Localized ridge augmentation in dogs: a pilot study using membranes and hydroxyapatite

This study was designed to evaluate the potential to reconstruct localized ridge defects with bone by preventing non-osteogenic extraskelatal connective tissue from participating in the process of healing following experimental ridge augmentation treatment procedures. Following the elevation of buccal muco-periosteal flaps, buccal, interproximal, and interradicular bone was removed to the apical level of the second and third premolar teeth and the teeth were extracted to create bucco-lingual ridge defects that averaged 13 mm x 7 mm x 3.5 mm in each quadrant of two adult beagle dogs. The defects were permitted to heal for 90 days. The defects did not fill in with new bone. Subsequently, buccal muco-periosteal flaps were elevated and a membrane was placed over the defect and positioned so that it rested on bone that was exposed adjacent to the defect. In two quadrants test support materials were used to ensure that a space was maintained between the surface of the defect and the membrane. One quadrant was maintained as a sham-operated control site, three sites received membranes and no supporting implants and two sites received supporting implants and no membranes. The surgical schedule was designed to yield sacrifice times of 8 to 12 weeks. In the three quadrants available for study that were covered with membranes, bone and/or non-mineralized connective tissue was found to fill all of the space that had been provided by the membrane. Histologic examination confirmed that the space was filled with young, actively growing bone by 90 days. No new bone formation (bone fill) was observed in the sham-operated control site.     

Dimensional changes of the ridge contour after socket preservation and buccal overbuilding: an animal study

Objectives: The aim of the study was to volumetrically assess alterations of the ridge contour after socket preservation and buccal overbuilding.
Material and Methods: In five beagle dogs, four extraction sites were subjected to one of the following treatments:
Tx 1 : The socket was filled with BioOss Collagen^® and covered with a free gingival autograft from the palate (SP).
Tx 2 : The buccal bone plate was forced into a buccal direction using a manual bone spreader and SP was performed.
Tx 3 : The buccal bone plate was forced into a buccal direction using a manual bone spreader; SP was performed.
Tx 4 : The socket was filled with BioOss Collagen and a combined free gingival/connective tissue graft was used to cover the socket and for buccal tissue augmentation.
Impressions were obtained at baseline, 2 weeks and 4 months post-operatively. Casts were optically scanned and superimposed in one common coordinate system. Using digital image analysis, the volumetric differences per area among the different treatment time points and among the treatment groups were calculated.
Results: Four months after tooth extraction, no statistically significant differences with regard to the buccal volume per area could be assessed among the treatment groups.
Conclusion: Overbuilding the buccal aspect in combination with socket preservation is not a suitable technique to compensate for the alterations after tooth extraction.     

Dimensional changes of the alveolar ridge contour after different socket preservation techniques

Objectives: The aim of the following study was to assess contour changes after socket preservation techniques. Material and Methods: In five beagle dogs, the distal root of the third and fourth mandibular premolars was extracted. The following treatments (Tx) were randomly assigned for the extraction socket. Tx 1: BioOss Collagen. Tx 2: BioOss Collagen and a free soft tissue graft. Tx 3: No treatment. Tx 4: The internal buccal aspect was covered with an experimental collagen membrane, the extraction socket was filled with BioOss Collagen and the membrane folded on top of the graft. Impressions were obtained at baseline, 2 and 4 months after surgery. Bucco‐lingual measurements were performed using digital imaging analysis. Results: All groups displayed contour shrinkage at the buccal aspect. Only the differences between the two test groups (Tx 1, Tx 2) and the control group (Tx 3) were significant at the buccal aspect (p0.001). No measurements of the Tx 4 group could be performed. Conclusion: Socket preservation techniques, used in the present experiment, were not able to entirely compensate for the alterations after tooth extraction. Yet, incorporation of BioOss Collagen seems to have the potential to limit but not avoid the post‐operative contour shrinkage.     

Dimensional ridge alterations following tooth extraction. An experimental study in the dog

