differences between the two groups for any clinical or histologic parameters. Conclusion: The results of this study suggest that addition of larger bone particles to DBM putty does not offer additional benefit in the preservation of alveolar bone after the extraction of molar teeth.     

根向复位瓣技术重建种植牙颊侧角化龈的临床探讨

目的 探讨在口腔种植修复中应用根向复位瓣技术重建颊侧角化龈的方法,评价其应用效果.方法 选择上颌后牙区单颗牙种植术后颊侧角化龈缺失或过窄的患者13例,在种植Ⅱ期手术时同期行根向复位瓣术进行角化龈重建,术后1个月取模行冠修复.测量并比较术前、冠修复后1个月、6个月、12个月术区转移角化组织的宽度及厚度,记录牙龈指数(gingival index,GI)和龈沟探诊出血(bleeding on probing,BOP)情况.结果 冠修复后1、6、12个月,转移组织角化特征明显,组织健康,质地色泽与邻牙一致.3次测量宽度均值分别(3.25±0.40)mm、(3.04±0.34)mm、(2.97±0.32)mm;厚度均值分别为(2.05±0.20)mm、(1.91±0.23)mm、(1.84±0.25)mm;与邻牙角化龈的宽度(3.19±0.42)mm和厚度(1.96±0.23)mm的差异无统计学意义(P>0.05).GI和BOP阳性率与邻牙接近,呈健康牙龈形态.结论 在种植Ⅱ期手术时同期采用根向复位瓣技术能有效重建种植体周围的附着龈,效果可靠.     

Bone morphology after delayed tooth replantation – case series

The purpose of this report was to describe the morphological changes in the alveolar bone after delayed replantation of avulsed teeth using three dimensional cone‐beam computed tomography in 11 during the time period 2003–2012. The radiographic observations revealed the following: Delayed replantation results in ankylosis‐related replacement root resorption; the resorption is delayed or arrested around the cervical area superior to the alveolar crest. The buccal bone is reduced in thickness but not the palatal bone. The buccal bone resorption of the alveolar crest progresses approximately to the root canal space of the ankylosed root. Delayed replantation does not completely maintain the bone volume. The buccal profile of alveolar bone in the maxillary anterior region is depending on teeth with viable periodontal ligament.     

Microcomputed Tomographic Analysis of the Alveolar Ridge Alteration around Extraction Sites with and without Immediate Implants Placement: In Vivo Study

Background: The aim was to assess the alveolar ridge alteration around extraction sites with and without immediate implants according to extraction socket classification (ESC) using microcomputed tomography (micro‐CT). Material and Methods: Ten beagle dogs (mean age and weight: 24 ± 0.83 months and 13.8 ± 0.49 kg, respectively) were randomly divided into three groups according to the ESC. In Group 1 (ESC‐I), bilateral first and third premolars were extracted and replaced with immediate implants. In Group 2 (ESC‐II), two adjacent premolars were extracted with one immediate implant placement in the mesial socket in the maxilla and in the distal socket in the mandible. In Group 3 (ESC‐III), three adjacent teeth were extracted and an immediate implant was placed in the central socket. Primary closure was achieved using resorbable sutures. Buccal sites with dehiscence defects were excluded. After 4 months, subjects were sacrificed and alveolar ridge widths were measured at 1 mm interval in axial and sagittal views, using micro‐CT in sites with and without immediate implants. Results: In sites without immediate implant placement, alveolar ridge width was significantly higher in Group 1(6.1 ± 1.35 mm) than Group 3 (4.14 ± 1.53 mm) (p < .05). In sites with immediate implant placement, the alveolar ridge width was higher among sites in Group 1 (6.4 ± 3.8 mm) than Group 2 (4.8 ± 0.46 mm) (p < .05) and Group 3 (5.02 ± 0.84 mm) (p < .05). Overall, between each corresponding group in both sites with and without immediate implant placement at 1 mm thickness, there was no significant difference in the alveolar ridge widths. Conclusion: With the exception of Group 1 (ESC‐I), immediate implant placement did not prevent or minimize bone remodeling in extraction sites according to ESC.     

