Histomorphometrical and clinical comparison of submerged and nonsubmerged implants subjected to experimental peri-implantitis in dogs

OBJECTIVES: Soft and hard tissue healing around submerged and nonsubmerged versions of one dental implant design was evaluated in an experimental canine peri-implantitis model. MATERIAL AND METHODS: Forty-eight c.p. Ti-implants with integrated (one-piece=OPI) or screw-on (two-piece=TPI) abutments were inserted in edentulous mandibles of eight beagle dogs, one OPI and one TPI with connected abutments for nonsubmerged and one TPI without abutment (SMI) for submerged healing. After 3 months, all implants were functionally loaded, and at 4 months peri-implantitis was ligature-induced in one jaw side. Intravital polyfluorochrome labeling, monthly conventional radiography and gingival probing of all 48 implants were performed until sacrifice 8 months postimplantation. Undecalcified ground sections in the bucco-lingual and mesio-distal planes of four dogs (23 implants, one implant lost) were evaluated by light and fluorescence microscopy. The immunohistochemical and SEM-vascular corrosion cast results of the four other dogs (24 implants) will be reported elsewhere. Levels of alveolar bone-to-implant contact (ABICL), alveolar crest (ACL) and junctional epithelium-to-implant contact were determined by computer-assisted histometry. Peri-implant alveolar bone loss (=saucerization) was assessed on the radiographs and calculated as ACL minus ABICL from histometric data. RESULTS: Around SMIs and OPIs without ligature less plaque adhesion and lower gingival indices were found when compared to TPIs. Radiologically, all ligatured, but also some nonligatured implants showed alveolar bone loss. Histometry demonstrated reduced ABICL around all these implants. Saucerization was more pronounced on the lingual and mesio-distal sides. Particularly around TPIs, bone resorption was still active or bone formation was impaired on fluorochrome labeling. Only around SMIs and one OPI without ligature continuing alveolar bone formation reflected by gains in ABICL were found. CONCLUSION: The clinical and histometric results of this study demonstrate that healing of submerged SMIs was not impaired by the two-stage procedure, resulting in equally good healing as around nonsubmerged OPIs. However, peri-implantitis plaque-induced by ligature and/or dilated abutment connection microgaps in TPIs affected alveolar bone-to-implant contacts more than transmucosal or submerged healing mechanisms.     

Effect of treatment delay upon pulp and periodontal healing of traumatic dental injuries – a review article

Abstract – Based on an analysis of the literature concerning parameters influencing the prognosis of traumatic dental injuries, few studies were found to have examined possible relationships between treatment delay and pulpal and periodontal ligament healing complications. It has been commonly accepted that all injuries should be treated on an emergency basis, for the comfort of the patient and also to reduce wound healing complications. For practical and especially economic reasons, various approaches can be selected to fulfill such a demand, such as acute treatment (i.e. within a few hours), subacute (i.e. within the first 24 h), and delayed (i.e. after the first 24 h). In this survey the consequences of treatment delay on pulpal and periodontal healing have been analyzed for the various dental trauma groups. Applying such a treatment approach to the various types of injuries, the following treatment guidelines can be recommended, based on our present rather limited knowledge of the effect of treatment delay upon wound healing. Crown and crown/root fractures : Subacute or delayed approach. Root fractures : Acute or subacute approach. Alveolar fractures: Acute approach (evidence however questionable). Concussion and subluxation : Subacute approach. Extrusion and lateral luxation : Acute or subacute approach (evidence however questionable). Intrusion : Subacute approach (evidence however questionable). Avulsion : If the tooth is not replanted at the time of injury, acute approach; otherwise subacute. Primary tooth injury : Subacute approach, unless the primary tooth is displaced into the follicle of the permanent tooth or occlusal problems are present; in the latter instances, an acute approach should be chosen. These treatment guidelines are based on very limited evidence from the literature and should be revised as soon as more evidence about the effect of treatment delay becomes available.     

