Wax Record Research Articles

Evaluation of accuracy between extraoral Gothic arch tracing and various other methods assessing horizontal condylar guidance angle in completely edentulous patients: A systematic review and meta-analysis.

The aim of this systematic review and meta-analysis was to determine the accuracy of different methods of measuring horizontal condylar guidance (HCG) angle in comparison with extraoral Gothic arch tracing for completely edentulous patients. This was a systematic review and meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Two reviewers searched the EBSCOhost, Cochrane Library, and PubMed/MEDLINE databases and the Google Scholar search engine for in vivo studies, randomized controlled trials, cross-sectional studies, and quasi-experimental studies published from January 2005 to December 2022 on various other methods of determining HCG angle in completely edentulous patients compared with extraoral Gothic arch tracing method. Meta-analysis was conducted from the reported quantitative data. A total of 513 articles were obtained from different electronic databases, of which 22 studies were included for qualitative synthesis and 20 studies were included for meta-analysis. For the right side, a statistically significant difference was observed for panoramic radiograph (P < 0.05, pooled mean difference = 5.08 [2.17, 7]) and cephalogram (P < 0.05, pooled mean difference = 10.65 [8.81, 12.49]), whereas no statistically significant difference was observed for cone-beam computed tomography (CBCT) (P = 0.41, pooled mean difference = 4.39 [-6.10, 14.87]) and protrusive interocclusal wax record (P = 0.92, pooled mean difference = -0.45 [-9.62, 8.72]) as compared with extraoral Gothic arch tracing method. For the left side, a statistically significant difference was observed for panoramic radiograph (P < 0.05, pooled mean difference = 5.07 [1.95, 8.18]) and cephalogram (P < 0.05, pooled mean difference = 10.24 [8.65, 11.83]), whereas no statistically significant difference was observed for CBCT (P = 0.31, pooled mean difference = 4.05 [-3.74, 11.84]) and protrusive interocclusal wax record (P = 0.72, pooled mean difference = -1.21 [-7.86, 5.43]) as compared with extraoral Gothic arch tracing method. The cephalogram and panoramic radiograph obtained higher HCG angles in completely edentulous patients than extraoral Gothic arch tracing.

Abrupt Drying on the Southeast Coast of China During the Mid‐to‐Late Holocene Transition

AbstractIt is becoming increasingly clear that China experienced significant hydrological changes during the mid‐to‐late Holocene transition—a period characterized by societal changes. However, the nature of the hydroclimate anomaly as well as the direct consequences on societies in Southeast China remains unclear. Here, we present a leaf wax record from the Shuizhuyang peat deposit in Southeast China spanning the Holocene. The δD values of C29 n‐alkane (δDC29) showed a large positive shift up to 24‰ from 4.7 to 3.8 ka, which changed independent of vegetation proxies and could not be solely explained by precipitation δD variations. It is thus most likely to reflect abrupt drying, which is probably shaped by a more El Niño‐like mean state in the tropical Pacific Ocean. We hypothesize that such a significant change in hydroclimate might have promoted the development of mixed rice and millet farming on the southeast coast of China.

Leaf wax isotopes reveal distinct hominin paleoenvironments in the Eastern Qinling Mountains of central China

Here, we present the first leaf wax record in association with Paleolithic occupations in the Eastern Qinling Mountains of central China. This region has been the focus of numerous archaeological projects, as it contains evidence of some of the oldest (∼2.0–1.2 Ma) hominin occupations in eastern Eurasia and is one of the key areas yielding bifacial handaxe technology. Previous research demonstrates that these mountains represent a physio-geographic barrier that separates the semi-arid north from the sub-tropical south and defines northern and southern Paleolithic industries. Although evidence suggests models associated with the Qinling Mountains need refinement, our results demonstrate that there are observable differences between the southern and northern Qinling Mountains and are in good agreement with previous observations. Here, we use the carbon isotopic values (δ13C) of leaf wax lipids to reconstruct the ratio of C3 to C4 vegetation at long-term Pleistocene Homo erectus occupations of the Hanzhong and Luonan Basins of the Eastern Qinling Mountains. In Hanzhong, isotopic range is low (1.5‰) and vegetation was dominated by C3 vegetation (85–90%) throughout the middle to late Pleistocene. Paleolithic technologies associated with these stable vegetation regimes are dominated by expedient Mode I technologies throughout the entire record. Conversely, in Luonan, isotopic range is significantly higher (4.2‰) and C4 vegetation increases to approximately 40% during some periods, which represents the expansion of forest-grassland mosaics. These fluctuating vegetation regimes are also associated with the emergence of Mode II bifacial technology, suggesting variable environments triggered the need for multifunctional handaxe technology. Our research demonstrates that there are key differences between the southern and northern Qinling Mountains, and that the northern Qinling Mountains are associated with both forest-grassland mosaics and less expedient technologies. Finally, in both basins our records demonstrate that patterns in C3:C4 track Marine Isotope Stages and appear to operate on interglacial-glacial timescales.

