再植牙复合牙周膜细胞的实验研究

目的:研究体外培养的牙周膜细胞与牙根共同再植入人造牙槽窝内,其组织形成的能力与促进牙周再生的潜能。方法:拔除2只杂种狗的第三、第四前磨牙,得到牙周膜细胞并进行体外培养。拔牙后1个月,将体外培养的牙周膜细胞与自体牙根共同再植入右侧下颌无牙区的人造牙槽窝内,左侧下颌作为对照。再植2个月后,处死动物,标本制成石蜡切片,HE染色,光镜下进行组织学观察。结果:实验组标本中,在与近根尖部分牙根相对的一些区域可以看到垂直于骨表面的纤维束包埋于牙槽窝壁中。结论:即使被植入人造牙槽窝中,体外培养的牙周膜细胞仍保留了在体内形成类牙周膜组织的能力。     

The use of Periograf in periodontal defects. Histologic findings

Hydroxylapatite (Periograf) was placed into periodontal defects around five teeth scheduled for extraction in two young adult females with excellent plaque control. On the facial surface for one tooth the material was placed in a supracrestal position. Twelve months later the teeth were extracted in block section and were examined microscopically. Hydroxylapatite crystals were seen in the histologic sections with evidence of new bone formation in juxtaposition. The hydroxylapatite was tolerated relatively well by the surrounding tissue. A "cap' of bone was present coronal and facial to those crystals placed in the supracrestal position. In some areas bone was seen attached to the root via a periodontal ligament coronal to the Durapatite crystals. The question of accidental implantation of the material into the adjacent bone versus the actual regeneration of a true new attachment was discussed.     

Periodontal healing by periodontal ligament cell sheets in a teeth replantation model

ObjectiveSuccessful transplantation of avulsed teeth is to restore the attachment and regenerate the periodontal support. Different strategies have been applied in treatment from modification of teeth storage, antibiotic usage to peridontium tissue replacement. We developed a novel periodontal ligament cell-sheet delivery system to apply on delayed replanted teeth in promoting periodontal healing in a canine model.DesignAutologous periodontal ligament (PDL) fibroblasts were isolated from extracted premolars of beagle dog. The cell-sheets were fabricated using normal culture dish after stimulation of extracellular matrix formation. Teeth were surgically extracted and attached soft tissues were removed. After root canal treatment, the root of teeth were wrapped by the PDL cell-sheets and replanted back to prior socket accordingly whilst teeth without cell sheets as a control. Eight weeks after surgery, the animals were sacrificed and decalcified specimens were prepared. Regeneration of periodontal tissue was evaluated through histology assay.ResultsMulti-layered PDL cell-sheet could be attached on tooth root and most cells on sheet-tooth constructs were viable before replantation. Minimum clinical signs of inflammation were observed in experiment. PDL cell-sheets group show significant higher occurrence of favourable healing (88.4%) than control group with low healing (5.3%). Periodontal ligament and cememtum tissue regeneration was observed in the experimental group, and the regenerated tissues showed high collagen type III, type I and fibronectin expression.ConclusionThe periodontal ligament cell-sheets fabricated through normal cell culture dish has a potential for regeneration of periodontal ligament and may become a novel therapy for avulsed teeth replantation.     

骨髓基质细胞-牙根-珊瑚羟基磷灰石复合体体内再植的初步观察

目的:评价体外构建的骨髓基质细胞(BMSCs)、珊瑚-羟磷灰石支架(CHA)、牙根复合体植入体内后牙根周组织的再生情况。方法:体外分离纯化的狗BMSCs分别与牙根及CHA支架共培养形成复合体后植入体内生长,16周后取材,组织切片观察牙根周组织的再生情况。结果:实验组较对照组所不同的是:有更趋成熟、致密的牙槽骨生成;牙根与牙槽骨之间形成了清晰的软组织间隙———类牙周膜结构,主要由纤维组织、毛细血管组成。结论:BMSC-CHA-牙根复合物植入体内后有效促进牙周组织的再生;组织工程学方法促进牙周组织再生具有可行性。     