OBJECTIVE: To study dimensional alterations of the alveolar ridge that occurred following tooth extraction as well as processes of bone modelling and remodelling associated with such change. MATERIAL AND METHODS: Twelve mongrel dogs were included in the study. In both quadrants of the mandible incisions were made in the crevice region of the 3rd and 4th premolars. Minute buccal and lingual full thickness flaps were elevated. The four premolars were hemi-sected. The distal roots were removed. The extraction sites were covered with the mobilized gingival tissue. The extractions of the roots and the sacrifice of the dogs were staggered in such a manner that all dogs contributed with sockets representing 1, 2, 4 and 8 weeks of healing. The animals were sacrificed and tissue blocks containing the extraction socket were dissected, decalcified in EDTA, embedded in paraffin and cut in the buccal-lingual plane. The sections were stained in haematoxyline-eosine and examined in the microscope. RESULTS: It was demonstrated that marked dimensional alterations occurred during the first 8 weeks following the extraction of mandibular premolars. Thus, in this interval there was a marked osteoclastic activity resulting in resorption of the crestal region of both the buccal and the lingual bone wall. The reduction of the height of the walls was more pronounced at the buccal than at the lingual aspect of the extraction socket. The height reduction was accompanied by a "horizontal" bone loss that was caused by osteoclasts present in lacunae on the surface of both the buccal and the lingual bone wall. CONCLUSIONS: The resorption of the buccal/lingual walls of the extraction site occurred in two overlapping phases. During phase 1, the bundle bone was resorbed and replaced with woven bone. Since the crest of the buccal bone wall was comprised solely of bundle this modelling resulted in substantial vertical reduction of the buccal crest. Phase 2 included resorption that occurred from the outer surfaces of both bone walls. The reason for this additional bone loss is presently not understood.     

Dimensional ridge alterations following immediate implant placement in molar extraction sites: a six-month prospective cohort study with surgical re-entry

Aim: To assess dimensional ridge alterations following immediate implant placement in molar extraction sites.
Material and methods: Twelve subjects received 12 immediate transmucosal implants in molar extraction sites. Peri-implant defects were treated according to the principles of Guided Bone Regeneration by means of a deproteinized bone substitute and a bioresorbable collagen membrane. Changes in vertical (IS-BD, CREST-BD) and horizontal distances (EC-I, IC-I) of alveolar bony walls to the bottom of the defects (BD) and to the implant surfaces (I) were compared between implant placement and surgical re-entry at 6 months.
Results: The implant survival rate at 6 months was 100%. Statistically significant differences ( P <0.01) were observed in the mean changes in vertical distances IS-BD and CREST-BD between baseline and re-entry. At re-entry, all peri-implant marginal defects assessed from the internal socket wall to the implant surface (IC-I) were healed. The residual combined thickness of the buccal wall with the newly formed peri-implant bone at sites with an initial thickness of 1 mm was statistically significantly smaller ( P <0.05) compared with that of sites with an initial buccal thickness of 2 mm (2.50 ± 0.76 vs. 4±0 mm).
Conclusions: The marginal defects around immediate implants placed in molar extraction sites were completely filled after 6 months of healing through de novo bone formation. Bone resorption was observed from the external aspects of the buccal and oral socket walls. Dimensional changes of the external socket walls were mostly pronounced at the buccal aspects.     

珊瑚骨粉复合组织补片进行拔牙位点保存的临床研究

目的探讨使用珊瑚骨粉复合组织补片进行拔牙位点保存的临床效果。方法选取自2012年12月至2014年2月期间在武警总医院口腔种植科门诊采用微创技术拔除磨牙的患者45例,试验组20例,拔牙窝内植入珊瑚骨粉,组织补片覆盖表面关闭拔牙窝;对照组25例,拔牙后常规处理。1、3、6个月复诊,观察拔牙窝愈合情况。拔牙前及拔牙6个月后进行口内取模灌注石膏模型并拍摄X线牙片,分别测量牙槽嵴的高度和宽度,使用配对t检验分别对两组拔牙前至6个月期间牙槽嵴高度、宽度的变化进行统计学分析,使用两独立样本的t检验进行两组间牙槽嵴高度、宽度变化的比较,P〈0.05为差异具有统计学意义。结果临床观察除有一例组织补片脱落外,试验组其他拔牙窝均愈合良好,牙槽骨丰满,牙龈色、形、质与邻牙协调;而对照组牙槽嵴吸收、萎缩,高度降低、宽度显著缩小。统计学分析试验组牙槽嵴高度和宽度的改变无显著的统计学差异（P〉0.05）;对照组的上述改变具有统计学差异（P〈0.05）。两组间牙槽嵴高度、宽度的变化相比,二者间的差异均具有统计学意义（P〈0.05）。结论珊瑚骨粉复合组织补片有效保存了进行种植牙修复所必需的骨量,是进行拔牙后位点保存术的合适材料。     

Hard tissue alterations after socket preservation: an experimental study in the beagle dog