Late Quaternary hydroclimate of the Levant: The leaf wax record from the Dead Sea

The eastern Mediterranean is projected to experience increases in drought and extreme rainfall in response to rising greenhouse gas emissions. Paleoclimate records from this region are crucial to further constrain the response of the water cycle to a globally warmer climate. Of these, the Dead Sea lacustrine record, collected by the Dead Sea Deep Drilling Project (DSDDP), provides a detailed history of climate change over the past 200,000 years and documents large-magnitude changes in regional water balance. Here, we analyze leaf wax isotopes (δDwax, δ13Cwax) on DSDDP 5017-1 and compare results to other proxies analyzed on the same core. The δDwax record closely resembles the speleothem δ18O record from nearby Soreq Cave, suggesting that both record a regionally coherent signature of glacial-interglacial cycles and the interplay between winter season rainfall and large-scale expansion and contraction of the Afro-Asian monsoon system. Principal components analysis of the pollen and core lithology shows that the first-order driver of variability in the Dead Sea paleoclimate record is global temperature, which controls effective moisture by modulating atmospheric evaporative demand. Leaf wax, pollen, and core lithology all suggest radical changes in the annual cycle of precipitation during the peak of the Last Interglacial. We hypothesize that the Dead Sea Basin experienced a dual-rainfall regime during this time, with intensified winter storms and a summer monsoon season. While these changes were driven by the Earth's precessional cycle, model simulations suggest a similar expansion of the African monsoon domain into the Arabian Peninsula under elevated CO2 levels. The Last Interglacial climate of the DSB provides a glimpse of what future climate in the southeastern Mediterranean region could look like.

Accuracy of recording edentulous jaw relations by using an optical jaw tracking system: An in vitro study.

To establish a recording method for edentulous jaw relations and to perform quantitative accuracy evaluation in vitro. Maxillary and mandibular edentulous arch models and complete dentures were mounted on an articulator, simulating protrusion (A), left and right laterotrusion (B and C), and small opening jaw relations (D), aided by metal foil wax record. Using the tracking system, 3D trajectories of targets were recorded from intercuspation to A, B, C, and D, then used to rehabilitate digital arch relations of A, B, C, and D in the test group. Axial model surfaces were pasted with six pairs of positioning cylinders. The center points of the bottom surfaces of the cylinders in A, B, C, and D were measured to rehabilitate digital arch relations in the control group. With the maxilla as the common area, arch relations of the test group were registered in the control group; 3D deviations of the mandible were calculated, and displacements in horizontal left/right, horizontal anterior/posterior, and vertical directions were analyzed. 3D deviations of the mandible in A, B, C, and D were 131 ± 39 μm, 133 ± 44 μm, 120 ± 51 μm, and 112 ± 52 μm, respectively. Mean absolute values of displacements of the mandible were less than 200 μm. By using the optical jaw tracking system, the accuracy of jaw relation records as measured on an articulator was acceptable for clinical demand. Further investigations among patients are required to clinically verify the results of this study.

