Full Denture Research Articles

The Effects of the Expansion of Dental Care Coverage for the Elderly.

Expanding dental care coverage for the elderly is globally recommended but not widely implemented due to its high costs and intangible benefits. This study examined the impact of such an expansion in Korea using the imputation-based method proposed by Borusyak et al. We analyzed data from the Korea National Health and Nutrition Examination Survey (2007-2019) on dental service utilization and chewing ability among older adults. The policy resulted in a 13.5% increase in partial denture use and a 60.5% increase in dental implants among those aged 65 and above. These changes corresponded with reductions in severe chewing difficulty by 23.3% and 13.0%, respectively. No significant changes were observed in full denture use. The price elasticity of demand for partial dentures and dental implants was estimated to be -0.19 and -0.86, respectively. These findings underscore the critical role of affordability in enhancing the utilization of dental implants among the elderly and highlight the importance of appropriately expanding dental insurance coverage to improve oral health outcomes in this population.

Accuracy of measurements on CBCT-generated digital models using different exposure parameters (in vitro study).

Dental imaging comprises a wide range of techniques and modalities, each with different diagnostic features influenced by numerous parameters, all of which contribute to the precision and effectiveness of dental evaluations and treatments. This study examined the dimensional reproducibility of arch measurements from CBCT scans with different voxel sizes and exposure parameters compared to a reference model from Extra-oral scanners (EOS) and how these parameters affected digital matching and diagnostic image quality. A diagnostic observational study of arch dimensions, including inter-canine, inter-premolar, intermolar, arch width and arch length, was conducted on digital models (DMs) created from 65 CBCT scans of a full dentate epoxy maxillary model. The measurements obtained from EOS scans served as the control for the study. Normality was tested with the Shapiro-Wilk test, comparisons used the Kruskal-Wallis test with Bonferroni-adjusted pairwise comparisons for significant results, and data were analysed using IBM SPSS (Version 26.0), with significance set at p < .05. Significant deviations were revealed among study groups, with group I (smallest voxel size) consistently displaying the lowest values, mean (SD) deviation was reported as 0.01 (0.006) and group IV (lowest kV value) exhibiting the highest deviations, mean (SD) deviation of 0.16 (0.17). Combining a small voxel size (0.12 mm) with high milliampere (8 mA) and kilovoltage (90 kV) settings in CBCT ensured detailed anatomical visualization and accurate linear measurements, crucial for precise dental assessments, and emphasizing the necessity for strict control over CBCT parameters in dental applications.

Evaluating the Impact of Posterior Edentulism on Temporomandibular Disorder-Related Bruxism, Tinnitus, and Depression

Purpose: The impact of posterior edentulism on the management of temporomandibular disorders (TMD) remains unclear, with a paucity of studies examining the influence of posterior edentulism on TMD symptoms. The objective of this study is to investigate the relationship between posterior edentulism and bruxism, tinnitus, and depression in TMD patients and to compare treatment outcomes in two groups with and without posterior edentulism. Material and methods: In a quasi-experimental controlled trial, 26 patients with TMD participated in a six-week intervention, including manual therapy, massage, postural exercises and kinesio taping. The patients were divided into 13 in the posterior edentulous group and 13 in the full dentate group. The participants attended 12 physiotherapy sessions, twice a week, over six weeks. Outcome measures, including bruxism, tinnitus, joint clicking, Beck Depression Inventory, and cervical range of motion, were evaluated at baseline and the end of the six weeks. Results: The six-week physiotherapy program significantly improved bruxism, tinnitus, cervical range of motion, and depression (p

Comparative Evaluation of Speech Quality Before and After Functional Palatal Recontouring in Complete Dentures using Artificial Intelligence: A Study Protocol.

