Alveolar Bone Reduction Research Articles

LASER-ASSISTED CROWN LENGTHENING: CLINICAL EFFICACY AND ADVANTAGES OVER CONVENTIONAL TECHNIQUES (SYSTEMATIC REVIEW)

Introduction: Crown lengthening is a widely recognized dental procedure with both aesthetic and functional purposes. It involves the reduction of periodontal hard and soft tissues to obtain supracrestal tooth length, resulting in longer clinical crowns and adequate supracrestal tissue attachment. Laser therapy has emerged as a promising alternative that is currently developing in the field of periodontics and offers several advantages. This review aims to synthesize the current research on the clinical efficacy of laser-assisted crown lengthening procedures and highlight their advantages over conventional methods. Review: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a comprehensive search was conducted in electronic databases PubMed, Scopus, Embase, and Google Scholar for human studies published from 2017 to April 2023. Out of 213 identified and screened studies, three original articles were included in the analysis. Two clinical trial studies used Er,Cr:YSGG while one study used Er:YAG for crown lengthening procedures involving gingiva and alveolar bone reduction, with a 3-month follow-up period. Compared to conventional crown lengthening, the laser-assisted approach showed comparable increases in clinical crown length. However, the laser-assisted group demonstrated better gingival margin stability, improved soft tissue healing, and minimal damage to adjacent tissues. Furthermore, there was a statistically significant lower bacterial load and less post-surgery pain with laser-assisted crown lengthening compared to the conventional method. Conclusion: In cases where both gingival and bone reduction are required, laser-assisted crown lengthening using Er,Cr:YSGG and Er:YAG can be considered a minimally invasive alternative with several advantages over conventional procedures.

Integration of conventional and digital surgical guide fabrication techniques for the partially edentulous patient: Reducing the number of surgical procedures for a complete arch implant-supported prosthesis.

Surgical procedures on partially edentulous patients for complete arch implant-supported prostheses involve remaining tooth extraction, alveolar bone reduction, and implant placement. Traditionally, partially edentulous patients undergo multiple surgeries, which extends the healing time and results in an extensively prolonged total treatment timeline. This technical article focuses on the fabrication of a more stable and predictive surgical guide to perform multiple surgical procedures in a single surgical appointment and planning a complete arch implant-supported prosthesis for the partially edentulous patient.

Guided maxillary full-arch implant rehabilitation using a novel chrome cobalt alveolar bone reduction guide

Full arch rehabilitations require precision in each step of the digital workflow, from virtual planning to implant placement. In guided surgery, accurate alveolar reduction and implant 3D positioning are crucial. This study presents the use of a novel chrome cobalt reduction guide for increased predictability of the rehabilitation protocol. The treatment protocol for a 27-year-old female who presented with failing maxillary dentition is presented. After evaluation of CBCT scans, an immediate fixed implant-based prosthesis was planned. Using implant planning software, a tooth-supported guide, a chrome-cobalt alveolar reduction guide, and an implant guide stacked onto the reduction guide were fabricated. The digital denture was created virtually pre-operatively. The surgery was performed under general anesthesia based on the consecutive use of the three guides. Four Neodent implants were placed in the maxilla and splinted through a metal bar incorporated into the interim prosthesis. Installation of the definitive prosthesis took place three months after the initial surgery. The mandible was rehabilitated with ten disilicate glass crowns following a digital workflow. The surgical procedure was uneventful and healing was successful. The rigidity of the reduction guide and the extra stabilizing pins facilitated implant placement and increased precision. The optimal 3-D positioning facilitated the rehabilitation process and the patient was highly satisfied with the results. Due to the increased stability and higher fracture resistance, this novel chrome-cobalt guide can facilitate the alveolar bone reduction procedure. This leads to higher predictability and patient satisfaction.

