Effect of self-reported clinician experience level on perceptions of the relative rankings of risk factors for biological complications with dental implant therapy.

STATEMENT OF PROBLEM: The effect of clinician experience on the perception of risks for biological complications associated with dental implant therapy is unknown. PURPOSE: The purpose of this study was to determine whether clinician experience levels, as assessed by the number of implants placed and/or restored, as well as by type of clinical experience (restorative/prosthodontic and/or surgical), influence the perception of risk for biological complications with dental implant therapy. MATERIAL AND METHODS: A 10-item survey instrument was developed that asked participants from a convenience sample to rank different risk factors for peri-implant complications in the areas of patient history, clinical findings, and clinician choices and postimplant placement findings. Information about participant experience (number of implants placed and restored and type of experience) was also captured. The Kruskal-Wallis and Mann-Whitney U test statistical analyses were performed to determine the degree, if any, to which the level of clinician experience influenced risk factor rankings (α=.05). RESULTS: Clinicians with more experience viewed the use of selective serotonin reuptake inhibitor (SSRI) medications and clinician inexperience as more important risk factors than did less experienced clinicians. Clinicians with less experience viewed treated moderate or severe chronic periodontitis and thin tissue biotype as more important risk factors than did more experienced clinicians. Clinicians with predominantly surgical experience viewed a heavy plaque index as a more important risk factor than clinicians with predominantly restorative experience. CONCLUSIONS: The data indicate that the level of clinical experience influences how risk factors associated with biological complications of dental implant therapy are viewed by clinicians.

Active Surveillance of Root Caries in Vivo with CP-OCT.

The active surveillance of root caries lesions to monitor potential remineralization or decay progression is challenging for the clinician, due to unreliable diagnostic information. The conventional visual and tactile methods for assessing the lesion activity are not reliable, and the clinician is often unable to determine if the lesion is progressing or has been arrested. An important marker of an arrested lesion is a highly mineralized transparent surface zone (TSL) that forms when the mineral is deposited in the outer layer of the lesion. The purpose of this study was to determine if cross-polarization optical coherence tomography (CP-OCT) could be used to detect changes in the lesion severity and activity during active monitoring. In total, 18 subjects with 22 suspected active root caries lesions were evaluated using CP-OCT at the baseline, 3 months, and 6 months. All subjects were instructed to use a high fluoride dentifrice at the baseline. The results showed that CP-OCT was able to discriminate the active from the arrested lesions by identifying the presence of a TSL on arrested lesions. The results also indicated that the mean TSL thickness increased significantly (p < 0.05) for the nine lesion areas. In addition, CP-OCT was able to show the progression of demineralization, erosion, and changes in gingival contours in scanned areas. CP-OCT was valuable for monitoring the activity and severity of root caries lesions in vivo. CP-OCT can be used to assess the activity of root caries lesions at a single time point by detecting the presence of a TSL at the lesion surface indicative of the lesion arrest.

The significance of vertical platform discrepancies and splinting on marginal bone levels for adjacent dental implants.