Introduction In the realm of dentistry, where precision and understanding of oral structures are paramount, the utilization of advanced technologies has revolutionized diagnostic and treatment methodologies. One such technology, palatography, holds significant importance in understanding the intricate dynamics of the oral cavity, particularly the interaction between the tongue and the palate during speech and swallowing. In the field of prosthodontics, achieving a successful outcome goes beyond simply restoring missing teeth. A well-designed denture or prosthesis should not only function properly but also consider factors like aesthetics, comfort, and speech intelligibility. Methods The speech quality analysis using artificial intelligence has been designed to assist in the palatal recontouring of complete dentures during the trial denture appointment and denture insertion. The study will be conducted on 12 completely edentulous patients, selected based on exclusion and inclusion criteria. Expected results The palatal recontouring assessment is expected to improve speech quality significantly. This could be incorporated into routine complete denture rehabilitation cases where the ease of technology can help enhance the phonetics of the prosthesis. Conclusions Patients undergoing full denture rehabilitation benefit greatly from phonetics. Taking this key factor into play through the use of advanced but readily available technology, palatography can be employed as a routine procedure for rehabilitation through complete dentures. There is definitely a learning curve involved while making it a routine procedure, but it is, nonetheless, a significant addition to holistic rehabilitation.

Wimpole Timings study.

Introduction Studies show that changes to dental incentive structures and treatment timings impact behaviour among UK general dental practitioners (GDP). Since 1980, the British Dental Association (BDA) has conducted panel inquiries to understand the time taken to complete dental treatments, the most recent of these being the 1999 Heathrow Timings study.Aims Given significant changes to the UK general dental service (GDS) since 1999, this research aims to gain a refreshed understanding of the time involved to complete clinical treatments in the UK and gain insight into working hours.Materials and methods This study adopted a mixed-method research design, adapted from the BDA's Heathrow Timings study. Averages for 34 adult and 12 children's treatments were found using an online survey and group discussion with 15 GDPs.Results Overall, GDPs worked 35.23 hours per week, at an hourly rate of £39.94. Comparison to the Heathrow study in 1999 shows an increase in time to deliver multiple treatments, including clinical examinations, root canals, extractions, composite fillings, porcelain veneers, acrylic full dentures and children's extractions.Conclusion Overall, this study provides a current and updated insight into dental treatment times performed by GDPs in the UK and highlights a decrease in working hours and real-term earnings of GDPs over the past 20 years.

Use of collapsible surgical templates in full dentures with immediate loading

Use of collapsible surgical templates in full dentures with immediate loading

한국 성인의 가철성의치 장착 여부 및 필요도와 범불안장애 관련성

Objectives: The purpose of this study was to investigate the relationship between removable dentures, need, and generalized anxiety disorder in Korean adults. Methods: Using data from the 8th National Health and Nutrition Examination Survey (2021), 4,362 adults aged 40 or older were surveyed using SPSS 21.0. Results: The average score of the subjects' general anxiety disorder was 1.80 out of 3. In the maxillary prosthesis state, general anxiety was perceived higher in the partial denture than no prosthesis. In the necessity of mandibular removability, it was confirmed that the general anxiety disorder was perceived higher in the full denture than in the partial denture. Conclusions: Efforts should be made to promote and prevent oral health so that it is not included in the subjects who use removable dentures and experience general anxiety disorder.

Mandibular Overdentures When Treating Failing Dentition With Immediate Prosthetic Loading.

Patients may present with failing mandibular dentition either involving the entire arch, partial arch that currently has a partial denture to replace the prior missing teeth or wearing a full denture. Finances may limit restoration of the arch with an All-on-X concept and the patient's goals are a stable prosthesis that does not move whenconcept and the patient's goals are a stable prosthesis that does not move when eating or speaking is the patient's expressed goal. Overdentures can fulfil that goal and provide a stable restored arch at a lower treatment cost than treatment with a fixed hybrid prosthesis. Traditionally, when these type cases have been treated, the remaining dentition has been extracted, depending on availability of bone, implants are placed. Those typically were left to osseointegrate and loaded several months later with a delayed loading approach. This requires relining the denture and the patient having a loose, non-stable prosthesis during that healing phase. An alternative approach utilizes immediate activation of the implants with overdenture attachments thus, providing an immediate stable retentive full arch mandibular removable prosthesis (overdenture) by immediate activation of overdenture attachments (ie.Locators) aids the patient in their goals without delays in treatment. This article will present two case examples of mandibular arches with failing dentition related to caries and periodontal issues and their treatment with immediate implant placement and loading with Locator attachments. Long-term follow-up of 1-year 8-months in one case and 33-months in the other case demonstrate crestal bone stability with this immediate overdenture loading protocol.