Autotransplantation of immature third molars: influence of different splinting methods and fixation periods

Abstract  – Different data were published documenting the influence of fixation methods and periods on the outcome of autotransplantations of teeth. Besides studies reporting increased ankylosis and disturbances of pulpal revascularization following rigid or extended fixation, there are studies revealing no connection in this matter. The clinical and radiological results of 76 transplanted germs of third molars were to be assessed after a rigid fixation for 4 weeks or after a suture splinting for 7 days and compared with each other. The choice of fixation method depended on the initial stability of the transplant. After a mean observation period of 3.4 years (range 1.0–6.1 years), 92.9% of the teeth stabilized with a suture, but only 73.5% fixed with an acid-etch composite and wire splint could be classified as successful ( P  = 0.029). The significant increases in ankylosis ( P  = 0.036) and pulp necrosis ( P  = 0.041) were the factors for the less favorable results of the rigidly fixed teeth. Our data support the results of other experimental and clinical studies with regard to the negative influences of an extended and rigid fixation on the success of tooth transplantation. However, apart from a correlation with the method and period of fixation, we also suspect the influence of an incongruity between the transplant and recipient site.     

Replantation of 45 avulsed permanent teeth: a 1-year follow-up study

Abstract –  Thirty-four patients with 45 avulsed and replanted permanent teeth were followed for 1 year. All teeth were soaked in tetracycline before replantation. In addition, enamel matrix derivative was used in teeth with dry storage times exceeding 30 min. Splinting was carried out with a non-rigid titanium splint and was limited to 7–10 days. Within that period, root canal treatment was begun in all teeth with a closed apex, whereas teeth with an open apex and ideal post-traumatic storage were not instrumented. All patients were given tetracycline systematically for 10 days. The survival rate of replanted avulsed permanent teeth was 95.6% at the 1-year follow-up. In 82.2%, root canal treatment was performed. Pulp survival was never observed, but three teeth had pulp canal obliteration. Normal periodontal healing was observed in 57.7% of teeth; 42.3% of teeth showed external root resorption (28.9% replacement resorption, 6.7% infection-related resorption, 6.7% surface resorption). The occurrence of replacement resorption correlated with the period of extraoral dry storage. Compared with other clinical studies on avulsed and replanted teeth, the present study reports a higher percentage of periodontal healing. The favorable treatment outcome may be associated with a strict protocol to enforce endodontic treatment, the use of topical and systemic tetracycline, and the relatively high number of ideally stored teeth following avulsion. In contrast, the present study has a follow-up period limited to 1 year.     

Basic fibroblast growth factor and epidermal growth factor reverse impaired ulcer healing of the rabbit oral mucosa

BACKGROUND: The therapies for refractory ulcers on the oral mucosa are symptomatic and very unsatisfactory. We hypothesized that application of growth factors might be able to achieve successful remission of the lesion. We evaluated the effects of systemic administration and topical application of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) on impaired wound healing of ulcers in the rabbit gingiva. METHODS: Almost uniform round ulcers could be created on the gingiva of the rabbits by chemical injury with acetic acid. When the submandibular glands were removed or i.v. injection of cisplatin (CDDP) and peplomycin sulfate was performed before ulcer formation, healing of the ulcers took longer than in untreated rabbits. To ascertain whether or not human EGF and bFGF affect rabbit cells, we first examined the effects of EGF and bFGF on the proliferation of the cells derived from rabbit gingiva. We then applied EGF or bFGF in these impaired healing models. RESULTS: EGF and bFGF promoted proliferation of the fibroblasts, and EGF also promoted proliferation of the keratinocytes isolated from gingival tissue of rabbits in vitro. Systemic injections of EGF and bFGF in rabbits, which had their submandibular glands removed, and topical application of bFGF accelerated healing of ulcers created in rabbits injected with CDDP and peplomycin sulfate. The ability of bFGF to promote the healing of ulcers was much greater than that of EGF. CONCLUSION: Basic FGF may be effective for refractory oral mucosal lesions.     