Evaluation of alveolar process resorption after tooth extraction using the socket shield technique without immediate installation of implants: a randomised controlled clinical trial

Our aim was to evaluate resorption of the alveolar ridge using the socket shield technique (SST) without immediate placement of dental implants. This randomised controlled clinical trial included 27 patients: 14 maxillary non-molar teeth were partially extracted using the SST (test group) and 13 were extracted using a minimally traumatic extraction approach (control group). Alterations in height and thickness of the alveolar ridge were evaluated by cone beam computed tomograms taken immediately after, and 100 days after, surgery. Minor resorption was observed in the height of the buccal and palatal plates, without intergroup difference (p ≥ 0.10). The test group showed significantly better preservation of the buccal-to-palatal crest dimension (p ≤ 0.05). In the control group, preservation of buccal plate thickness was significantly greater (p ≤ 0.05), but intragroup vertical resorption of the buccal plate and reduction in the buccal-to-palatal crest distance were greater (p ≤ 0.05). The SST without the immediate placement of implants showed greater preservation of the buccal-to-palatal crest dimension and lower preservation of buccal wall thickness compared with minimally traumatic extraction. In addition, it provided superior maintenance of the baseline buccal wall height. The modified SST is a promising approach, but factors that interfere with the results should be investigated.     

Ridge preservation using a composite bone graft and a bioabsorbable membrane with and without primary wound closure: a comparative clinical trial

Background: The aim of this single‐masked, randomized controlled clinical trial is to compare hard and soft tissue changes after ridge preservation performed with (control, RPc) and without (test, RPe) primary soft tissue closure in a split‐mouth design. Methods: Eleven patients completed this 6‐month trial. Extraction and ridge preservation were performed using a composite bone graft of inorganic bovine‐derived hydroxyapatite matrix and cell binding peptide P‐15 (ABM/P‐15), demineralized freeze‐dried bone allograft, and a copolymer bioabsorbable membrane. Primary wound closure was achieved on the control sites (RPc), whereas test sites (RPe) left the membrane exposed. Pocket probing depth on adjacent teeth, repositioning of the mucogingival junction, bone width, bone fill, and postoperative discomfort were assessed. Bone cores were obtained for histological examination. Results: Intragroup analyses for both groups demonstrated statistically significant mean reductions in probing depth (RPc: 0.42 mm, P = 0.012; RPe: 0.25 mm, P = 0.012) and bone width (RPc: 3 mm, P = 0.002; RPe: 3.42 mm, P <0.001). However, intergroup analysis did not find these parameters to be statistically different at 6 months. The test group showed statistically significant mean change in bone fill (7.21 mm; P <0.001). Compared to the control group, the test group showed statistically significant lower mean postoperative discomfort (RPc 4 versus RPe 2; P = 0.002). Histomorphometric analysis showed presence of 0% to 40% of ABM/P‐15 and 5% to 20% of new bone formation in both groups. Comparison of clinical variables between the two groups at 6 months revealed that the mucogingival junction was statistically significantly more coronally displaced in the control group than in the test group, with a mean of 3.83 mm versus 1.21 mm (P = 0.002). Conclusions: Ridge preservation without flap advancement preserves more keratinized tissue and has less postoperative discomfort and swelling. Although ridge preservation is performed with either method, ≈27% to 30% of bone width is lost.     

Radiographic alveolar bone changes following ridge preservation with two different biomaterials

Objectives: The aim of this randomized controlled trial was to evaluate radiographical bone changes following alveolar ridge preservation with a synthetic bone substitute or a bovine xenograft. Methods: Alveolar ridge preservation was performed in 27 patients randomized in two groups. In the test group (n=14), the extraction socket was treated with Straumann bone ceramic^® (SBC) and a collagen barrier membrane (Bio‐Gide^®), whereas in the control group (n=13) with deproteinized bovine bone mineral and the same barrier. Standardized periapical X‐rays were taken at 4 time points, BL: after tooth extraction, GR: immediately after socket grafting, 4M: 16 weeks, 8M: 32 weeks post‐operatively. The levels of the alveolar bone crest at the mesial (Mh), and distal (Dh) and central aspects of the socket were measured at all time points. All the radiographs obtained were subtracted from the follow‐up images. The gain, loss and unchanged areas in terms of grey values were tested for significant difference between the two groups. Results: In the test group, the Mh and Dh showed a mean difference (± standard deviation) of 0.9 ± 1.2 and 0.7 ± 1.8 mm, respectively, among BL‐8M. In the control group, the Mh and Dh showed a mean difference of 0.4 ± 1.3 and 0.7 ± 1.3 mm, respectively (P>0.05). Both treatments presented similar gain in grey values between BL‐GR, BL‐4M and BL‐8M. The SBC presented less loss in grey values between BL‐4M and BL‐8M (P<0.05). Radiographic assessment underestimated the intrasurgical measurements (mesial and distal) of an average 0.3 mm (95% CI, 0.02–0.6). Conclusion: Both types of bone grafts presented similar radiographic alveolar bone changes when used for alveolar ridge preservation. To cite this article:
Mardas N, D'Aiuto F, Mezzomo L, Arzoumanidi M, Donos N. Radiographic alveolar bone changes following ridge preservation with two different biomaterials.
Clin. Oral Impl. Res. 22 , 2011; 416–423.     