A systematic review on prosthodontic rehabilitation of hemimandibulectomy patients

To restore oral function after tumor excision, practitioners must undertake the enormous challenge of restoring hemimandibulectomy deficits. Depending on the type and extent of mandibular reconstruction (Cantor-Curtis classification), there are many prosthetic treatment options available for the rehabilitation of acquired hemimandibulectomy abnormalities. The objective of this systematic study is to evaluate the range of prosthodontic rehabilitation techniques in relation to the kind of repair and severity of mandibular surgical abnormalities. The databases incorporated for literature search were Google Scholar and Medline (PubMed). Relevant search terms for hemimandibulectomy and reconstruction with prosthetic rehabilitation were used. Two reviewers independently assessed the articles using eligibility criteria; published case reports and case series in the English language and depicting prosthodontic treatment modality of patients greater than 13 years were included. A total of 212 records were identified from the database search of which 29 duplicates were removed.The remaining articles were assessed for eligibility, and 50 articles (comprising 50 cases) were finally included in the study. This review identified a number of prosthetic options, including some novel prosthetic techniques, guiding flange, twin occlusion, palatal ramp, conventional to hybrid partial and complete dentures, and implant-supported prosthesis.The prosthetic options covered in this review included implant-supported prosthesis, guide flange, dual occlusion, palatal ramp, conventional, hybrid, and full dentures, as well as a few cutting-edge prosthetic techniques.As they plan and manage sequential therapy for hemimandibulectomy cases in their daily practice, practitioners and prosthodontists will find this helpful.

Evaluation of the accuracy of seven intraoral scanners for the full dentate and partially edentulous complete-arch mandibular casts: An in vitro comparison

Statement of problemIntraoral scanners (IOSs) are widely used in dentistry, providing high accuracy in short-range scanning. Nevertheless, when scanning the full dental arch, it remains a challenge. Furthermore, there is a lack of studies reporting the differences in scan accuracy between dental arches with large-span mucosal areas and fully dentate casts or optimal IOS selection for different dental statuses. PurposeThis study aimed to evaluate the accuracy and scanning time of different IOSs for full dentate (FD) and partially edentulous (PE) casts with missing teeth in the #34–#44 range and to determine the IOSs with the optimal clinical adaptability and scanning accuracy for different complete-arch casts. Material and methodsReference scans of two complete-arch (FD and PE) casts were obtained using a laboratory scanner (Ceramill Map 600). Subsequently, the same casts were scanned ten times each by seven IOSs (3Shape Trios 3, CS3600, Planmeca Emerald, iTero Element 5D, Medit i500, BAMBOO B1, and Shining Aoralscan 3), and the scanning time was recorded. The test data were superimposed on the reference scans for the selected areas, and three-dimensional deviations between the reference and test casts (trueness), and between test casts (precision) were determined using reverse engineering software (Geomagic Wrap). The dataset was analyzed using a two-factor analysis of variance with post-hoc Bonferroni tests. ResultsTwo-factor analysis of variance revealed significant differences in accuracy and scanning time for different casts (P < 0.001) and IOSs (P < 0.001). For the FD cast, the i500 (0.35 ± 0.11 mm trueness) and CS3600 (0.23 ± 0.12 mm precision) performed worse than the remaining scanners. For the PE cast, the BAMBOO B1(0.89 ± 0.58 mm trueness; 0.88 ± 0.48 mm precision) performed worse than the remaining scanners. There were no differences in the accuracy of scanning between the Element 5D and Emerald for both cast types. However, the scanning time differed significantly between the different IOSs (P < 0.001). Regardless of the cast type, the fastest and slowest scans were performed by the Trios3 and CS3600 scanners respectively. ConclusionsThe accuracy and scanning time differed between the different IOSs and types of complete-arch casts.

Clinical Longevity of Obturators in Patients with Jaw Defects: a Retrospective Cohort Study.