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     

补锌对骨折区和非骨折区骨锌含量影响的比较研究

目的　本研究主要分析损伤后外源性锌剂在不同类型骨中的沉积规律。方法　选用 2 4只新西兰兔 ,首先形成双侧颧骨骨折模型。术后 1、2、3、4周分别测定骨折区 (颧骨 )和非骨折区 (下颌骨和颅骨 )骨锌的含量。结果　外源性锌剂在骨折区和非骨折区的沈积量均明显增加 ,但增加的时相不同 ;骨折区第 2周对锌的需要量最大 ,非骨折区第 2周骨锌含量明显下降。结论　外源性锌剂进入机体后主要贮存在骨髂系统 ,骨折愈合需要锌的参与 ,骨折后 2周内应注意对锌的补充     

Placement of a porous membrane underneath the mucoperiosteal flap and its effect on periodontal wound healing in dogs

This study was designed to investigate the healing of surgically induced, horizontal periodontal defects in dogs following placement of a biocompatible, porous polytetrafluorethylene membrane around the roots of the treated teeth and to compare the healing to that of control teeth without membrane. Mandibular premolar teeth of 5 beagle dogs were used for experimentation. Specimen blocks were removed 3 months postoperatively for histological evaluation of contralateral experimental and control teeth. Mean apical migration of junctional epithelium among the experimental surfaces amounted to 0.1 mm as compared to 1.3 mm for the control surfaces. Accordingly, the amount of connective tissue attachment, defined by the distance from the base of the junctional epithelium to the apical termination of root planing, was greater for experimental than for control surfaces. As this increased amount of connective tissue attachment was associated with more coronal bone apposition, a periodontal ligament space was more prevalent in experimental than in control surfaces. A limited amount of ankylosis was observed for both experimental and control surfaces. Root resorption was more prevalent in control than in experimental surfaces. Conceivable reasons for the differences in healing between experimental and control teeth are discussed.     

骨桥蛋白在新生大鼠背部皮肤创伤愈合过程中的表达

目的：检测骨桥蛋白（osteopontin,OPN）在新生大鼠皮肤及创伤愈合过程中的表达,探讨OPN参与皮肤创伤愈合的可能机制。方法：在7d龄SD大鼠背部皮肤做直径为1ClTI的圆形全层皮肤切口,运用免疫组织化学方法检测OPN阳性细胞在皮肤及创伤愈合过程中的分布情况,并分别运用RT—PCR及Westernblot检测OPN在创伤愈合不同时间点（1、3、5及7d）的表达情况。结果：在大鼠正常皮肤,免疫组织化学结果显示OPN阳性细胞分布在毛囊、皮脂腺及汗腺,表皮则无表达;RT—PCR及Westernblot均未检测到OPN在正常皮肤中的表达。从创伤后第1天起,OPN阳性细胞开始集中分布在创伤边缘的真皮部位,且在第3天达到高峰,第、5天表达开始减弱。RT—PCR及Westemblot结果一致．OPN相对表达量在第3天达到高峰。结论：研究结果表明OPN参与了皮肤创伤愈合,尤其在创伤修复的炎症期及细胞外基质沉积期。     

Periodontal wound healing responses to varying oxygen concentrations and atmospheric pressures

Oxygen effects on healing gingival wedge excisions were tested using Sprague-Dawley rats. 40 operated controls were maintained at normal pressure in room air. 3 experimental groups of 40 rats each were exposed for 90 min daily to one of the following: (1) 20.8% oxygen at 2.4 atmospheres pressure, (2) 100% oxygen at 1 atmosphere, or (3) 100% oxygen at 2.4 atmospheres. 5 animals in each group were sacrificed at the following times: 30, 54, 78 h and weeks 1, 2, 3, 6 and 12. Histometric analysis was performed using light microscopy. The connective tissue healing above a reference notch on the maxillary first molar mesial root was assessed. The controls failed to show healing comparable to experimental animals until the end of 2 weeks. Enhanced connective tissue healing above the notch was most significant (p less than or equal to 0.05) in the 2.4 atmospheres pressure groups at 3 and 6 weeks when compared to controls. However, by 12 weeks, no significant differences could be detected. New cementum formation was rare and occasional root resorption was observed. Early connective tissue adaptation does not imply eventual attachment as epithelial downgrowth progressively displaced the connective tissue adjacent to the root in both experimental and control groups of this study.     