Postsurgical oral symptoms after insertion of one or two implants for mandibular overdentures: short-term results of a randomized clinical trial

ObjectiveThis randomized clinical trial aimed to compare the short-term postsurgical symptoms after insertion of one or two implants for retention of a mandibular overdenture. This study investigated whether the less invasive single-implant approach results in lower postoperative symptoms compared to the conventional two-implant overdenture.Materials and methodsPatients received new complete dentures and were randomly assigned to groups receiving one or two single-stage, early-loaded hydrophilic implants, inserted in the midline (n = 23), or the lateral incisor-canine area bilaterally (n = 24). Patient-reported postoperative symptoms were measured in a 0–100 visual analogue scale concerning pain in the surgical area, pain when chewing, bleeding, swelling, and unpleasantness. Data collection occurred 24 h and 7 and 21 days after surgery. Demographic and clinical features (smoking habit, classification of the residual ridges, and mucosal width and thickness at the implant sites), osteotomy for alveolar bone reduction, and surgery time were tested as predictors of symptom levels.ResultsOverall reported symptoms were mild and self-limited, with high rates of complete remission after the early loading period of 3 weeks. Progressive improvement of symptoms occurred from the 24-h to the 7-day and 21-day follow-ups (p < 0.001), similarly in both groups. None of the clinical predictors was significantly associated with the changes in symptoms.ConclusionsFindings suggest that the insertion of one or two implants may result in similar postoperative outcomes.Clinical relevanceThe severity of short-term postoperative symptoms may not be a critical factor for the decision between overdenture treatment with one or two implants.

Periodontal status evaluation in adolescents with hereditary rickets-like diseases

Hypophosphatemic rickets (HPPR) and hypophosphatasia (HPP) are hereditary pathologies accompanied by phosphorus metabolism problems and rickets deformities of the skeleton. Periodontal diseases, their diagnostic methods and factors affecting the progress of periodontal tissue damage are the least studied among the dental manifestations of HPPR and HPP. The aim of present cohort study was evaluation of periodontal tissue status in adolescents with HPPR and HPP. A dental examination of 20 adolescents aged 12 to 18 years with genetically and biochemically confirmed hereditary rickets-like diseases (E83.3 Disorders of phosphorus metabolism and phosphatases: hypophosphatemic rickets (HPPR) and hypophosphatasia (HPP)) was performed at the Pediatric Dentistry Department of Moscow State University of Medicine and Dentistry. In the present study clinical examination and cone-beam computed tomography (CBCT) data of patients were analyzed. According to the clinical examination data, a strong direct correlation was found between patient's age and the periodontal diseases severity (correlation coefficient r=0.87) in the study group. CBCT revealed the significant alveolar bone hypomineralization in adolescents with HPPR and HPP in comparison to control group (p<0.05). According to the measurement results obtained a strong inverse correlation between alveolar bone mineral density and alveolar bone reduction (correlation coefficient r= -0.74) in adolescents with hereditary rickets-like diseases was revealed. The diagnostic options of CBCT allow to begin comprehensive dental treatment of patients with HPPR and HPP at an early stage of periodontal disease preventing further development of pathology.

Effect of resveratrol on the progression of experimental periodontitis in an ovariectomized rat model of osteoporosis: Morphometric, immune-enzymatic, and gene expression analysis.

This study aimed to determine the role of resveratrol (RESV) on the progression of experimental periodontitis (EP) in ovariectomy rats (OVT). Estrogen deficiency is the main cause of osteoporosis and is related to higher periodontal attachment loss and reduction of alveolar bone. Zoledronate (ZLD) is an antiresorptive drug used to control osteoporosis but can lead to osteonecrosis of the jaw. RESV, a natural product, can reduce bone loss and control and prevent osteoporosis. Thus, this study aimed at investigating the effect of RESV on the progression of EP in estrogen-deficient rats. The animals were subjected to the OVT or sham surgery to induce estrogen-deficiency and then were divided into the groups: OVT+RESV (n: 10); OVT+PLAC (n: 10): OVT+placebo; OVT+ZLD +PLA (n: 10); OVT+RESV +ZLD (n: 10): OVT+RESV and ZLD; SHAM (n: 10): non-ovariectomized animals+placebo. To induce estrogen deficiency, the rats were subjected to ovariectomy. Experimental periodontitis was induced by the placement of a ligature at the second maxillary molars. Daily administration of the placebo solution, resveratrol (10mg/kg), and ZLD (0.1mg/kg) was carried out for a period 42days prior to initiation of EP, and then for another 28days following ligature placement. After euthanasia, the specimens were processed for micro-CT and morphometric analysis of bone loss (linear measurement), and the gingival tissue surrounding the maxillary second molar was collected for the quantification of inflammatory markers using Luminex/MAGPix, of oxidative stress markers using ELISA assay, and gene expression analysis of bone markers, by real-time PCR. Morphometric and micro-CT analysis showed higher bone loss and lower bone density, respectively, in OVT+PLAC when compared to the other groups (P<.05). ZLD treated groups had lower alveolar bone loss, as well as, higher density and percentage of bone volume, when compared to OVT+RESV and SHAM+PLAC groups (P<.05). IL-4 levels were significantly lower in the OVT+PLAC group versus OVT+ZLD +RESV and SHAM+PLAC (P<.05). NADPH oxidase (nicotinamide adenine dinucleotide phosphate oxidase) levels were significantly lower OVT+RESV group when compared to OVT+PLAC (P<.05). OPG mRNA levels were lower in OVT+PLAC compared with the SHAM+PLAC group (P<.05). It can be concluded that resveratrol modulated alveolar bone loss during experimental periodontitis progression in estrogen-deficient rats by downregulating NADPH oxidase levels.