The primary objective of the present retrospective clinical study was to determine the survival time of obturators while analyzing possible influencing factors. This retrospective clinical cohort study analyzed the influence of various clinical factors on the survival probability of obturators and their follow-up outcomes using Kaplan‒Meier analysis. A total of 76 patients with 115 obturators were included in the study (47 men and 29 women, mean age 58.1 ± 18.1years). The mean observation time was 3.0 ± 4.5years (maximum 26.3years). A total of 40.9% (47) of all obturators observed had to be replaced. The survival rate after 5years was 79.5% for telescopic-crown-retained tooth-supported obturators, 86.9% for telescopic-crown-retained implant-supported obturators, 58.8% for removable full denture obturators, 22.1% for clasp-retained obturators and 0.0% for splints. The type of attachment, attendance at a regular follow-up and defect cause significantly influenced the survival of the obturators (p < .05). The findings obtained in this study support the recommendation of using implant-supported obturators. Telescopic-crown attachments, either tooth- or implant-supported, seem to be favorable in terms of survival time. Attendance at a strict follow-up program seems to have a major influence on the longevity of the obturators. The use of implant-supported obturators to cover permanent oral and maxillofacial defects is highly recommended. Additionally, the use of telescopic-crown attachments seems to be favorable in terms of survival time. Clasp-retained obturators and surgical splints should be used primarily for temporary restorations due to their shorter survival times.

Evaluation of effect on stability of implants with and without platelet rich fibrin using a resonance frequency analyzer - An in-vivo study

BackgroundAlthough the conventional replacement for lost teeth has been partial or full dentures, the need for a fixed, esthetic, and functional restoration makes dental implants a reliable alternative. AimTo evaluate the initial and final stability of platelet rich fibrin coated implants using resonance frequency analyzer. Methodology: Thirteen patients with two or more missing teeth were informed about the procedure, and a consent form was obtained after cone beam computer tomography evaluation. Blood was drawn from the anticubital area of the patient, which was centrifuged to obtain platelet-rich fibrin. In all, 26 implants were placed, among which 13 were platelet-rich fibrin-coated (test group) and 13 were without platelet-rich fibrin (control group), and implant stability quotient values were recorded. ResultsThe mean age of the patients was 34.4 (SD = 4.28). Majority of the patients were males (9; 69.2%) whereas there were only four (30.8%) female patients. When comparison between overall primary implant stability with and without PRF was done, the mean difference was 5.12 and this difference was not statistically significant (p = 0.221) whereas a statistically significant difference (p = 0.019) was found when comparison between overall secondary implant stability was done with and without PRF. The primary and secondary stability values for the control group were 69.18 ± 7.45 and 73.84 ± 8.21 respectively, and the primary and secondary stability values for the test group were 64.06 ± 12.66 and 81.49 ± 7.61 respectively, which showed statistically significant differences among the groups. The difference in these values signify that primary stability is more in control group whereas secondary stability is more in case group. This signifies that PRF enhances the stability of implant. ConclusionImplants coated with platelet-rich fibrin exhibited better osseointegration than implants without platelet-rich fibrin.

Evaluation of different taste sensations along with body mass index (BMI) in geriatric patients with and without complete dentures.

The purpose of this study was to investigate the effect of acrylic full removable dentures on the perception of four primary tastes (sweet, sour, salty, and bitter), as well as to determine if there is a correlation between changes in body mass index (BMI) and taste perception. A total of 60 patients who wore acrylic removable dentures and 60 controls were included in the study as a convenient sample. Sixteen solutions for basic tastes were prepared, and the patients were asked to identify the taste of each solution from the lowest concentration. Anthropometric measures, such as height and weight, were measured and recorded in an MS-Excel sheet. The data were analyzed using SPSS version 23. The results showed that patients with complete removable dentures had lower taste scores for sourness (P < 0.001) and sweetness (P < 0.001) compared to the control group. However, there was no significant difference in salt taste scores (P = 0.218) and bitterness (P = 0.002) between the two groups. Additionally, the study found a correlation between lower BMI values and higher taste scores among denture-wearing patients, indicating an inverse relationship between total taste scores and BMI. The study suggests that geriatric patients with complete dentures have reduced taste sensations compared to those without dentures which can have a negative impact on their nutritional status. Therefore, it is crucial to provide adequate nutritional support and dietary counseling for geriatric patients based on health policy to maintain their overall health and well-being.