Subpopulations of fetal-like gingival fibroblasts: characterisation and potential significance for wound healing and the progression of periodontal disease

Wound healing in the adult is commonly compromised by excessive scar formation. In contrast, fetal wound healing is a regenerative process characterised by the conspicuous absence of scarring. Available evidence suggests that phenotypic differences between fetal and adult fibroblasts are important determinants of these distinct modes of tissue repair. In this context, a number of groups (including our own) have documented differences between fetal and adult fibroblasts with respect to such potentially relevant characteristics as migratory activity, motogenic response to cytokines and the synthesis of motility factors, cytokines and matrix macromolecules. The oral mucosa appears to be a privileged site in the adult in that it continues to display a fetal-like mode of wound healing. Data are presented in this review indicating that a subpopulation of gingival fibroblasts expresses several 'fetal-like' phenotypic characteristics. These observations are discussed in terms of both the continued expression of a fetal-like mode of wound healing in the oral mucosa and the possible differential involvement of distinct fibroblast subpopulations in the progression of periodontal disease.     

Replantation of 400 avulsed permanent incisors. 1. Diagnosis of healing complications

Abstract A material of 322 patients with 400 avulsed and replanted permanent teeth were followed prospectively in the period from 1965 to 1988 (mean observation period=5.1 yrs). The age of the patients at the time of replantation ranged from 5 to 52 yrs (mean =13.7 yrs and median =11.0 yrs). Standardized patient records were used through the entire period in order to obtain valid data concerning the extent of injury and treatment provided. At the follow–up period, pulpal and periodontal healing were monitored by clinical examination, mobility testing and standardized radio–graphic controls. Thirty–two of the replanted teeth (8%) showed pulpal healing. When related to teeth with incomplete root formation, where pulpal revascularization was anticipated (n = 94) the frequency of pulpal healing was 34%. Periodontal ligament healing (i.e. with no evidence of external root resorption) was found in 96 teeth (24%). Gingival healing was found in 371 teeth (93%). During the observation period, 119 teeth (30%) were extracted. Tooth loss was slightly more frequent in teeth with incomplete root formation at the time of replantation than in teeth with completed root formation.     

The effect of saline storage before replantation upon dry damage of the periodontal ligament

Abstract The effect of 30 min of saline storage before replantation of teeth, which had been dried out for 30 min, was studied in 10 Green Vervet monkeys (Cercopithecus aethiops). Maxillary central incisors were extracted and dried out for 30 min, after which 1 incisor was replanted and the other transferred to a saline solution for 30 min before replantation. No splinting or endodontic treatment was carried out. The teeth were examined after 8 wk. Histometric analysis showed identical extent of root resorption in the 2 groups, with ankylosis being the dominant resorption type, and with very limited pulpal repair in either group. It is concluded that saline storage under the experimental conditions chosen had no effect on development of root resorption or pulpal repair, presumably because 30 min dry storage had inflicted close to maximal damage on the periodontal ligament at the root surface. On the other hand, it is of clinical importance that a certain delay in the replantation procedure does not influence periodontal and pulpal healing, as long as the tooth is kept in saline storage. This suggests that replantation under these conditions can be reserved for dental professionals, rather than favoring immediate replantation by anyone ‘on-the-spot’.     