Study of Alveolar Bone Status in Alcoholic Patients by Cone-Beam Computed Tomography

Background: Alcohol has a negative effect on humans, whether it is on the healthy or even economic side. It is considered a serious condition for the occurrence of many diseases threatening human life or may contribute to increasing their severity in addition to the negative impact on some parts of the human body. Aim of the study: To evaluate the alveolar bone status by measuring the alveolar bone crest level of the interproximal teeth in alcohol drinker individuals on CBCTs. Material and Methods: The current study included randomly selected male patients (n=294) who admitted to radiology units in some dentistry centers in Baghdad city, between the ages of 25 and 45 years. The selected male subjects were divided into three groups: control group (n=120), light alcohol drinking group (n=98) and heavy alcohol drinking group (n=76). The measurements of alveolar crest level were done on CBCT images by measuring a distance between the crest of alveolar bone and the “cementoenamel junction” in the interproximal teeth region. Results: Statistical analysis showed that there was a significant reduction in the alveolar bone crest level in the alcohol drinker groups as compared to the control non-drinker group at p-value ?0.05. In addition, the study also showed that there was a significant reduction of alveolar bone crest level in the maxilla as compared to the mandible between the alcohol drinker groups at p-value ?0.05. Conclusion: The study found there was a negative effect of “alcohol consumption” on the alveolar bone as it causes a reduction of alveolar bone crest level in the interproximal areas of teeth. Clinical significance: The study confirms the damage of alveolar bone reduction as a result of the long-term consumption of alcohol.

Fully Digital Workflow with Magnetically Connected Guides for Full-Arch Implant Rehabilitation Following Guided Alveolar Ridge Reduction.

This technique report describes a fully digital workflow in which two surgical guides (i.e. one for alveolar bone reduction and the other for implant placement) are magnetically connected to ensure stability during full-arch implant surgery following guided bone reduction. Digital prosthesis design as well as virtual bone reduction and implant planning are developed from the superimposition of facial, intraoral and CBCT scans. With this technique, different surgical guides and interim poly(methylmethacrylate) (PMMA) fixed prosthesis are precisely connected with magnets after being digitally designed and 3D-printed. As a result, such magnetic connection allows for satisfactory stability of the implant surgical guide, as well as of the interim fixed PMMA fixed prosthesis during capture of screw-retained abutments.

Sex diff erences in Late Iron Age Northeast Estonia as indicated in dental pathologies and enamel hypoplasia

Study of dental pathologies is important in investigating the health and diets of past populations. Dental pathologies of adult peoples show nutritional and hygienic habits in adulthood, but childhood metabolic stresses can be observed in the occurrence of linear enamel hypoplasia (LEH). Dental hard tissue pathologies (caries, pre mortem tooth loss, abscesses, calculus, reduction of alveolar bone, molar attrition) and LEH were observed over 15 years in individuals from Jõuga cemetery (11th–16th cc. Northeast Estonia). The aim of the study was to trace sexual differences in diet and subsistence patterns through an analysis of dental pathology.