Common Oral Manifestations in a Denture Wearer Patients with Suspected Diabetes Mellitus

Background. Acute pseudomembranous candidiasis or often called oral thrush is a disease in the oral cavity caused by the overgrowth of Candida albicans. Angular cheilitis is an inflammatory lesion on the corners of the mouth. The purpose of this case report is to document the oral manifestations in patients with suspected diabetes mellitus. Case Report. A 57-year-old woman came with complaints of a burning sensation throughout the mouth and lips and presented a white spot on her tongue with soreness in the past year. The patient has diabetes mellitus and regularly takes medication. Despite this, the patient still has experienced classical signs of diabetes mellitus which are polyphagia, polydipsia, and polyuria. Intraorally the burning sensations were related to the full denture continuous wearness and were diagnosed as acute pseudomembranous candidiasis and angular cheilitis. The treatment given to this patient was symptomatic therapy in the form of Aloclair Plus mouthwash, causative therapy in the form of Nystatin oral suspension and referral to an internist to further examine the condition of diabetes mellitus, and supportive therapy in the form of lanolin and vaseline. Treatment ends with the provision of communication, instruction, and education.

A case report of improving masticatory dysfunction by full denture and implants for multiple missing teeth

A case report of improving masticatory dysfunction by full denture and implants for multiple missing teeth

РОЛЬ ЧАСТОТНО- РЕЗОНАНСНОГО АНАЛИЗА В ИССЛЕДОВАНИИ ДЕНТАЛЬНЫХ ИМПЛАНТАТОВ, УСТАНОВЛЕННЫХ В РЕКОНСТРУИРОВАННЫЕ АЛЬВЕОЛЯРНЫЕ ОТРОСТКИ С НЕБОЛЬШИМ ОБЪЕМОМ КОСТИ ЧЕЛЮСТЕЙ

The use of dental implants being the intraosseous artificial fixtures is often required for orthopedic rehabilitation of completely edentulous patients; for their placement, adequate amount of bone tissue is needed, which in many cases is insufficient due to physiological bone loss, long-term wearing of full dentures, the duration of edentulism and complex clinical situations caused by maxillofacial injuries or general somatic diseases. Implant placement in the above situations requires timely preparation of deficient alveolar ridge by means of osteoplastic surgery. In its turn, the newly formed regenerated bone by its histological, physicomechanical and structural-functional properties can only approach the recipient bone tissue; therefore, the issue of implant osseointegration and its functional loading in regenerated bone remains debatable. This research uses the method of frequency-resonance analysis showing implant stability coefficient numerically equal to the ISQ (Implant stability Quotient) values and reflecting the percentage of the osseointegration area of the intraosseous part of the implant. The results of research obtained by means of frequency-resonance analysis have proved that with the timely start of implant usage and adequate functional loading, ISQ values increase, that is, increases the osseointegration area along the interface of the intraosseous part of the implant placed in regenerated bone. Comparative results of research reflecting ISQ values in 12 months after implant placement in bone augmented using various forms of autogenous bonegrafts, have been presented; therefore, a conclusion can be made that there is a direct relationship between osseointegration under conditions of functional chewing load and the shape and size of autogenous bonegrafts.

Advantages of Additive Manufacturing for Complete Removable Dentures

The purpose of this review is to examine the existing body of research regarding complete 3D-printed dentures. This examination will cover new biomaterials, methods of creation, workflow, how well they work in clinical settings, and the contentment of patients using them. The methodology involved implementing a search plan, establishing criteria for inclusion and exclusion, and picking out relevant studies. Four reviewers conducted separate searches on PubMed, Scopus, and Embase databases to collect articles released from 2002 to 2023. From the electronic database, a sum of 116 headings was acquired, and after implementing exclusion criteria, 28 articles were pinpointed relating to technology for creating full dentures through printing. Present advancements and progress in digital dentistry have effectively enabled the production of removable dental prostheses through CAD/CAM technologies.

Perilaku pembersihan gigi tiruan lengkap pada Lansia panti werdha hana

Background: Behavior in cleaning full denture in the elderly has an important role in the success of complete denture treatment. This behaviour is an important thing so that patients can maintain the cleanliness of full denture and the health of their oral cavity. This study aims to determine the full denture cleaning behavior in the elderly. Methods: This type of research was descriptive observational with a cross-sectional design conducted on 32 elderly people in Hana Nursing Home, Pamulang, South Tangerang. The behavior of the elderly is measured through a questionnaire that has been provided previously. Results:The results of the descriptive statistical test showed that in general the behavior of cleaning of the elderly at the Hana Nursing Home had good results (46.9%). This good behavior is obtained based on good knowledge (59.4%), fairly good attitude (56.3%), and fairly good actions (53.1%). Based on gender grouping, it was obtained by the elderly group of men having full denture cleaning behavior which entered into a fairly good category (50%). Whereas the elderly woman in the Hannah Nursing Home has cleaning behavior that is included in the good category (50%). Based on age grouping, it can be seen that full denture cleaning behavior is good for the eldery age group (60-74 years), whereas in the old age group (75-90 years) and very old age group (&gt; 90 years) has a cleaning behavior is in fairly good category. Conclusion:The behavior of cleaning the full denture influenced by the knowledge, attitudes and actions taken by the elderly full denture users.

