Soft tissue‐related complications and management around dental implants

Implant installation for replacing missing teeth is a frequent treatment procedure with high long‐term survival and success rates. However, the success of implant therapy may be jeopardized by several complications related to mistakes in treatment planning, surgical procedure, management of hard and soft tissues, and infections. Increasing evidence suggests that the stability of the soft tissues surrounding osseointegrated dental implants may substantially influence long‐term clinical stability and esthetics. Therefore, when implant therapy is planned, the clinician must not only be able to perform the appropriate steps to maintain/create a stable soft tissue, but also needs to be aware of the potential sources for complications and possess the adequate knowledge for their appropriate management. The present paper provides an overview of the most important aspects related to the prevention and management of soft tissue‐related complications in conjunction with implant therapy. The current literature indicates that the presence of an adequate width of keratinized attached mucosa around dental implants may lead to better soft and hard tissue stability, less plaque accumulation, limited soft tissue recession, and lower incidence of peri‐implant mucositis. Proper implant positioning by carefully considering appropriate mesio‐distal and bucco‐lingual dimensions and implant angulation may prevent the loss of interdental soft tissues and development of soft tissue recessions. To optimize the width of keratinized attached mucosa, the appropriate soft tissue augmentation protocol should be selected for each particular indication. When the use of autogenous soft tissue grafts is planned, a thorough knowledge of the anatomical structures is mandatory in order to harvest soft tissue grafts of an appropriate quality and quantity and to avoid/minimize postoperative complications. Finally, the clinician needs to master the necessary steps in order to manage complications related to extensive bleeding and tissue necrosis that may occur in conjunction with soft tissue augmentation procedures.     

The effect of internal versus external abutment connection modes on crestal bone changes around dental implants: a radiographic analysis

Background: To the best of our knowledge, the influence of external versus internal implant–abutment connections on crestal bone remodeling has not been reported. The aim of the present study is to investigate the influence of the abutment connection on peri‐implant crestal bone levels (CBLs) using radiographic recordings. Methods: Radiographic recordings from 40 single‐tooth implants (20 external and 20 internal octagonal connections; one implant/patient) in 40 patients (15 males and 25 females; mean age: 54.3 years) were selected for analyses. The radiographic evaluation included the following: 1) linear bone change (LBC); 2) dimensional change (DC); and 3) angle between the implant and adjacent bone (AIB). Differences in LBC, DC, and AIB between implant placement and 1 year after loading for each system were evaluated using a paired t test. Comparison of LBC, DC, and AIB between systems at 1 year after loading was done using analysis of covariance. The significance level was set at P ≤0.05. Results: Radiographic CBLs (LBCs) were reduced at 1 year after loading compared to those at implant placement to reach statistical significance for the external connection (P = 0.000) but not the internal connection (P = 0.939). CBL changes were significantly greater for the external compared to the internal connection (P = 0.000). Similarly, the DC for the external connection was significantly greater compared to that for the internal connection (P = 0.004). Conclusion: Within the limitations of this study, the implant–abutment connection technology appears to have a significant impact on peri‐implant CBLs, with the external connection paralleled by a significant reduction of CBLs.     

The dimensions of keratinized mucosa around implants affect clinical and immunological parameters

Objectives: To investigate the association between keratinized mucosa (KM) width and mucosal thickness (MTh) with clinical and immunological parameters around dental implants. Methods: Sixty‐three functioning dental implants (3I osseotite) were examined. Clinical examinations included plaque index (PI), probing depth (PD), bleeding on probing (BOP), KM width, MTh and buccal mucosal recession (MR). Peri‐implant crevicular fluid (PICF) samples were collected for PgE2 assay. Results: KM width ranged from 0 to 7 mm (mean 2.5±2), MTh ranged from 0.38 to 2.46 mm (mean 1.11±0.4) and the mean MR was 0.62 mm, ranging from 0 to 3 mm. A negative correlation was found between MTh and MR (r=?0.32, P=0.01); Likewise, KM width showed a negative correlation with MR, periodontal attachment level (PAL) and PgE2 levels (r=?0.41, P<0.001; r=?0.26, P=0.04; r=?0.26, P=0.04, respectively). In contrast, a positive correlation was found between KM width and PD (r=0.27, P=0.03). When data were dichotomized by KM width, a wider mucosal band (>1 mm) was associated with less MR compared with narrow (≤1 mm) band (0.27 and 0.9 mm, respectively, P=0.001). A wider KM band was also associated with a greater PD (3.13 mm) compared with a narrow band (2.66 mm, P=0.04). Similarly, a thick mucosa (≥1 mm) was associated with lesser recession compared with a thin (<1 mm) mucosa (0.45 and 0.9 mm, respectively, P=0.04). Conclusion: The KM around dental implants affects both the clinical and the immunological parameters at these sites. These findings are of special importance in the esthetic zone, where thin and narrow KM may lead to a greater MR.     