Effects of T helper 1 cells and T helper 17 cells secreting cytokines on rat models of experimental periodontitis

Objectvie: To investigate the effects of secreting cytokines interferon-gamma (IFN-γ) and interleukin-17 (IL-17) of T helper 1 cells (Th1) and T helper 17 cells (Th17) on the peripheral blood and alveolar bone destruction, so as to provide a new explanation for cellular immunity-mediated alveolar bone destruction. Methods: Eighteen eight-week-old male Sprague-Dawley rats were divided, randomly and equally, into 3 groups: lipopolysaccharide (LPS) group, ligation group and normal control group. In the LPS group, Escherichia coli LPS was injected into the alveolar mucosa on the buccalmedian site of the left upper first molar, while the right upper first molar was injected with equal volume of physiological saline as self-controls. The injections were performed every other day for four times totally. In the ligation group, the left upper first molars were ligatured with 0.2 mm orthodontic cords, while the right upper first molars were left untreated as self-controls, and supplemented with high-sugar diet to promote the periodontitis status. The rats in normal control group were fed normally. The concentrations of IFN-γ and IL-17 in peripheral blood were measured using enzyme linked immunosorbent assay (ELISA) method at the fourth week after the start of injection and at the eighth week after ligation. The histological of periodontal tissues were observed after hematoxylin-eosin (HE) staining and osteoclast count was performed under light microscope. The histological of osteoclasts were observed after tartrate-resistant acid phosphatase (TRAP) staining. Expression of IFN-γ and IL-17 were detected by immunohistochemical assay. Results: The concentrations of IFN-γ in peripheral blood of LPS group [(185.0±50.7) ng/L] and ligation group [(202.9±60.4) ng/L] were significantly higher than that of normal control group [(106.3±17.2) ng/L](P<0.05). Meanwhile, histological examination showed inflammatory cells infiltration in the gingival epithelium, the height reduction of alveolar bone accompanied with absorption lacuna. There were significantly higher HE and TRAP stained osteoclasts in LPS group (9.50±1.05) and ligation group (10.83±1.17) than that in controlgroup (0.33±0.52)(P<0.05). Moreover, the expressions of IL-17 in alveolar bone absorption area of LPS group and ligation group were significantly stronger than that in control group (P<0.05). Conclusions: The rat models of experimental periodontitis and alveolar bone resorption could be successfully established by means of ligationand LPS injection, respectively. The periodontal inflammatory responses were related to secreting cytokines IFN-γ and IL-17 of Th1 and Th17 cells, while Th17 cells might exert a positive effect on alveolar bone destruction.

Lateral cephalometric analysis of patients with maxillary alveolar protrusion and advanced periodontitis treated with immediate implants and cross-arch fixed prostheses

Objective: To investigate the changes of the lateral cephelometric landmarks of soft tissue and hard tissue of patients with maxillary alveolar protrusion and advanced periodontitis treated with immediate implants and cross-arch fixed prostheses. Methods: From January 2013 to October 2016, consecutive patients with advanced periodontitis and maxillary alveolar protrusion in need of immediate implants and cross-arch fixed prostheses were included in this study. All the patients were treated with provisional cross-arch fixed prostheses supported with 4 to 6 immediate implants after extraction of all the residual teeth and reduction of excessive alveolar bone. After 6 months, a final cross-arch fixed prosthesis was delivered. The lateral cephalometric landmarks of soft tissue and hard tissue at the time of pre-operation and final prosthesis delivery were analyzed. The change of patients' facial aesthetics was assessed using visual analogue scale (VAS). Results: Ten patients were included in the study. All the patients underwent full arch rehabilitation of both jaws supported by a total of 89 dental implants. In the maxillae, the average number of inserted implants were 4.5. The mean height of alveolar bone reduction was (6.3±1.8) mm. Both the distance of U1-NA (the upper incisor to nasion-A point line) and U1-PP (the upper incisor to palatal plane) were significantly reduced by (5.5±2.7) mm and (1.6±1.2) mm, respectively. The angle of U1-SN (between upper incisor to sella-nasion line) was reduced by 9.6°±8.1°palatally. The nasolabial angles were significantly increased by 10.5°±6.4°. Both the patients and dentists considered that the facial aesthetics was improved greatly after the treatment. Conclusions: With the reduction of excessive alveolar bone and the realignment of artificial teeth, the treatment of immediate implants and cross-arch fixed prostheses could improve the facial aesthetics of the patients with advanced periodontitis and maxillary alveolar protrusion.