Remodelling of periodontal ligament in erupting molars of mature rats

A wound was made 2 mm apical to the alveolar bone crest in the left mandible of 6 rats. The wound extended from the mesial of the first molar to the distal of the third molar, and penetrated alveolar process, periodonlal ligament and into the roots of the teeth. The opposing maxillary molars were extracted, and the mandibular molars were allowed to erupt for 2. 4 or 5 days. Histological sections cut in the coronal plane through the wounds showed that the teeth had erupted, particularly after the longer time periods. It was evident that fibres of the periodontal ligament attached to cementum had been carried into the apical part of the wound. No fibres were found attached to the alveolar bone immediately coronal to the wound. Few organized bundles were seen to be attached to alveolar bone elsewhere in the ligament of erupting teeth. These results were interpreted as not lending support to the view that remodelling of the periodontal ligament in a mature tooth of limited eruption occurs in an "intermediate plexus". Rather, they are thought to suggest that remodelling in a mature tooth in which eruption has been reactivated occurs predominantly in the peripheral part of the ligament.     

In vitro proliferation of periodontal ligament-like tissue on extracted teeth

ObjectiveTransplantation of autologous teeth is a routine component of orthodontic treatment. The aim of this study was to develop a method for the regeneration of damaged periodontal ligament (PDL) on extracted teeth using a three-dimensional culture system.DesignWe used the maxillary first premolars or third molars extracted from patients for orthodontic treatment. The extracted teeth were stained with toluidine blue to measure the residual PDL area. After confirming damage of the periodontal tissue on the root surface of the extracted teeth, we tried to regenerate the periodontal tissue. Other extracted teeth were inserted into a cell strainer filled with cellulose-based carrier materials to regenerate the periodontal tissue. The strainer was then placed in a 90-mm culture dish filled with culture medium and incubated at 37 °C and 5% CO2 for about 1 month. The cultured teeth were observed under a stereomicroscope and examined by scanning electron microscopy (SEM), and were stained to detect alkaline phosphatase (ALP) activity.ResultToluidine blue staining revealed that the residual periodontal membrane covered an average of 50.4% of the root surface area of each tooth. After culturing extracted teeth with our culture system, globular structures were found on the entire tooth root surface by stereomicroscopy, and PDL-like filamentous tissue was also detected by SEM. The entire tooth root surfaces of the cultured teeth were positive for ALP activity.ConclusionsWe have developed a useful culture method to stimulate the proliferation of cells in PDL-like tissue on the roots of extracted teeth.     

Tooth auto-transplantation with double periodontal ligament stimulation to replace periodontally compromised teeth

BACKGROUND: The healing process of autotransplantation puts 2 different tissues in competition: the ligament on the root surface and the bone tissue of the alveolus. This study shows the effects of a protocol with 2 surgical stages, which promote ligament repair, inhibit adhesion between bone and dental root, and reduce the occurrence of the ankylosis-root resorption phenomenon. METHODS: Forty-three patients, 33 to 73 years old, received 47 transplantations of mature teeth (including retained teeth) during a 5-year period. During the first surgical step, the transplanted tooth is extracted, measured, immediately replaced in its origin site, and maintained with an original suture technique. The alveolus to which the tooth will be transplanted is adapted after extraction of the periodontally compromised tooth. The second surgery occurs at day 14, when regeneration of periodontal ligament (PDL) is at a maximum (first stimulation). The tooth is transplanted in its new alveolus and retained using the same suture technique to avoid a rigid splint and to create mechanical stimulation of the PDL (second stimulation). RESULTS: The results were 95.75% positive with normal PDL, with a 4.25% failure rate (transplant loss) and no ankylosis. Mean probing reduction was 8.37 +/- 3.0 mm. Mean radiographic bone gain was 7.73 +/- 4.32 mm. CONCLUSIONS: This study suggests that auto-transplantation with double PDL stimulation can be a viable treatment in clinical practice, especially to replace teeth with large periodontal lesions, deep furcation defects, and/or root fractures. This study shows the high potential of stimulated PDL to regenerate alveolar bone and periodontal structures in severe destruction sites.     

Formation of a periodontal ligament around titanium implants

The aim of this study was to examine wound healing events around titanium implants in the presence of retained root tips whose periodontium could serve as a source for cells which could participate in the healing process. Hollow cylinder implants with a titanium plasma-sprayed surface were placed in the mandible of monkeys where the apical portions of previously removed teeth were retained. After a healing period of 12 months, free of functional loading, the implants with surrounding tissues were removed and specimens analyzed in undecalcified sections. This report describes histologic findings of six such implants. Microscopic analysis revealed that in regions where implants were close to retained roots, a periodontal ligament had formed around large portions of the implant. Furthermore, there was a distinct layer of cementum on the implant surface and a periodontal ligament with collagen fibers perpendicularly oriented to the implant surface, implanted into the cementum on the implant surface as well as to the opposing bone. This initial observation suggests that it may be possible to achieve an anchorage of certain dental implants with a periodontium simulating that found surrounding the normal tooth. Furthermore, these findings provide the basis for further studies on regeneration of all components of the periodontal attachment apparatus including cementum, periodontal ligament, and bone.     