OBJECTIVE: The aim of this retrospective study was to investigate the influence of vertical platform discrepancies for splinted and non-splinted adjacent implants on radiographic marginal bone loss (RMBL). METHODS: Data from January 2000 to February 2021 were collected from the electronic charts of 156 patients with 337 implants at the UCSF School of Dentistry. Five different implant restoration categories were evaluated for radiographic evidence of proximal RMBL. Patients with (1) two adjacent single crowns, (2) two adjacent splinted crowns, (3) three-unit bridges supported by two implants, (4) three adjacent single crowns, and (5) three adjacent splinted crowns. Inclusion required baseline radiograph taken at the time of prosthesis delivery or final impression, and follow-up radiographs at least 12 months after restorations have been in function. Measurements assessed included vertical distance between adjacent implant platforms and proximal RMBL around implants. Odds ratios (ORs) and 95% confidence interval (95% CI) of implants with ≥1 mm RMBL between different type of restorations were calculated. RESULTS: In general, prostheses supported by splinted adjacent implants demonstrated a significant association with the presence of ≥1 mm RMBL (OR = 2.55, 95% CI = 1.17-5.17, p = 0.018) when compared to prostheses supported by non-splinted adjacent implants. In addition, prostheses with a vertical platform discrepancy ≥0.5 mm demonstrated a significant association with the presence of ≥1 mm RMBL (OR = 4.30, 95% CI = 1.85 to 10.01, p = 0.007) when compared to prostheses with a vertical platform discrepancy <0.5 mm. When adjacent implants had ≥0.5 mm vertical platform discrepancy, the majority (66.67%) of three splinted adjacent crowns had at least one implant with ≥1 mm RMBL. This was followed by two splinted adjacent crowns (58.97%), three-unit bridge (25.93%), two single adjacent crowns (24.24%), and three single adjacent crowns (18.18%). When adjacent implants had ≥1 mm vertical platform discrepancy, there was an increased percentage of implants with ≥1 mm RMBL. The restorative design associated with the highest percent of implants with bone loss was three splinted adjacent crowns (70%), two splinted adjacent crowns (61.11%), three single adjacent crowns (40%), and three-unit bridge and two single adjacent implants (21.05%). Three splinted adjacent crowns were significantly associated with ≥1 mm RMBL when compared to three-unit bridge (OR 6.56, 95% CI 1.59-27.07). Similarly, two splinted crowns were significantly associated with ≥1 mm RMBL when compared to two single crowns (OR = 2.50, 95% CI = 1.08-5.79). CONCLUSION: Two or three adjacent implants placed with a vertical platform discrepancy, when splinted together, are associated with higherincidence of ≥1 mm RMBL than non-splinted restorations.

Influence of clinician gender, age, and geographic work location on the relative rankings of risk factors for biological complications with dental implant therapy.

STATEMENT OF PROBLEM: Clinician perceptions of risk factors influencing biologic complications with dental implants are poorly understood but are relevant to how clinicians manage conversations with patients seeking dental implant therapy. PURPOSE: The purpose of this clinician survey was to assess the relative ranking of biologic risk factors with dental implants identified via the history, clinical examination, and clinical decisions and postimplant placement findings. MATERIALS AND METHODS: A 10-item survey instrument was tested, refined, and distributed to past participants of the Future Leaders in Prosthodontics (FLIP) workshop series asking for their opinion on the relative ranking of commonly identified risk factors in the areas of patient history, clinical examination, and clinical decisions and postimplant placement findings. Descriptive statistics and frequency tables were developed to identify age groupings, geographic work location, and gender. Group differences with respect to risk factor rankings were identified by using Kruskal-Wallis H tests, and, if significant, paired comparisons were conducted using the Mann-Whitney U test with adjustments for Type I error (α=.05). RESULTS: Significant differences were found by gender, age, and geographic work location. Women viewed "implant placement in site of previous implant loss" (P=.013) and "treated moderate or severe chronic periodontitis" (P=.021) as having significantly greater relative importance than did men, yet men ranked "implant position closer than 1.5 mm from adjacent tooth" (P=.023), "currently using selective serotonin reuptake inhibitor drugs (SSRI)" (P=.001), and "heavy plaque index (PI>50%)" (P=.023) as having significantly greater relative importance than did women. Significant differences were found by geographic work location of practice with respondents from Australasia viewing "treatment plan includes prostheses that limit access for cleaning resulting in an increase in bacterial load" as having greater relative importance than did respondents from Africa (P<.001) and from South America (P<.001). Respondents from South America viewed "implant lacks 2.0 mm of attached tissue around implants" as having greater relative importance than did respondents from Australasia (P<.002) or Asia (P<.001). CONCLUSIONS: Clinicians viewed the relative importance of risk factors for biologic complications with dental implants differently, and those differences varied by clinicians' age, gender, and geographic location of practice.

The Pattern of Tooth Loss for Periodontally Favorable Teeth: A Retrospective Study.