Mucosal Perfusion Preservation by a Novel Shapeable Tissue Expander for Oral Reconstruction.

Background:There are few methods for expanding oral mucosa, and these often cause complications such as tissue necrosis and expander eruption. This study examines mucosal blood perfusion following insertion of a novel shapeable hydrogel tissue expander (HTE). The canine model used subgingival insertion of HTE following tooth extraction and alveolar bone reduction. The primary goal of this study was to gain understanding of epithelial perfusion and reparative responses of gingival mucosa during HTE expansion.Methods:Nine Beagle dogs underwent bilateral premolar maxillary and mandibular tooth extraction. Three to four months later, HTE-contoured inserts were implanted submucosally under the buccal surface of the alveolar ridge. After removal and following a 6- to 7-month period of healing, new HTE implants were inserted at the same sites. The area was assessed weekly for tissue perfusion and volume of expansion. Biopsies for histological analysis were performed at the time of expander removal.Results:Within 2 weeks following the second insertion, blood flow returned to baseline (defined as the values of perfusion measurements at the presurgery assessment) and remained normal until hydrogel full expansion and removal. Volume expansion analysis revealed that the hydrogel doubled in volume. Histological assessment showed no macrophage or inflammatory infiltration of the mucosa. No superficial fibrosis, decreased vascularity, or mucosal change was seen.Conclusion:Maintenance of adequate tissue perfusion is a clinically important aspect of tissue expander performance to reduce risk of device loss or injury to the patient, particularly for areas with a history of previous surgeries.

Peptide-induced de novo bone formation after tooth extraction prevents alveolar bone loss in a murine tooth extraction model

Tooth extraction causes bone resorption of the alveolar bone volume. Although recombinant human bone morphogenetic protein 2 (rhBMP-2) markedly promotes de novo bone formation after tooth extraction, the application of high-dose rhBMP-2 may induce side effects, such as swelling, seroma, and an increased cancer risk. Therefore, reduction of the necessary dose of rhBMP-2 which can still obtain sufficient bone mass is necessary by developing a new osteogenic reagent. Recently, we showed that the systemic administration of OP3-4 peptide, which was originally designed as a bone resorption inhibitor, had osteogenic ability both in vitro and in vivo. This study evaluated the ability of the local application of OP3-4 peptide to promote bone formation in a murine tooth extraction model with a very low-dose of BMP. The mandibular incisor was extracted from 10-week-old C57BL6/J male mice and a gelatin hydrogel containing rhBMP-2 with or without OP3-4 peptide (BMP/OP3-4) was applied to the socket of the incisor. Bone formation inside the socket was examined radiologically and histologically at 21 days after the extraction. The BMP/OP3-4-group showed significant bone formation inside the mandibular extraction socket compared to the gelatin-hydrogel-carrier-control group or rhBMP-2-applied group. The BMP/OP3-4-applied mice showed a lower reduction of alveolar bone and fewer osteoclast numbers, suggesting that the newly formed bone inside the socket may prevent resorption of the cortical bone around the extraction socket. Our data revealed that OP3-4 peptide promotes BMP-mediated bone formation inside the extraction socket of mandibular bone, resulting in preservation from the loss of alveolar bone.

Oral Symptoms and Bone Observations in Odonto-Hypophosphatasia

Hypophosphatasia (HPP) is an inherited skeletal disease caused by mutation of the gene encoding tissue non-specific alkaline phosphatase (TNSALP). Odonto-HPP is well known as the mildest of HPP. The manifestations involve only the teeth, such as premature primary teeth exfoliation caused by reduction of alveolar bone, enlarged dental pulp chamber, and dental defects. We report a case of a 9-years-old boy who developed HPP. He was observed from the primary dentition to the mixed dentition period. At initial presentation at our hospital, he had multiple premature exfoliation of primary teeth and reduction of the alveolar bone. HPP was suspected due to the low level of ALP activity in serum, his oral manifestation, and dental history. He was referred to a physician for the final diagnosis. Therefore his compound heterozygote mutations, c.1559 delT (T/delT) and c.407G > A (G/A), were found in TNSALP and he diagnosed with odonto-HPP. Even though these mutations were reported as being involved in odonto-HPP, his mineral densities tended to be lower than that of his age. It is therefore necessary to investigate the bone mineralization level in odonto-HPP without other bone symptoms. Moreover, ongoing enzyme-replacement therapy in odonto-HPP might improve dental abnormality and bone disorders.