再生的牙周组织在正畸压应力下破骨相关因子表达的研究

目的 研究应用改良的双相磷酸钙(biaphasic calcium phosphate,BCP)复合骨髓间充质干细胞(bone marrow mesenchymal stem cells,BMSCs)行犬牙周组织再生后,对再生的牙周组织施加正畸压应力,比较与健康牙周组织受力后破骨相关因子表达的异同,从而探讨牙周再生后进行正畸牙移动的可行性。方法 取6只成年雄性比格犬,拔除其双侧上下颌第一前磨牙,随机分为1周组、2周组和4周组,每组2只犬,实验组于每只犬右上、左下象限第二前磨牙牙根的近中侧制造牙周缺损,并将体外培养的犬BMSCs与BCP的共培物植入缺损区,牙周再生20周后施加正畸力,以1.47 N左右的力值拉第二前磨牙向近中方向移动;以自身为对照,另两象限交替作为牙周再生术后加力0周组和空白对照组。分别于加力1周、2周及4周后处死2只比格犬并取组织块。通过Real-Time PCR及Western-Blot印迹法检测破骨相关因子活化T细胞转化因子-1（NFATc-1）和组织蛋白酶K（Cath-K）的表达。结果 实验组NFATc-1和Cath-K的mRNA和蛋白表达趋势一致:从0周到2周呈上升趋势,2周至4周下降,但仍高于0周时;实验组与对照组阳性表达情况无明显差异（P>0.05)。结论 再生的牙周组织中破骨细胞相关因子的表达情况及变化趋势与正常牙周组织相似,应用改良的BCP用于牙周组织缺损的再生及再生后的正畸牙移动是可行的。     

下颌骨牵引成骨区即刻牙移动的实验研究

目的：研究下颌骨牵引成骨后在新骨区即刻牙移动时牙周组织的改建行为及牙移动规律。方法：选择4只牙列完整的Beagle犬,其中2只犬建立双侧下颌骨牵引成骨动物模型,牵引完成后,即刻以30g力远中移动下颌第三前磨牙进入牵引成骨区;另外2只犬拔除双侧下颌第四前磨牙后3个月,以30g力远中移动下颌第三前磨牙。实验中,每周加力1次拍摄X线片,并记录牙移动速率。牙移动8周后,观察实验牙及其牙周组织特点。测量数据采用SPSS12.0软件包进行t检验。结果：实验牙借助自制的持续加力装置移动进入牵引成骨区,实验牙未产生倾斜,牙无明显松动,牙根未见明显吸收。实验组牙移动速度显著快于对照组,P〈0.01。组组织学观察发现,牙槽骨和牙周膜未出现不可逆性损伤。结论：牵引成骨区的新生骨质中,牙可以快速而平稳地移动。     

Histologic evaluation of an allogeneic mineralized bone matrix in the treatment of periodontal osseous defects

The aim of this study was to evaluate the potential of an allogeneic bone matrix to regenerate new bone, cementum, and periodontal ligament around a previously diseased root surface. Four patients with severe chronic periodontitis and teeth with hopeless periodontal or restorative prognoses participated in this study. One tooth with a severe intraosseous defect was selected per patient. At baseline, measurements of probing depth, gingival recession, and clinical attachment level were obtained. Following flap reflection, a root notch was placed at the apical extent of the calculus; the root was debrided, and the allogeneic bone graft material was placed into the defect. After a minimum of 6 months of healing, the teeth were removed en bloc and prepared for histologic examination. Two of four teeth demonstrated regeneration of new bone, cementum, and periodontal ligament. One tooth healed by new connective tissue attachment, and another by junctional epthelium.     