To retrospectively analyze local and systemic factors that resulted in the short-term tooth loss of teeth that were previously assigned a favorable prognosis in patients who were seen and treated over an observational five-year period. This retrospective study included the records of patients who had a minimum of two dental exams at least twelve months apart over a 5-year period. This study investigated extracted teeth with an initially favorable periodontal prognosis that were then divided into one of four categories based on the reason for extraction: caries, periodontal disease, endodontic reasons, or fracture. Patient- and tooth-related factors associated with the extracted teeth were recorded: crown-to-root ratio, initial pocket depth, initial periodontal diagnosis, maintenance interval, presence of existing restoration, furcation involvement, and systemic conditions. Data analysis was performed using a linear mixed model. A total of 50 patients with 111 teeth met the inclusion criteria for this study. A higher odds ratio (OR) for tooth loss due to caries, endodontic reasons, and fracture were found in teeth with a history of root canal treatment with an OR of 3.61, 3.86, and 2.52, respectively. For tooth loss due to periodontal disease, higher ORs were found in patients who were on anti-depressants (OR = 4.28) and patients who had an initial diagnosis of Stage III/IV periodontitis (OR = 2.66). In addition, teeth with initial probing depths ≥5 mm (OR = 4.32) and with furcation involvement (OR = 1.93) showed a higher OR for tooth loss due to periodontal disease. Within the limitations of this study, previously root-canal-treated teeth present a higher OR for early loss due to caries, recurrent endodontic lesions, or fracture. In addition, patients with anti-depressant medication use, sporadic maintenance, initial probing depths ≥5 mm, and furcation involvement represent a significantly higher OR of tooth loss due to periodontal disease even for initially favorable teeth.

A commentary on strategic extraction.

BACKGROUND: Advancements in strategies to maintain compromised teeth combined with a greater understanding of risks associated with dental implants invite a reassessment of the benefits of strategic extraction of a tooth with a questionable prognosis or of limited strategic value. METHODS: Evidence of the management of compromised teeth and decision making for strategic extraction was reviewed. Additionally, the risks for peri-implantitis were evaluated from the perspective of patient centric, biologic, and biomechanical complications. RESULTS: Recent clinical innovations support a more predictable maintenance of compromised dentition, and the clinical literature provides evidence of the risks associated with dental implants. CONCLUSIONS: Because of the improvements in dental management of compromised dentition, strategic extraction should be deferred, whenever possible, to avoid complications associated with peri-implantitis.

Treatment planning considerations in the older adult with periodontal disease.

Periodontal health in the elderly is influenced by numerous factors, including systemic conditions, patient compliance, age-associated changes, and restorative procedures. The numerous comorbidities seen in the elderly necessitate individualized approaches for treatment planning. In this paper, we review how age, comorbidities, oral hygiene, and restorative dental procedures collectively influence the treatment and management of the periodontium in the elderly. The elderly population is predicted to double in 30 years, which will have an economic impact the dental profession needs to plan for. Preventative and noninvasive treatment, supportive periodontal therapy, and patient-specific maintenance plans are imperative to maintaining oral health in the older population. Multiple coexisting changes, including xerostomia, altered wound healing, altered bone physiology, altered microbiome, and diminished plaque control, can add complexity to periodontal management. Considerations of the patient's general health, the selected periodontal treatment plan, and the selected completed restorative procedures need to be considered. The influence of caries, fixed prosthodontics, partial dentures, shortened dental arch, and implant therapy can have unintended impacts on periodontal health in the elderly. Adverse periodontal outcomes in the elderly can be minimized by carefully assessing the patient's medical history, impact of medications, functional needs, properly finishing and contouring restorations to avoid plaque accumulation, and designing restorations to allow access for hygiene. Partial dentures can be a source of plaque accumulation leading to periodontal disease, caries, and recession around abutment teeth. A shortened dental arch should be considered as a functional and cost-effective alternative to partial dentures. With dental implants, the patient's tissue phenotype, keratinized tissue quantity, risk of peri-implantitis, and patient access for maintaining adequate oral hygiene are all important to consider. Implant risk-assessment tools show promise by providing a systematic approach for early diagnosis to avoid future complications.

Acute-Onset Achilles Tendon Pain and Swelling Treated with an Amniotic Fluid-Derived Allograft: A Case Study.