Molecular biology in oral research

Molecular biology is a study of molecules that are associated with living organisms. In recent years major advances in molecular biology have had a strong impact on medical and dental science. The new knowledge has led to a change in strategies for controlling dental diseases. In the present review we give a short introduction to some major advances in dental research which are based on molecular biology methods. This includes studies of dental hard tissue formations, mucosal immunity, tissue degradation by proteolytic enzymes, and intercellular communication by surface carbohydrate structures.     

Optical phenomenon of peri-implant soft tissue. Part I. Spectrophotometric assessment of natural tooth gingiva and peri-implant mucosa

OBJECTIVES: The purpose of this study was to investigate the difference in optical appearance of the soft tissues labial to dental implants and to analyze the effects of titanium implant neck colors transmitted through the marginal mucosa. MATERIALS AND METHODS: Fourteen patients with 15 Straumann single implant replacements in the maxillary anterior region were recruited. Color measurements of the peri-implant mucosa of test sites and the gingivae of contralateral or adjacent natural teeth as controls were made at the facial aspect of the teeth using a spectrophotometer. The color data (CIELAB color coordinates; L*, a*, b* and C*) in five incremental areas of 1 x 2 mm from the gingival margin toward the apical direction were obtained. RESULTS: A significant difference existed (P<0.01) between the test site and the control site on the mean L* and b* values in all five incremental areas (area 1-5). In contrast, there was no significant difference in the mean a* values. Discrepancies between color distributions of soft tissues were stronger in areas close to the gingival margin and decreased toward the apical direction. The mean color difference DeltaE between the test site and the control site was 7.7 in area 1 and decreased toward area 5 with a value of 6.5. However, there was no statistical difference in each of the mean values of differences in optical data, DeltaL*, Deltaa* and Deltab*, when five incremental areas of the control and the test sites were compared. CONCLUSION: It was observed that the color of soft tissue around the titanium implant was significantly different compared with the gingiva of natural teeth. Significantly lower values of CIELAB color coordinates, L* and b* were found in the peri-implant soft tissue.     

Effect of loading on the development of nerve fibers around oral implants in the dog mandible

Occlusal forces cause stress which morphologically affects the supporting tissues of implants. The aim of this study was to examine the effects of occlusal forces on the distribution of neurofilament protein (NFP)-positive nerve fibers in the tissue of peri-implant bone. The bilateral 2nd, 3rd and 4th mandibular premolars and the 1st molars were extracted from three mongrel dogs. After 4 months of healing, 4 screw-type implants were inserted in the oral cavity. Three months after insertion, the implants on the molar site were loaded by occlusal forces, while those on the premolar site were unloaded. After a further 3 months, the dogs were sacrificed, and specimens were prepared for immunohistochemical NFP-positive staining by the labeled-streptavidin-biotin method. Many NFP-positive nerve fibers were found in the tissues of the loaded site when compared with the unloaded site. These fibers were localized in both the bone marrow space and in the peri-implant fibrous tissue. They had two types of nerve endings: simple free nerve endings, and nerve endings with tree-like ramifications. The present results suggest that loading by occlusal force causes an increase in the number of NFP-positive nerve fibers, many of which have free nerve endings in the peri-implant tissue. The possible role of these NFP-positive nerve fibers is discussed.     

Effects of cannabis smoking on oral soft tissues

Abstract – The oral effects of cigarette smoking have been well documented but the effects of cannabis smoke on the oral environment have been poorly documented. Three-hundred cannabis/tobacco/methaqualone smokers were examined. Two control groups consisting of 152 tobacco- and 189 non-smokers respectively were examined similarly. Health of the oral tissues and oral dryness was recorded. Lesions present included leukoedema, leukoplakia and numerous others. The only significant differences between lesions and conditions noted in cannabis users and controls occurred with respect to leukoedema, dry mouth and traumatic ulcer.     