Collagen implants do not preserve periodontal ligament homeostasis in periodontal wounds

An improved understanding of the differentiation of periodontal ligament cells could facilitate the development of new treatment approaches for overcoming the loss of specialized cell types caused by periodontitis. To study healing of wounded periodontal tissues and the differentiation of mineralizing connective tissue cells in periodontal ligament, we have examined the influence of wound size and collagen implantation on the regeneration of periodontium and on immunohistochemical staining for osteopontin and bone sialoprotein. Four groups of Wistar rats were wounded by drilling through the alveolar bone and by extirpation of the periodontal ligament. Wounds were 0.6 or 1.8 mm in diameter and defects were either implanted with collagen gels or were treated without implants. Rats were killed at 1 wk or 2 months after wounding and tissue sections were stained with monoclonal antibodies against rat osteopontin and bone sialoprotein. Collagen implants strongly increased staining for osteopontin and bone sialoprotein in defects at 1 wk. By 2 months alveolar bone healed completely regardless of the wound size but in large defects, periodontal ligament width was significantly reduced with or without implants. In large wounds at 2 months, collagen implants inhibited bone regeneration and there was stronger staining for osteopontin and bone sialoprotein in the bone replacing the implant, indicating that collagen prolonged bone remodelling. We conclude that implantation of exogenous collagen affects alveolar bone healing but does not preserve the width of the regenerated periodontal ligament. Therefore collagen does not appear to contribute to homeostasis in the periodontium following wounding.     

Interrelation between alveolar bone and periodontal ligament repair after replantation of mature permanent incisors in monkeys

Interrelation between alveolar bone and periodontal ligament repair was studied in green Vervet monkeys. Maxillary central incisors were extracted. The storage medium for the extracted teeth was saline in an 18 min. extra-alveolar group and dry storage in a 120 min. extra-alveolar group. In the experimental groups, the labial bone plate was removed surgically and the teeth replanted. In the control groups, teeth with similar extra-alveolar periods were replanted into sockets with intact labial bone, The animals were sacrificed 8 weeks after replantation and the replanted teeth examined histometrically. Root resorplion and the position of the labial bone in relation to the cemento-enamel junction were registered for each tooth. A significant relationship was found between the extent of labial bone repair and the extra-alveolar period. Thus, teeth with I8 min. extra-alveolar period showed almost complete repair of the labial bone plate, whereas teeth with an extra-alveolar period of 120 min. showed a mean position of labial bone 3.7 mm from the pocket epithelium. The extent of root resorption was influenced by the extra-alveolar period alone and not by the presence or absence of alveolar bone. It is concluded that a vital periodontal ligament upon replanted mature teeth is able to induce the formation of new alveolar bone.     

Participation of periodontal ligament cells with regeneration of alveolar bone

BACKGROUND: It is important to clarify the participation of periodontal ligament (PDL) cells in the regeneration of alveolar bone to establish a reliable approach for obtaining periodontal regeneration. The aim of this study was to determine whether PDL cells play an important role in alveolar bone repair during the course of periodontal regeneration. METHODS: In an in vitro study, the expression of the osteoblast phenotype, such as alkaline phosphatase activity and parathyroid hormone-dependent 3',5'-cyclic adenosine monophosphate accumulation, was investigated in dog PDL cells (DPLC) and dog bone cells isolated from mandibles (DBC). In a related study, the roots of mandibular third premolars extracted from aged dogs were divided into a PDL(+) group, in which the PDL was preserved, and a PDL(-) group, in which the PDL was removed. These roots were respectively transplanted into surgically created bone cavities with buccal and interproximal bone defects in an edentulous area, prepared in advance by extraction of mandibular fourth premolars. These bone defects with the transplanted roots were completely covered with submerged physical barrier membranes. New bone formation and new connective tissue attachment, which require new cementum and insertion of functionally oriented new collagen fibers of periodontal ligament, were histomorphometrically assessed, and were compared between the PDL(+) and PDL(-) groups 6 weeks after transplantation. RESULTS: Both cultured DPLC and DBC exhibited the osteoblast phenotype. New connective tissue attachment was observed only in the PDL(+) group. However, alveolar bone was almost completely regenerated to the original bone height in both the PDL(+) and PDL(-) groups, and the amount of newly formed bone was not significantly different between the 2 groups. CONCLUSIONS: DPLC retain the capability to differentiate into an osteoblast lineage and may act in the regeneration of periodontal ligament with new cementum formation, whereas these cells may have a limited influence on alveolar bone formation during the course of periodontal regeneration.     