BACKGROUND: Tendinopathies are common musculoskeletal disorders that often develop because of chronic loading and failed healing. Tendinopathy related to systemic inflammation has been less extensively examined. Furthermore, although the use of biological agents to treat tendinopathies continues to gain popularity, the use of amniotic fluid-derived allografts in outpatient settings to resolve tendinopathies requires further evaluation. METHODS: The focus of this case report is a 25-year-old man who presented for a second opinion, having been diagnosed with Haglund deformity and Achilles tendinopathy. At the time of presentation, he complained of 10 of 10 pain to the right Achilles tendon. He was treating the injury conservatively with intermittent use of a controlled ankle motion boot and working with physiotherapy for approximately 5 months before presentation. Diagnostic ultrasound along with magnetic resonance imaging indicated distal thickening of the Achilles tendon, substantial fluid and edema in the Kager fat pad, and retrocalcaneal erosions with bursitis. Conservative management did not resolve the symptoms. As an alternative to surgery, the patient elected to undergo an Achilles tendon injection of an amniotic fluid-derived allograft. Before and after the initial injection, a microdialysis catheter was inserted into the Achilles peritendinous space to sample local levels of extracellular matrix enzymes and growth factors important for tendon remodeling. The patient received considerable relief with the initial injection, but did not return to full strength. Over the subsequent 8 weeks, the patient was followed closely and was able to return to daily activities with minimal pain. He was not able to return to a more active lifestyle without further Achilles pain, so a second amniotic fluid-derived allograft injection was performed 8 weeks after the initial injection. RESULTS: Injection of the initial allograft resulted in significant improvement, but not complete resolution of pain and swelling. Microdialysis findings suggested a reduction in peritendinous levels of the cytokine interlukin-6 in addition to changes in extracellular matrix regulatory enzymes. After 8 weeks of additional conservative therapy and a second injection, no further improvement in pain was noted. CONCLUSIONS: Based on the clinical improvement of symptoms in this individual and the changes seen with microdialysis methodology, the authors find the use of amniotic fluid-derived allograft injection for treatment of Achilles pain in this patient to be a viable treatment. Additional comorbidities of systemic inflammatory polyarthritis and possible seronegative disease were addressed after rheumatology consultation with a variety of medications that provided the patient additional relief of his symptoms. The patient ultimately moved and was lost to further follow-up.

The interrelationship between confidence and correctness in a multiple-choice assessment: pointing out misconceptions and assuring valuable questions.

INTRODUCTION: The aim of this study was to better understand the interfaces of being correct or incorrect and confident or unconfident; aiming to point out misconceptions and assure valuable questions. METHODS: This cross-sectional study was conducted using a convenience sample of second-year dental students (n = 29) attending a preclinical endodontics course. Students answered 20 multiple-choice questions ("basic" or "moderate" level) on endodontics, all of which were followed by one confidence question (scale). Our two research questions were: (1) How was the students' performance, considering correctness, misconceptions, and level of confidence? (2) Were the questions valuable, appropriate and friendly, and which ones led to misconceptions? Four situations arouse from the interrelationship between question correctness and confidence level: (1st) correct and confident, (2nd) correct and unconfident, (3rd) incorrect and confident (misconception) and (4th) incorrect and unconfident. Statistical analysis (α = 5%) considered the interaction between (a) students' performance with misconceptions and confidence; (b) question's difficulty with correctness and confidence; and (c) misconceptions with clinical and negative questions. RESULTS: Students had 92.5% of correctness and 84.6% of confidence level. Nine students were responsible for the 12 misconceptions. Students who had more misconceptions had lower correctness (P < 0.001). High achieving students had low confidence in their incorrect responses (P = 0.047). 'Moderate' questions had more incorrectness (P < 0.05) and less confidence (P = 0.02) than 'basic'. All questions were considered valuable [for example, the ones that presented images or required a mental picture of a clinical scenario, since they induced less misconception (P = 0.007)]. There was no difference in misconceptions between negative questions and other questions (P = 0.96). CONCLUSION: Preclinical endodontic students were highly correct and very confident in their responses. Students who had more misconceptions had also the lowest performance in the assessment. Questions were valuable; but some will worth further improvement for the future. A multiple-choice assessment, when combined with confidence questions, provided helpful information regarding misconceptions and questions value.

Use of mind maps in dental education: An activity performed in a preclinical endodontic course.