Reproducibility of automated periodontal probing around teeth and osseointegrated oral implants

Three different probing devices (Audio‐Probe®, Florida‐Probe®, Peri‐Probe®) were tested in order to determine the clinical probing depth (CPD) around clinically stable oral implants and their homologous teeth and to evaluate their reproducibility. In all 37 patients. in the age range of 24–80 years, who had undergone periodontal therapy and placement of 1 or more oral implants (ITI®), were selected for the study. The CPD was determined on 75 oral implants in total and at 4 sites of both the implants and the control teeth at 3 visits, each 1 week apart. At the 1st visit, the Florida‐Probe® and the Audio‐Probe® were used. At the 2nd visit, the Florida‐Probe® and the Peri‐Probe® and, at the 3rd visit, again, the Florida‐Probe® and the Audio‐Probe® were used. At each visit bleeding on probing (BOP) was registered. A statistically significant ( P <0.05) difference between the mean scores of implant and tooth sites was found showing slightly higher values for implant sites. A tendency for the deeper pockets to bleed more frequently than the shallow pockets was observed. The comparisons of differences of the readings of the Audio‐Probe® on 2 different occasions were smaller than for the Florida‐Probe®. However, comparisons between 2 different probes showed significantly greater measurement errors than when comparing the probes alone. There was a tendency for the Peri‐Probe® to yield the highest and the Audio‐Probe® the lowest values in inflamed sites. It was concluded that all 3 probing devices appeared to have adequate reproducibility both around teeth and oral implants. For clinical use in daily practice, the Audio‐Probe® was found to be the most simple device with the highest 1 reproducibility.     

Quality and quantity of bone following alveolar distraction osteogenesis in the human mandible

PURPOSE: The purpose of this prospective study on humans were to evaluate (a) the clinical outcome of alveolar distraction osteogenesis for the correction of vertically deficient edentulous mandibular ridges, (b) the clinical outcome of dental implants placed in the distracted areas, and (c) the quality and quantity of the bone that had formed in the distraction gap. MATERIAL AND METHODS: Seven patients presenting vertically deficient edentulous ridges were treated by means of distraction osteogenesis with an intraoral alveolar distractor. Approximately 3 months after consolidation of the distracted segments, 20 ITI solid screw SLA implants were placed in the distracted areas. Three to 4 months later, abutments were connected and prosthetic loading of the implants started. During implant site preparation, bone biopsies were taken at the implant sites with trephine burrs for histologic and histometric analyses. RESULTS: The mean follow-up after the initial prosthetic loading was 18 months (range 12-24 months). The mean bone gain obtained at the end of distraction was 7 mm (range 5-9 mm). The cumulative success rate of implants 2 years after the onset of prosthetic loading was 95%, whereas the survival rate of implants was 100%. The newly formed bone consisted of woven bone reinforced by parallel-fibered bone with bone marrow spaces between the bone trabeculae. The bone area fraction in the distraction region ranged from 21.6% to 57.8% (38.5+/-11.7%). DISCUSSION AND CONCLUSIONS: Results from this study showed that (a) distraction osteogenesis is a reliable technique for the correction of vertically deficient edentulous ridges, (b) the regenerated bone withstood the functional demands of implant loading, (c) survival and success rates of implants placed in the distracted areas were consistent with those of implants placed in native bone, and (d) there is sufficient bone volume and maturity in the distracted region for primary stability of the implant.     

Relationship between buccal mucosa ridging and viscoelastic behaviour of oral mucosa

The aim of this study was to clarify the relationship between the buccal mucosa ridging (BMR), which has been mentioned to be a clinical sign of clenching, and the viscoelastic behaviour of oral mucosa. Twenty-three people with BMR and 21 people without BMR participated as volunteers in this study. Measurements of viscoelastic behaviour were performed using a suction viscoelastic meter on central part of lower labial mucosa. A suction pressure of 300 hPa was applied for 2 s and then released for 2 s, and the time-dependent changes in the deformation of the mucosa over this 4 s were recorded as a deformation curve. Distensibility, remaining deformation and elastic recovery, which describe viscoelastic behaviour, were calculated by the deformation curve. These parameters were compared between groups with and without BMR. No significant difference was found in distensibility between the two groups (P=0·349). There were significant differences for the remaining deformation (P=0·012) and the elastic recovery (P=0·032), and the group with BMR showed higher remaining deformation and lower elastic recovery than the group without BMR. Based on these results, it clarified that the BMR is related to the mucosal viscoelastic behaviour, in particular remaining deformation and elastic recovery.     