Identification of Candida Albicans Infection on Denture Wearing According to the Sex and Type of Denture Base Materials

Background: Oral Candidiasis is a wide opportunistic infection of the mouth due to an overgrowth of Candida species, the most being Candida albicans. Its harmless commensally organism inhabiting the mouth, but it will change into a pathogen, invade tissue, and cause acute and chronic diseases. The predisposing factor for infection with Candida was dentures in about sixty-five percentages of older peoples who are wearing full upper dentures. Objective: This research aims to determine the sex distribution of fungal infection in corresponding with fungal infection among groups (acrylic and metal denture base). Patients &amp;Methods: Sixty-eight patients attend the private dental clinic were subjected to usual dental treatment. They were divided into two groups: group 1: included 43 (24 females and 19 males) with acrylic denture base wearers. As well as, group 2: metal denture base wearers in 25 (10 females and 15 males). Questionnaire Paper to determine demographic data include, if patient take any fungal or antibiotic or not (treated and non-treated) and would obtain from the patients by including sex, age, and nocturnal wear. Result: The results in this study found that the prime etiology of Candida growth was the prosthesis materials itself. Sixty-five percent of the wearers of dentures showed Candida growth, while thirty-five percent of patients who had their dentitions showed Candida growth that the appliances are the dominant etiological factors in the growth of Candida other local factors should be considered.

Morphologic alterations in the mucosa of the denture site in patients with full removable dentures from acrylic plastics

Relevance. Currently, many new agents have appeared on the market for users of removable dentures to improve adhesion, i.e. fixation and stabilization of dentures. It is important to evaluate the effect of such agents on the denture bed mucosa.Objective. Morphological substantiation of the effectiveness of the use of adhesive cream for fixation of prostheses Asepta Рarodontalu patients with removable dentures made of acrylic plastic.Materials and methods. The study involved 49 patients (12 men and 37 women) of elderly age (62–75 years) who suffered complete loss of teeth on both jaws. All patients were divided into 3 study groups: 1 (control) group, who had previously refused to have full removable acrylic dentures made for them; 2 (comparison) group, patients to whom removable acrylic dentures were made and who did not use any means to improvetheir fixation; 3 (main) group, patients to whom full removable acrylic dentures were made and who during the adaptation period and subsequently for a year used a domestic adhesive cream for fixation; 3 (main) group, patients to whom full removable acrylic dentures were made. In order to solve the realization of the set goal of the study, a number of clinical and histological studies with the use of immunohistochemical method were carried out, outpatient charts of dental patients were analyzed.Results. It was found that dystrophic and chronic inflammatory changes in the soft tissues of the denture bed were most pronounced in the case of using dentures without means to improve their fixation. At use of domestic adhesive cream for fixation of dentures Asepta Рarodontal the process of keratinization of the oral mucous membrane epithelium was minimal, there was no fibrosis of the own lamina of the mucous membrane, scattered infiltration was less expressed than in people not using acrylic dentures or using them without adhesive means, and was represented at the expense of lymphocytes, single neutrophilic granulocytes on the background of single leukostases. The immunohistochemical study showed that T-lymphocytes and mast cells were predominant in the preparations of group 2 patients, and they appeared in the preparations of this group of patients comparatively more than in the 1st control and 3rd main groups of the study, which confirmed the presence of the most pronounced chronic inflammatory infiltration in group 2 patients.Conclusion. The most optimal condition of the denture bed mucosa was observed in patients who used removable acrylic dentures for a year and simultaneously applied an adhesive agent for their fixation (domestic adhesive cream for denture fixation Asepta Рarodontal). It is obviously connected with the protection of the mucous membrane of the prosthetic bed by the adhesive cream from the mechanical impact of a dense acrylic plastic prosthesis, as well as with the reduction of contact with food products aggressive in temperature and structure.