PURPOSE/OBJECTIVES: (1) to assess the ability of dental students to use mind maps to express the relationships of endodontic theory and technique; (2) to explore features illustrated from the highest- and lowest-graded mind maps; and (3) to evaluate improvements in successive mind maps from the same student. METHODS: A total of 31 second-year students were asked to configure a mind map on root canal cleaning-shaping and then 18 weeks later develop a second mind map on root canal obturation. Faculty visually analyzed the mind maps using a qualitative approach: a multilayered process of thematic analysis. Codes and themes were generated to investigate if students were able to express appropriate and evidence-based ideas on the topics (accuracy of relationships and depth of information presented). Two of the highest- and 2 of the lowest-graded mind maps for each activity were directly compared. Improvement by the same student from the first to second mind map was also evaluated based on trend/style and creativity. RESULTS: The majority of the students accurately expressed the scientific basis for root canal cleaning-shaping and obturation. The highest-graded mind maps displayed the biomedical and humanistic conceptions of critical thinking. In comparing the second mind map to the first, nearly 50% of the students incorporated more detail and artistic expression in the second map. CONCLUSIONS: using mind maps in dental education can benefit students with different learning styles and help the instructor to identify the level of conceptualization that the student had developed about a topic.

Dental Hygienists' Knowledge Regarding Dental Implant Maintenance Care: A national survey.

Purpose: Dental implants are now considered the standard of care for supporting dental restorations in edentulous areas. The purpose of this study was to explore the attitudes and practices of dental hygienists in the United States regarding dental implant assessment and maintenance care.Methods: A 34-item quantitative survey was developed and distributed nationally to a randomly selected sample of 10,000 dental hygienists from the American Dental Hygienists' Association (ADHA) email database. Responses were collected and analyzed via an online software program using frequency distributions for categorical variables.Results: A total of 2,018 dental hygienists participated for a response rate of 21%. The majority of respondents (98%) provided care to patients with dental implants. While the majority of respondents reported routinely assessing patients for bleeding/exudate, mobility, plaque/calculus, and tissue color around implants, 34% rarely/never checked for cement around implants, 31% rarely/never probed, and 54% rarely/never checked the occlusion. Nearly half of the respondents (44%) reported that they were unable to remove plaque as effectively from dental implants as from natural teeth. A majority (60%) reported using plastic/resin scalers, however only 7% of those who use plastic/resin scalers felt they were effective. While only 5% reported using air-polishers, 71% of the users felt they were effective. An oral irrigator was the most commonly recommended self-care hygiene aid for patients with implants and continuing education courses were the primary source of implant-related knowledge among respondents.Conclusion: The wide variation in implant-related assessment and maintenance care practices among dental hygiene respondents indicates a need for greater emphasis on evidence-based practices in dental hygiene curricula and in continuing education to ensure optimal care for patients with dental implants.

SWIR, Thermal and CP-OCT imaging probes for the in vivo assessment of the activity of root caries lesions.

New imaging technologies are needed for the clinical assessment of lesions on root surfaces. It is not sufficient to simply detect caries lesions; methods are needed to assess lesion depth, structural composition and activity to determine if chemical intervention has the potential to be effective and if remineralization has occurred. Lesions were monitored using CP-OCT during lesion dehydration to assess the lesion structure and any shrinkage. Thermal imaging at 6-10 µm wavelengths and short wavelength-IR imaging at 1450-1750-nm were used to monitor thermal emission during lesion dehydration to assess lesion activity. Imaging probes were custom fabricated for clinical use. We present the first clinical results of a small feasibility study employing CP-OCT, thermal and SWIR imaging to assess lesion activity in vivo on thirty test subjects with suspected root caries lesions.

Image-Guided Ablation of Dental Calculus From Root Surfaces Using a DPSS Er:YAG Laser.

BACKGROUND AND OBJECTIVES: Recent studies have demonstrated that near-infrared (IR) imaging can be used to acquire high-contrast images of root caries and calculus on the root surfaces of extracted teeth at wavelengths longer than 1450 nm. The purpose of this study was to determine if image-guided laser ablation can be used to selectively remove calculus from tooth surfaces with minimal damage to the underlying sound cementum and dentin. MATERIALS AND METHODS: In this study, sequential near-IR images at 1500-1700 nm were used to guide a diode-pumped (DPSS) Er:YAG laser for the removal of calculus from the root surfaces of 10 extracted teeth. The selectivity of removal was assessed using digital microscopy, optical coherence tomography, and surface profilometry. RESULTS: Calculus was removed rapidly with minimal damage to the underlying sound cementum and dentin. Image-guided ablation achieved high-selectivity, the mean volume of calculus removal was more than 27 times higher than the mean loss of cementum. CONCLUSIONS: We have demonstrated that near-IR image-guided laser ablation can be used for the selective removal of calculus from root surfaces ex vivo. Additionally, we have demonstrated that a diode-pumped solid-state Er:YAG laser is well suited for selective removal. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

The significance of surgically modifying soft tissue phenotype around fixed dental prostheses: An American Academy of Periodontology best evidence review.