全新视角透视口腔黏膜组织工程

口腔黏膜组织工程主要应用于修复因肿瘤切除、牙周病、外伤等导致的软组织缺损.以前的组织工程研究主要围绕上皮细胞培养方法的发展以及结缔组织支架材料的研发开展,本文将对口腔黏膜组织工程替代物的培养模式、支架结构、基质功能及临床应用进行综述,展示组织工程的新视角及口腔黏膜组织工程的新应用.     

全新视角透视口腔黏膜组织工程

口腔黏膜组织工程主要应用于修复因肿瘤切除、牙周病、外伤等导致的软组织缺损。以前的组织工程研究主要围绕上皮细胞培养方法的发展以及结缔组织支架材料的研发开展,本文将对121腔黏膜组织工程替代物的培养模式、支架结构、基质功能及临床应用进行综述,展示组织工程的新视角及口腔黏膜组织工程的新应用。     

正常人口腔粘膜脱落细胞微核计数的研究

目的：了解正常人口腔粘膜中染色体损伤发生的情况,探讨不同部位细胞微核数的差异。方法：对90例正常口腔粘膜颊部,舌背,舌腹3个部位进行了脱落细胞微核计数的分析,并判定微核计数的影响因素。结果：正常口腔膜颊部细胞微核数大于舌背,舌腹细胞微核数（非吸烟组P＜0．05,吸烟组PK＜0．01）,非吸烟组细胞微核数远远低于吸烟组（P＜0．001）,多元回归分析显示吸烟量和吸烟年数同微核数有着密切的关系,结论：颊粘膜受到的各种理化刺激因素的作用较舌腹粘膜更直接,烟草刺激在肿瘤发生中具有重要的作用。     

Influences of internal tapered abutment designs on bone stresses around a dental implant: three-dimensional finite element method with statistical evaluation

Background: The aim of this study is to determine the effects of various designs of internal tapered abutment joints on the stress induced in peri‐implant crestal bone by using the three‐dimensional finite element method and statistical analyses. Methods: Thirty‐six models with various internal tapered abutment–implant interface designs including different abutment diameters (3.0, 3.5, and 4.0 mm), connection depths (4, 6, and 8 mm), and tapers (2°, 4°, 6°, and 8°) were constructed. A force of 170 N was applied to the top surface of the abutment either vertically or 45° obliquely. The maximum von Mises bone‐stress values in the crestal bone surrounding the implant were statistically analyzed using analysis of variance. In addition, patterns of bone stress around the implant were examined. Results: The results demonstrate that a smaller abutment diameter and a longer abutment connection significantly reduced the bone stresses (P <0.0001) in vertical and oblique loading conditions. Moreover, when the tapered abutment–implant interfaced connection was more parallel, bone stresses under vertical loading were less (P = 0.0002), whereas the abutment taper did not show significant effects on bone stresses under oblique loading (P = 0.83). Bone stresses were mainly influenced by the abutment diameter, followed by the abutment connection depth and the abutment taper. Conclusion: For an internal tapered abutment design, it was suggested that a narrower and deeper abutment–implant interface produced the biomechanical advantage of reducing the stress concentration in the crestal region around an implant.     

Dental Implants in Patients with Oral Lichen Planus: A Cross‐Sectional Study

Purpose: The main aim of this study was to evaluate the patients with oral lichen planus (OLP) and dental implants. Material and Methods: Three groups of 16 patients took part in the study. Group I patients had received dental implants and been diagnosed with OLP; Group II had not received implants but were diagnosed with OLP; Group III had implants but not OLP. Clinical observations and OLP symptoms were registered in each case. Periodontal pocket depth, implant mobility, bleeding upon probing, erythema, pain, and radiolucency around implants were measured. Patient quality of life was evaluated using OHIP 14. Results: Peri‐implant mucositis and peri‐implantitis were detected in 17.86% and 25% of the OLP‐implant group, while the control group with implants showed 18% and 16%. The implant survival rate in patients treated for OLP did not appear to differ from the survival rate among the general population. Quality of life was better among patients with implants and without OLP (p = .001). Conclusions: The results of the present study suggest that implants do not influence manifestations of OLP. OLP is not a risk factor for peri‐implantitis.     

组织工程化口腔黏膜支架材料的研究进展

随着组织工程技术的发展,近年来国内外许多学者致力于口腔黏膜组织工程的研究,取得了一定的成就,支架材料是黏膜组织工程的一个重要因素,本文对组织工程化口腔黏膜的支架材料研究作一简要综述。