A finite element study to determine the occurrence of abfraction and displacement due to various occlusal forces and with different alveolar bone height.

Background:Noncarious cervical lesions (NCCLs) are rarely described in the periodontal literature, perhaps because no direct link between NCCLs and periodontal lesions has been demonstrated.Aim:The aim of this study is to determine the stress and displacement produced in the tooth at different bone levels under different occlusal load using finite element model (FEM) study.Materials and Methods:Four FEMs of maxillary incisor were designed consisting of the tooth, pulp, periodontal ligament, and alveolar bone at the various level of bone height (25%, 50%, and 75%). Different occlusal load (5 kg, 15 kg, 24 kg, and 29 kg) at an angle of 50° to the long axis of the tooth was applied on the palatal surface at the level of middle third of the crown. All the models were assumed to be isotropic, linear and elastic, and the analysis was performed on a Pentium IV processor computer using the ANSYS software.Results:The maximum stress in the tooth was seen in the cervical region and to a greater extent at the apex for all models. The maximum tooth displacement for all the occlusal loads applied in this study was at the incisal edge with the minimum tooth displacement at the cervical third of the root which shifted apically with the reduction of alveolar bone support.Conclusion:The cumulative effect of increased stress and displacement at the cervical region of the tooth would result in abfraction as the age advances along with other wasting diseases.

Alveolar socket healing: what can we learn?

Tooth extraction induces a series of complex and integrated local changes within the investing hard and soft tissues. These local alterations arise in order to close the socket wound and to restore tissue homeostasis, and are referred to as '"socket healing". The aims of the present report were twofold: first, to describe the socket-healing process; and, second, to discuss what can be learned from the temporal sequence of healing events, in order to improve treatment outcomes. The socket-healing process may be divided into three sequential, and frequently overlapping, phases: inflammatory; proliferative; and modeling/remodeling. Several clinical and experimental studies have demonstrated that the socket-healing process promotes up to 50% reduction of the original ridge width, greater bone resorption at the buccal aspect than at the lingual/palatal counterpart and a larger amount of alveolar bone reduction in the molar region. In conclusion, tooth extraction, once a simple and straightforward surgical procedure, should be performed in the knowledge that ridge reduction will follow and that further clinical steps should be considered to compensate for this, when considering future options for tooth replacement.

Contour changes in human alveolar bone following tooth extraction of the maxillary central incisor.

The purpose of this study was to apply cone-beam computed tomography (CBCT) to observe contour changes in human alveolar bone after tooth extraction of the maxillary central incisor and to provide original morphological evidence for aesthetic implant treatment in the maxillary anterior area. Forty patients were recruited into the study. Each patient had two CBCT scans (CBCT I and CBCT II), one taken before and one taken three months after tooth extraction of maxillary central incisor (test tooth T). A fixed anatomic reference point was used to orient the starting axial slice of the two scans. On three CBCT I axial slices, which represented the deep, middle, and shallow layers of the socket, labial and palatal alveolar bone widths of T were measured. The number of sagittal slices from the start point to the pulp centre of T was recorded. On three CBCT II axial slices, the pulp centres of extracted T were oriented according to the number of moved sagittal slices recorded in CBCT I. Labial and palatal alveolar bone widths at the oriented sites were measured. On the CBCT I axial slice which represented the middle layer of the socket, sagittal slices were reconstructed. Relevant distances of T on the sagittal slice were measured, as were the alveolar bone width and tooth length of the opposite central incisor. On the CBCT II axial slice, which represented the middle layer of the socket, relevant distances recorded in CBCT I were transferred on the sagittal slice. The height reduction of alveolar bone on labial and palatal sides was measured, as were the alveolar bone width and tooth length of the opposite central incisor at the oriented site. Intraobserver reliability assessed by intraclass correlation coefficients (ICCs) was high. Paired sample t-tests were performed. The alveolar bone width and tooth length of the opposite central incisor showed no statistical differences (P<0.05). The labial alveolar bone widths of T at the deep, middle, and shallow layers all showed statistical differences. However, no palatal alveolar bone widths showed any statistical differences. The width reduction of alveolar bone was 1.2, 1.6, and 2.7 mm at the deep, middle, and shallow layers, respectively. The height reduction of alveolar bone on labial and palatal sides of T both showed statistical differences, which was 1.9 and 1.1 mm, respectively.