BACKGROUND: This systematic review endeavored to investigate the effect of soft tissue phenotype modification therapy (PhMT-s) at sites with a tooth or an implant supported fixed dental prosthesis. METHODS: A comprehensive literature search was conducted by two independent examiners to identify relevant studies reporting differences in clinical, esthetic, or radiographic outcomes of interest between sites underwent PhMT-s and sites that remained untreated. Risk of bias assessment was calculated for all included studies. Meta-analyses involving endpoints of interest were performed when feasible. RESULTS: No controlled studies pertaining to tooth sites were identified. A total of six articles reporting on the outcomes of buccal soft tissue phenotype modification around implants were selected, of which, five were included in the meta-analyses. Quantitative analyses showed a weighted mean difference (WMD) of 0.98 mm (95% CI = 0.25 to 1.72 mm, P = 0.009) for change of tissue thickness; a WMD of -4.87% (95% CI = -34.27 to 24.53%, P = 0.75) for bleeding on probing (BOP); a WMD of 0.36 mm (95% CI = 0.12 to 0.59 mm, P = 0.003) for mucosal recession (MR); a WMD of 0.13 mm (95% CI = -0.11 to 0.36 mm, P = 0.30 for probing depth (PD); a WMD of 1.08 (95% CI = -0.39 to 2.55, P = 0.15) for pink esthetic score (PES), and a WMD of 0.40 mm (95% CI = -0.34 to 1.14 mm, P = 0.28) for marginal bone loss (MBL). CONCLUSIONS: Surgical modification of peri-implant soft tissue phenotype via PhMT-s may decrease the amount of MR. Future clinical trials are needed to warrant the clinical benefits of modifying soft tissue phenotype around tooth-supported restorations.

Effect of 0.2% peracetic acid disinfection on the horizontal dimension of implant framework indexed with two autopolymerized acrylic resins.

BACKGROUND: To minimize misfit between prosthesis and implant, the welding of the implant fixed partial denture (IFPD) framework is recommended and autopolymerized acrylic resin (AR) is the material of choice for the indexing process. As for any prosthetic device that comes into contact with saliva and blood in the oral cavity, IFPD indexed with AR must be disinfected before sending to the laboratory. However, disinfection procedures are often neglected for fear of shrinkage or distortion caused by a dimensional change of the acrylic resin. Peracetic acid is a high-level disinfectant agent at low concentrations and immersion time, with no reported toxic residues, and it is not inactivated in the presence of organic matter when compared to other disinfectants. This study aimed to evaluate the influence of 0.2% peracetic acid disinfectant solution after different storage media and times on the horizontal dimension of IFPD frameworks indexed with AR. MATERIAL AND METHODS: IFPD frameworks were indexed with two AR: group 1 Duralay and group 2 Pattern Resin LS. Each group was further divided into five subgroups according to disinfection procedure and storage medium: no disinfection and dry storage, no disinfection and water storage, 0.2% peracetic acid disinfection and water storage, 0.2% peracetic acid disinfection and peracetic acid storage, and 0.2% peracetic acid disinfection and dry storage. The horizontal dimension of the specimens and an average was established for analysis. Measurements were performed at four different storage times (hours): T0, T24, T48, T168. RESULTS: No statistical differences were found when T0 was compared to T168 for Pattern resin groups submitted to disinfection and storage in water (group 2b, p = 1.000) or peracetic acid solution (group 2c, p = 0.352). For Duralay groups, the use of peracetic acid solution did not affect the horizontal dimension of the specimens when T0 was compared to T168 only with water as a storage medium (group 1b, p = 1.000). Additionally, T0 did not differ from T24 for groups 1c (p = 0.553), 2b (p = 1.000), 2d (p = 0.234), and 2e (p = 1.000) and from T48 for groups 1d (p = 0.118) and 2b (p = 1.000). CONCLUSION: Within the studied conditions, the use of 0.2% peracetic acid can be safely used as a disinfectant solution regarding dimensional stability of AR-indexed IFPD until 7 days of storage. Horizontal discrepancies are dependent on acrylic resin type, time, and medium of storage.