种植体周围骨愈合及骨缺损愈合中神经生长因子作用的实验研究

目的观察神经生长因子(NGF)在种植体周围骨愈合及骨缺损愈合中的表达,探讨NGF在骨愈合中的作用。方法选用29只SD大鼠,按观察时间不同随机分4组,每组大鼠随机选取4只,左侧后大腿股骨植入种植体设为种植组;另外3只左侧后大腿股骨备洞设为骨缺损组。右侧后大腿均无骨损伤,设为对照组。术后取股骨标本拍X线片,去种植体制作切片行HE染色、NGF免疫组化染色。剩余1只大鼠取颌下腺作为NGF染色阳性对照。结果种植体无松动,种植体-骨结合良好。免疫组化染色结果显示,种植组及骨缺损组在愈合过程中可见骨髓基质细胞、骨母细胞、骨细胞、成纤维细胞及成骨细胞有NGF阳性染色。对照组相同位置骨组织中,未见NGF阳性染色。统计学结果显示,1周时种植组和骨缺损组NGF阳性染色率的比较有统计学差异;2、3、4周时2组NGF阳性染色率比较无统计学差异。结论 NGF可能参与了种植体周围骨愈合及骨缺损愈合过程。在种植早期,植体周围的NGF分泌情况与骨缺损愈合不同,较晚时期二者相同。     

Periodontal healing of replanted dog teeth stored in Viaspan, milk and Hank's balanced salt solution

Abstract This study examined, histologically, periodontal healing and root resorption of replanted dogs teeth stored in Viaspan for different time periods and compared these healing patterns to those after storage in milk or Hank's balanced salt solution (HBSS). Seventy-two beagle incisors were endodontically treated, extracted, randomly divided and placed in Viaspan or milk for 6, 12, 24 and 36 h, and Viaspan or HBSS for 36, 48, 72 and 96 h, after which they were replanted. Four negative control teeth were immediately replanted while four positive controls were allowed to dry for one hour before replantation. All replanted teeth were splinted for 14 days. Two months after replantation the clogs were killed and the teeth histologically examined for healing of the supporting tissues. For Viaspan neither replacement nor inflammatory root resorption was seen after 6 and 12 h storage. A statistically significant rise in the incidence of replacement resorption was seen at 24, 36 and 48 h which decreased again at 72 and 96 h to levels equal to storage for 6 and 12 h. The occurrence of inflammatory root resorption was low and significantly increased only at 48 h after which it decreased significantly again. Viaspan proved superior to milk as a storage medium. Teeth stored in HBSS showed healing results similar to those stored in Viaspan.     

Observations on the initial stages of healing following human experimental gingivitis A clinical and morphometric study

The aim of the present study was to investigate stereologically the histologic alterations occurring during gingival healing after experimental gingivitis and to compare clinical parameters with histological findings. 8 dental students volunteered for the investigation. After a prophylaxis, they performed optimal oral hygiene to reach mean plaque and gingival indices approaching zero. They then abolished all oral hygiene procedures for a period of 21 days. After this experimental gingivitis phase, they again performed optimal oral hygiene for 8 days to restore gingival health. At days 0, 1, 2, 4 and 8 after experimental gingivitis, the plaque index (PlI), the gingival index (GI) and the gingival exudate flow rate (GEFR) were assessed and their buccal gingiva was biopsied. Point counting procedures were performed at 2 different levels of magnification on light microscopic sections to estimate the volume fractions of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The relative numbers of fibroblasts, polymorphonuclear neutrophils, lymphocytes, plasma cells and macrophages were estimated by counting the number of profiles of these cells in a specific connective tissue area adjacent to the apical end of the junctional epithelium. A rapid drop in the PlI was noted with increasing time after oral hygiene, followed by a slower decrease in the GI and GEFR scores. The histological picture during the entire experiment was that of an initial gingival lesion. At day 0, no chronic inflammation of the gingiva characterized by a predominance of plasma cells was observed.(ABSTRACT TRUNCATED AT 250 WORDS)