Verbetering van een gebitsprothese door middel van relining of rebasing

When the fit of a removable complete denture is diminished as a result of progressive alveolar bone reduction, relining or rebasing might be indicated. In clinical practice, a degree of confusion exists concerning the concepts relining, and rebasing. Relining is resurfacing the tissue side of a denture with a new material to fill the space which exists between the original denture contour and the altered tissue contour. Rebasing is resurfacing the fitting surface of a denture by replacing the entire denture base with new material, also to fill the space which exists between the original denture contour and the altered tissue contour. In particular, attention is given to 3 specific forms ofrelining and rebasing which serve to restore the maxillomandibular relationship, to extend effectively the palatal denture surface of the maxillary denture and to reline or rebase an implant-supported overdenture.

Induction of IL-10-producing CD4+ T-cells in Chronic Periodontitis

Precise immunological aspects of inflamed gingival mucosa remain to be elucidated in the murine experimental periodontitis model; therefore, we have characterized the mucosal immune cells in the inflamed gingiva of mice with alveolar bone reduction. Mice were orally infected with Porphyromonas gingivalis 15 times over 2 weeks. Gingival mononuclear cells (GMCs) were isolated from P. gingivalis- and sham-infected mice 1, 7, 15, and 30 days after the last infection. Although the greatest degree of periodontitis was seen in P. gingivalis-infected mice at 30 days after infection, the highest levels of IL-6 and TNF-α production were noted in the GMCs isolated 7 days after infection. Further, the frequency of RANKL+CD4+ T-cells in GMCs of inflamed gingiva peaked 15 days after infection. Importantly, the number of Foxp3+CD4+ CD25+ regulatory T (Treg)-cells was increased only in the experimental group 30 days after infection. Thus, intracellular cytokine analysis revealed an increased number of IL-10-producing CD4+ T-cells in inflamed gingiva when compared with the control group. These results suggest that there are potential roles for Treg cells during the chronic stage of periodontitis in the regulation of gingival inflammation and alveolar bone loss.

Effect of bone thickness on alveolar bone-height measurements from cone-beam computed tomography images

Cone-beam computed tomography (CBCT) has been used to assess alveolar bone changes after rapid palatal expansion. The purpose of this study was to investigate the accuracy of alveolar bone-height measurements from CBCT images with varied bone thicknesses and imaging resolutions. Eleven maxillary specimens from 6-month-old pigs were measured for alveolar bone height (distance between drilled reference holes and alveolar crests) at 6 locations with a digital caliper, followed by CBCT scanning at 0.4-mm and 0.25-mm voxel sizes. Buccal alveolar bone of these locations was then reduced approximately by 0.5 to 1.5 mm, followed by CBCT rescanning with the same voxel sizes. The CBCT images were measured by using 3-dimensional software to determine alveolar bone height and thickness in buccolingual slices by independent, blinded raters. The specimens were subsequently cut into buccolingual sections at reference-hole levels, and direct bone height and thickness were measured from these sections. Intrarater and interrater repeatability and the differences between CBCT and direct measurements were assessed. Excellent intrarater (intraclass correlations, r = 0.89-0.98) and good interrater (r = 0.64-0.90) repeatability values were found for alveolar bone-height measurements from the CBCT images. Before alveolar bone reduction, the thickness was much greater than the CBCT voxel size (0.4 mm), and bone-height measurements from the CBCT images were 0.5 to 1 mm more than the direct measurements (paired t tests, P <0.017 at most locations). After bone reduction, the thickness at the subcrest 1-mm level was near or below the CBCT voxel size (0.4 mm), and bone-height measurements from the CBCT images were 0.9 to 1.2 mm less than the direct measurements (paired t tests, P <0.017 at most locations). These measurement inaccuracies were substantially improved by decreasing the CBCT voxel size to 0.25 mm. Alveolar bone-height measurements from conventional clinical 0.4-mm voxel size CBCT images might overestimate alveolar bone-height loss associated with rapid palatal expansion.