Objectives: The aim of the following experimental study was to assess bone changes in the horizontal and vertical dimension when using different socket preservation procedures. Material and methods: In five beagle dogs the distal roots of the 3rd and 4th premolar were extracted without elevation of a mucoperiosteal flap and the following treatments were assigned: Tx 1: The extraction socket was filled with BioOss Collagen^® (Geistlich Biomaterials, Wolhusen, Switzerland) and interrupted sutures were applied.: Tx 2: The extraction socket was filled with BioOss Collagen^® (Geistlich Biomaterials, Wolhusen, Switzerland) and a free gingival graft was sutured to cover the socket.: Tx 3: The extraction socket was left with its blood clot and interrupted sututes were applied.: Four month after surgery the dogs were sacrificed and from each extraction site two histological sections were selected for histometric analysis. The following parameters were evaluated: (1) the vertical dimension was determined by placing a horizontal line on the lingual bone wall. Then, the distance from this line to the buccal bone wall was measured. (2) The horizontal dimension was assessed at three different areas measured from the top of the lingual crest: 1 mm (Value 1), 3 mm (Value 3) and 5 mm (Value 5). Results: The mean vertical loss of the buccal bone plate for the Tx 1 group was 2.8±0.2 mm. The Tx 2 group showed vertical loss of 3.3±0.2 mm. The Tx 3 group demonstrated 3.2±0.2 mm of mean vertical loss. The horizontal dimension of the alveolar process was 4.4±0.3/6.1±0.2/7.2±0.1 mm at the three different levels for the Tx 1 group. The Tx 2 group depicted bone dimensions of 4.8±0.2/6.0±0.2/7.1±0.1 mm. The horizontal dimension of the Tx 3 group was 3.7±0.3/6.2±0.2/7.0±0.1 mm. When the results from the horizontal measurements were tested with the analysis of variance (anova ), a clear significance could be found in particular for Value 1 mm between the test groups Tx 1 and Tx 2 and the control group (Tx 3) (P<0.001). Furthermore the mean of treatment 1 (Tx 1) was slightly significantly lower than of treatment 2 (Tx 2) (P<0.05). Conclusion: The findings from the present study disclose that incorporation of BioOss Collagen^® into the extraction socket has only limited impact on the subsequent biologic process with particular respect to the buccal bone plate. The horizontal measurement of the alveolar ridge depicted that the loss of the buccal bone plate was replaced to a certain amount by newly generated bone guided by the BioOss Collagen^® scaffold. It seems that the mechanical stability provided by BioOss Collagen^® and furthermore by a free gingival graft could act as a placeholder preventing the soft tissue from collapsing.     

Measurement of ridge alterations following tooth removal: a radiographic study in humans

Objective: The aim of this study was a radiographic mesiodistal analysis of the shape of the bone crest 3 months after tooth removal. Material and methods: One hundred single tooth extractions were performed on 100 patients because of orthodontic or prosthetic causes. Bite blocks were used for two radiographs: one on the day of extraction and the other after healing of the socket, 3 months later. These X‐rays were used to determine: (1) the most apical distance of alveolar ridge resorption, with baseline as the line between bone‐to‐teeth contact (the greatest distance in bone resorption height) and (2) the mesiodistal distance (MDD) and mesial and distal angles arising after bone tissue modeling. Results: Significant differences (P<0.05) emerged between the MDDs of multiple‐ [8 mm, 95% confidence interval (CI): 6.09, 9.90] and single‐root teeth (5.60 mm, 95% CI: 4.80, 6.50). However, mesial or distal angles or the most apical distance of alveolar ridge resorption did not differ (mean distance in height=4.32 mm, 95% CI: 3.85, 4.78; mean angle=24°). Conclusions: In this study, the post‐extraction mesiodistal bone distance between teeth adjacent to the edentulous ridge depends on the size of the edentulous space. Nevertheless, the distance does not affect the distance in bone loss height. The distance of bone resorption height reaches a balance at the midpoint, which we consider indicative of stable healing. This resorption process must be considered when placing dental implants in fresh extraction sockets, especially in aesthetic sites, because the implant surfaces could be exposed after 3 months. To cite this article:
Moya‐Villaescusa MJ, Sánchez‐Pérez A. Measurement of ridge alterations following tooth removal: a radiographic study in humans.
Clin. Oral Impl. Res. 21 , 2010; 237–242.
doi: 10.1111/j.1600‐0501.2009.01831.x     

Hard tissue alterations after socket preservation with additional buccal overbuilding: a study in the beagle dog

Objectives: The aim of this study was to histometrically assess alterations of the ridge following socket preservation alone and socket preservation with additional buccal overbuilding.
Material and Methods: In five beagle dogs four extraction sites were randomly subjected to one of the following treatments:
Tx 1: The socket was filled with BioOss Collagen^® and covered with a free gingival graft from the palate.
Tx 2: The buccal bone plate was augmented using the GBR-technique, the socket was filled with BioOss Collagen^® and covered with a free gingival graft.
Tx 3: The buccal bone plate was forced into a buccal direction using a manual bone spreader. The socket was filled with BioOss Collagen^® and covered with a free gingival graft from the palate.
Tx 4: The socket was filled with BioOss Collagen^® and a combined free gingival/connective tissue graft was used to cover the socket and for buccal tissue augmentation.
For each experimental site, two histological sections were subjected to histometric analysis and evaluated for (i) vertical bone dimensions and (ii) horizontal bone dimensions.
Results: All treatment groups showed horizontal and vertical bone loss. The mean vertical bone loss of the buccal bone plate was significantly lower in Tx 4 than in the other groups, while no statistical significant differences could be detected among the groups in the horizontal dimension.
Conclusion: Overbuilding the buccal aspect in combination with socket preservation does not seem to be a suitable technique to compensate for the alterations after tooth extraction.     