Histologic Evaluation of Wound Healing After Ridge Preservation With Cortical,Cancellous, and Combined Cortico‐Cancellous Freeze‐Dried Bone Allograft: A Randomized Controlled Clinical Trial

Background: Cortical and cancellous mineralized freeze‐dried bone allografts (FDBA) are available for use in alveolar ridge preservation after tooth extraction. There are currently no data regarding use of a combination 50%/50% cortico‐cancellous FDBA compared with a 100% cortical or 100% cancellous FDBA in ridge preservation. The primary objective of this study is to dimensionally and histologically evaluate healing after ridge preservation in non‐molar sites using 50%/50% cortico‐cancellous FDBA versus 100% cortical and 100% cancellous FDBA. Methods: Sixty‐six patients requiring extraction of a non‐molar tooth were enrolled and randomized into three groups to receive ridge preservation with the following: 1) 100% cortical FDBA; 2) 100% cancellous FDBA; or 3) 50%/50% cortico‐cancellous FDBA. After 18 to 20 weeks of healing, a biopsy was harvested, and an implant was placed. The alveolar ridge was measured pre‐ and postoperatively to evaluate change in ridge height and width. Percentages of vital bone, residual graft, and connective tissue (CT)/other were determined via histomorphometric analysis. Results: Histomorphometric analysis revealed no significant differences among groups regarding percentage of vital bone or CT/other. The 100% cortical FDBA group had significantly greater residual graft material (P = 0.04). Dimensional analysis revealed no significant between‐group differences in any parameter measured. Conclusion: To the best knowledge of the authors, this study offers the first histologic evidence demonstrating no significant difference in vital bone formation or dimensional changes among 50%/50% cortico‐cancellous FDBA, 100% cortical FDBA, and 100% cancellous FDBA when used in ridge preservation of non‐molar tooth sites.     

Bone healing dynamics at buccal peri-implant sites

BACKGROUND: It is common belief that immediate implant placement into extraction sites may act to preserve the alveolar process. The objective of this study was to evaluate healing dynamics at buccal peri-implant sites in relation to the dimensions of the alveolar ridge. METHODS: Bilateral, critical-size, supraalveolar, peri-implant defects were created in 12 male Hound Labrador mongrel dogs following surgical horizontal cut-down of the alveolar ridge. Each jaw quadrant received three 10-mm titanium implants placed 5 mm into extraction sites of the third and fourth premolar teeth leaving 5 mm in a supraalveolar position. The mucoperiosteal flaps were advanced, adapted, and sutured for primary intention healing. Bone fluorescent markers were administered at weeks 3 and 4 postsurgery, and pre-euthanasia. Incandescent, polarized, and fluorescent light microscopies were used to assess the width of the buccal wall of the alveolar ridge and local bone remodeling over the 8-week healing interval. RESULTS: There was a significant association between the width of the buccal alveolar ridge and extent of bone resorption evaluated by incandescent and fluorescent light microscopy. A non-linear association was observed between the buccal ridge width and resorption of the alveolar ridge. A 2-mm threshold was established to account for this non-linearity. The strength of this association was two times greater in specimens with a buccal ridge width <2 mm compared with a wider ridge (beta=1.62 vs. 0.80) observed by fluorescent light microscopy. Accordingly, mean buccal resorption was significantly greater when the ridge width was <2 mm. Fluorescent light microscopy consistently showed greater buccal resorption compared with incandescent light microscopy (P<0.05). Agreement between the examination techniques was low (concordance correlation coefficient=0.49), especially for higher values of buccal resorption. CONCLUSION: When implants are placed into extraction sites, proximity to the buccal alveolar crest appears a major consideration. The observations herein suggest that the width of the buccal alveolar ridge should be at least 2 mm to maintain the alveolar bone level. These observations likely have general implications for implant placement using most surgical protocols.