Application of periodontal ligament cell sheet for periodontal regeneration: a pilot study in beagle dogs

OBJECTIVE: The ultimate goal of periodontal treatment is to regenerate the damaged periodontal support. Although periodontal ligament (PDL) cells are essential for periodontal regeneration, few studies have reported the transplantation of periodontal ligament cells to periodontal defects. We developed a new method to apply periodontal ligament cells as a sheet to the defect. The aim of this study was to investigate the periodontal healing after application of the periodontal ligament cell sheet in beagle dogs. METHODS: Autologous periodontal ligament cells were obtained from extracted premolars of each beagle dog. Periodontal ligament cell sheets were fabricated using a temperature-responsive cell culture dish. Dehiscence defects were surgically created on the buccal surface of the mesial roots of bilateral mandibular first molars of each dog. In the experimental group (five defects), periodontal ligament cell sheet with reinforced hyaluronic acid carrier was applied to the defect. Only the hyaluronic acid carrier was applied to the contralateral side as a control (five defects). Eight weeks after surgery, the animals were sacrificed and decalcified specimens were prepared. Healing of the periodontal defects was evaluated histologically and histometrically. RESULTS: No clinical signs of inflammation or recession of gingiva were observed in both experimental and control groups. In the experimental group, periodontal tissue healing with bone, periodontal ligament and cementum formation was observed in three out of five defects. In the control group, such periodontal tissue formation was not observed except in one defect. Histometric analysis revealed that the formation of new cementum in the experimental group was significantly higher than that in the control group. CONCLUSION: The periodontal ligament cell sheet has a potential to regenerate periodontal tissue and may become a novel regenerative therapy.     

A Prospective,Case‐Controlled Study Evaluating the Use of Enamel Matrix Derivative on Human Buccal Recession Defects: A Human Histologic Examination

Background: Connective tissue grafts (CTGs) and coronally advanced flaps (CAFs) do not regenerate periodontal attachment apparatus when used to treat gingival recessions (GRs). Instead of generating new bone, cementum, and inserting periodontal ligament fibers, CTG+CAF repairs through a long epithelial junction and connective tissue attachment. Enamel matrix derivatives (EMDs) have demonstrated proof‐of‐principle that periodontal regeneration can be achieved, although data are limited. Methods: Three patients, each requiring extraction of four premolars before orthodontic treatment, were enrolled in a randomized, open‐label study. Two months after induction of Miller Class I and II GR, each patient received EMD+CAF for three teeth and CTG+CAF for one tooth for root coverage. Nine months after root coverage, all four premolars from each of the three patients were surgically extracted en bloc for histologic and microcomputed tomography (micro‐CT) analysis, looking for evidence of periodontal regeneration. Standard clinical measurements, radiographs, and intraoral photographs were taken over prescribed time points. Results: Seven of the nine teeth treated with EMD+CAF demonstrated varying degrees of periodontal regeneration, detailed through histology with new bone, cementum, and inserting fibers. Micro‐CT corroborated these findings. None of the three teeth treated with CTG+CAF showed periodontal regeneration. Clinical measurements were comparable for both treatments. One instance of root resorption and ankylosis was noted with EMD+CAF. Conclusions: EMD+CAF continues to show histologic evidence of periodontal regeneration via human histology, this being the largest study (nine teeth) examining its effect when treating GR. The mechanism of action, ideal patient profile, and criteria leading to predictable regeneration are in need of further exploration.     

Periodontal regeneration following implantation of cementum and periodontal ligament-derived cells

Nuñez J, Sanz‐Blasco S, Vignoletti F, Muñoz F, Arzate H, Villalobos C, Nuñez L, Caffesse RG, Sanz M. Periodontal regeneration following implantation of cementum and periodontal ligament‐derived cells. J Periodont Res 2012; 47: 33–44. © 2011 John Wiley & Sons A/S Background and Objective: The periodontal regeneration of bone defects is often unsatisfactory and could be largely improved by cell therapy. Therefore, the purpose of this study was to evaluate the regenerative potential of implanting canine cementum‐derived cells (CDCs) and canine periodontal ligament‐derived cells (PDLDCs) in experimentally created periodontal intrabony defects in beagle dogs. Material and Methods: Cells were obtained from premolars extracted from four beagle dogs. Three‐wall intrabony periodontal defects, 3 mm wide and 4 mm deep, were surgically created in their second and fourth premolars and plaque was allowed to accumulate. Once the defects were surgically debrided, periodontal regeneration was attempted by random implantation of collagen sponges embedded with 750,000 CDCs, 750,000 PDLDCs or culture medium. After 3 mo of healing, specimens were obtained and periodontal regenerative outcomes were assessed histologically and histometrically. Results: The histological analysis showed that a minimal amount of new cementum was formed in the control group (1.56 ± 0.39 mm), whereas in both test groups, significantly higher amounts of new cementum were formed (3.98 ± 0.59 mm in the CDC group and 4.07 ± 0.97 mm in the PDLDC group). The test groups also demonstrated a larger dimension of new connective tissue, resulting in a significantly more coronal level of histological attachment. Conclusion: This proof‐of‐principle study suggests that cellular therapy, in combination with a collagen sponge, promoted periodontal regeneration in experimental intrabony periodontal defects.     