生物膜在位点保护中的应用

由于拔牙后持续渐进的骨吸收,牙槽骨在高度和宽度上会有一定损失,从而影响种植体的植入和骨整合,同时也导致美学效果欠佳.而位点保护是在拔牙窝填塞骨替代材料来防止和减少骨流失的方式.但骨粉在拔牙窝直接填塞容易漏出,常需关闭创口.关闭拔牙创的方法包括采用游离牙龈组织(金标准)和转瓣手术,但游离牙龈以及转瓣需取患者自体牙龈,造成二次创伤.而利用胶原膜、致密聚四氟乙烯(dPTFE)膜等不同人工材料关闭创口可减少患者的不适,但在位点保护中是否采用生物膜仍存有争议.因此笔者综述位点保护中使用生物膜,以及其他不使用生物膜的方法,以期为临床操作提供参考.     

Clinical effects of nanocrystalline hydroxyapatite paste in the treatment of intrabony periodontal defects: a randomized controlled clinical study

The purpose of the present randomized controlled clinical study was to compare the clinical outcomes of papilla preservation flap surgery with or without the application of a novel nanocrystalline hydroxyapatite (nano-HA) bone graft substitute. Fourteen patients with paired intrabony periodontal defects of ≥4 mm participated in this split-mouth design study. The defects in each subject were randomly selected to receive nano-HA paste in conjunction with papilla preservation flaps or papilla preservation flaps alone. Probing bone levels (PBL) from a customized acrylic stent and probing pocket depths (PPD) were measured at baseline and again 6 months following surgery. No differences in any of the investigated parameters were observed at baseline between the two groups. Healing was uneventful in all patients. Both treatments resulted in significant improvements between baseline and 6 months (p < 0.05). At 6 months after therapy, the sites treated with nano-HA paste showed a reduction in mean PPD from 8.3 ± 1.2 to 4.0 ± 1.1 mm and a gain in PBL of 4.3 ± 1.4 mm, whereas in the control group, the mean PPD changed from 7.9 ± 1.2 mm to 5.0 ± 1.2 mm and PBL gain was 2.6 ± 1.4 mm. Results demonstrated statistically greater PPD reduction and PBL gain (p < 0.05) in the test group as compared with the control group. In conclusion, after 6 months, the treatment of intrabony periodontal defects with a nano-HA paste leads to significantly improved clinical outcomes when compared with papilla preservation flap surgery alone.     

Bio-oss和Bio-oss骨胶原保持牙槽骨量的临床研究

目的观察Bio-oss及Bio-oss骨胶原填充于拔牙后新鲜牙槽窝对于早期牙槽嵴形态改建的影响。方法24枚上、下颌后牙拔除后同时给予不同处理,其中拔牙窝填充混合富血小板血浆的Bio-oss(BP组)7例;拔牙窝填充Bio-oss骨胶原(BC组)7例;拔牙窝自然愈合(C组)10例。牙齿拔除后1～2周、9～12周两次复诊,观察牙龈愈合差异,取模型,测量缺牙处牙槽嵴宽度,行不同组间及组内的前后比较。结果各组牙槽嵴宽度前后模型测量存在差异(P<0.05);BP组与BC组,BP组与C组间前后差值存在显著差异(P<0.05)。结论Bio-oss植入减轻了拔牙后牙槽嵴的吸收,Bio-oss骨胶原对于拔牙窝嵴顶处牙龈上皮的爬行覆盖具有促进作用。     

Postextraction ridge preservation using a synthetic alloplast

Ridge preservation is the prevention of the 40% to 60% jaw-bone atrophy that normally takes place 2 to 3 years postextraction and continues at a rate of 0.25% to 0.5% per year until death. It is achieved by the immediate grafting of the extraction socket with or without the use of an immediate implant. It offers the dentist the ability to preserve the alveolar ridge for future implant and restorative dentistry, to achieve anterior esthetics, and to prevent postoperative pain and bleeding. The practice of ridge preservation involves advanced extraction therapy and replacement therapy.