Root development of rat tooth germs implanted in the tooth socket and in the subcutaneous tissue

Objective: This study was designed to investigate root development of a rat tooth germ implanted in a tooth socket or in a subcutaneous region. Materials and methods: Tooth germs of the upper left first molars in 2‐week‐old rats were extracted and implanted in the original tooth socket or in the subcutaneous region of the back. The upper right first molar was used as a control. The rats were fixed in weeks 1, 2, 4, 8 and 12. The root development was examined quantitatively with X‐ray radiographic morphometry. The cellular activity of producing matrix proteins was assessed using in situ hybridization for type I collagen. Results: Root development was observed in the implanted teeth in the tooth socket as also in the control teeth. In contrast, roots hardly developed in subcutaneously implanted teeth. Histology showed that periodontal ligaments were arranged around roots of implanted teeth in the tooth socket as around control teeth, but few periodontal ligaments were identified in the subcutaneous implantation. Dentin and cementum formed in both the implanted teeth as also in the control teeth and odontoblasts, cementoblasts and cementocytes expressed type I collagen. Conclusion: Tooth sockets may possess specific environments that allow root development of a tooth germ.     

Histologic and clinical evaluation of an allogeneic bone matrix for the treatment of periodontal osseous defects

The objective of this study was to evaluate the potential of an allogeneic bone matrix (Grafton, Osteotech) to regenerate new bone, new cementum, and a new periodontal ligament around teeth previously contaminated by bacterial plaque. Four patients with chronic advanced periodontitis and who were scheduled for full-mouth extraction were enrolled in the study. One patient dropped out from the study before any therapy began. One tooth with an intraosseous defect in each patient was selected for treatment. Measurements of probing depth, gingival recession, and clinical attachment level were made. After flap reflection, a root notch was placed at the apical level of calculus, the root was debrided, and allogenic bone matrix was inserted into the defect. After 6 months of healing, the teeth were removed en bloc and evaluated histologically for a new attachment apparatus. Two of the three teeth demonstrated regeneration of new bone, cementum, and periodontal ligament.     

Periodontal attachment level of extractions presumably performed for periodontal reasons

BACKGROUND/AIMS: The aim of this study was to analyse the residual periodontal attachment in teeth extracted by East German dentists in order to determine a possible 'forceps level'. METHODS: Out of about 8000 extracted teeth collected from a dental waste disposal company, 500 teeth were randomly selected. After exclusion of wisdom teeth and premolars extracted for orthodontic reasons (intact teeth with attachment > 90%), coronal and root caries, fillings, pulp exposure and incomplete root fillings (based on X-rays) were registered. The periodontal ligament was stained with 1% Fuchsin Red and measured with a light microscope. RESULTS: For intact teeth (DF = 0, periodontal disease definition I), the mean periodontal attachment (50.5% +/- 16.0) was significantly lower than for teeth with carious defects or fillings (64.7% +/- 18.8. unpaired t-test: p < 0. 00 1). There was a marked increase in frequency of extractions in intact teeth below 70% periodontal attachment and 37% were extracted at attachment levels between 50 and 69%. Teeth with pulpal involvement showed significantly different frequency distributions and mean attachment values (77.9% +/- 17.8) than the remaining teeth (periodontal disease definition II; 55,2% +/- 15.5). CONCLUSIONS: A considerable number of teeth with no or minor coronal destruction were extracted at an attachment level of 50-70%, regardless of the tooth type. The threshold for 'periodontal' extractions seem to be too low and undifferentiated, which calls for an improvement in knowledge of periodontal diagnosis and treatment.