Plant wax integration and transport from the Mississippi River Basin to the Gulf of Mexico inferred from GIS-enabled isoscapes and mixing models

Understanding the fate of terrestrial plant waxes from source to sink is critical for improving paleoclimate interpretations from sedimentary plant waxes. However, there is limited knowledge about the controls on plant wax integration and transport in large catchments with multiple biomes and climates. To address this lack of understanding, we investigated the vegetation and climatic controls on plant wax integration and transport from the Mississippi River Basin (MRB), the largest river in the U.S., to the Gulf of Mexico (GOM). We first estimated the geographic distribution of n-alkane carbon (δ13Calk) and hydrogen (δ2Halk) isotopic compositions (i.e. isoscapes) in the MRB using plant isotope fractionation calibrations from North America and similar climate regions for the pre-industrial. We utilized two different vegetation maps (i.e. biome map and %C4 map) and two plant isotope fractionation estimation approaches, and discussed advantages and disadvantages of each method. Then, we developed mixing models weighting the isotope values by biological and climatic parameters (i.e. vegetation area, n-alkane concentration by chain lengths, net primary productivity (NPP), and runoff) and their combinations to test the sensitivity of basin-integrated plant wax isotopic compositions to these variables. Our approach does not factor in soil stocks of plant wax nor degradation in transit, as future work will need to constrain these factors for the MRB for the period of interest. Vegetation area weighting alone predicted relatively high C4 plant contributions to the pool of waxes exported from the basin. When n-alkane concentration in leaves, NPP, or runoff was considered, the contribution of forest-derived plant waxes increased. Sensitivity of plant wax isotopic compositions to productivity and transport efficiency varied among models and chain lengths. For example, n-C29 alkanes were sensitive to plant wax contribution increases from forests whereas n-C33 alkanes were more sensitive to increases in C4 grassland productivity. The plant wax concentration and NPP were combined as an estimate for total wax productivity, and a combination of this total wax productivity and runoff were used to simulate both production and transport. These multi-parameter models estimated the highest plant wax contribution from C3 forests because these areas were calculated to have the highest productivity and greatest runoff. Despite large differences in δ13Calk and δ2Halk values across the MRB, variation in the predicted δ13C and δ2H of exported n-alkanes is small across all models. This small range is consistent with a calculated predominance of plant wax export from wet and tree-dominated biomes and suggests that drier and C4 grass-dominated biomes may be under-represented in the sedimentary plant wax record.

A δ13C and δ2H leaf wax record from the Late Quaternary loess-paleosoil sequence El Paraíso, Central Spain

The Mediterranean Peninsula increasingly suffers from droughts and aridity, the first consequences of global climate change in that region. Precise scenarios for the region's future climate predictions require knowledge about the processes of past climate changes, but information about the Western Mediterranean climate and its history is controversial. For this study, we applied compound-specific δ13C and δ2H analyses on long-chain n-alkanes in the ~8 m El Paraíso loess-paleosoil sequence (LPS), Central Spain, to investigate climate and environmental changes during the Late Quaternary. The δ13C values are most enriched during marine isotope stage (MIS) 3, indicating more arid conditions, while lower values during MIS 4 and 2 are interpreted to document more humid conditions. Low values are also recorded for the Holocene colluvium, which can at least partly be explained with higher concentrations in atmospheric CO2. The δ2H values are mostly enriched during the last glacial compared to the Holocene. We suggest that this is mainly controlled by isotopic effects related to the moisture source, yet other possible effects like evapotranspirative enrichment and changes in atmospheric circulation patterns shouldn't be ruled out. Our results corroborate previous findings based on leaf wax patterns, geomorphological records, and climate models. They all indicate relatively humid conditions during MIS 2 compared to more arid phases during MIS 3.

Modified protrusive wax record in measuring condylar path angle in relation to ethnic variations

Modified protrusive wax record in measuring condylar path angle in relation to ethnic variations

Compound-specific carbon isotope records of vegetation and hydrologic change in central Sulawesi, Indonesia, since 53,000 yr BP

Lake Matano (2°29.1′S 121°20′E) in central Sulawesi, the deepest and one of the largest lakes in Indonesia, provides an excellent opportunity to reconstruct long-term hydrological and vegetation changes at the heart of the Maritime Continent within the tropical Western Pacific Warm Pool. We measured the carbon isotopic composition of terrestrial leaf waxes (δ 13 C wax ) in new sediment cores from Lake Matano to understand regional variations in vegetation and their interactions with local and high latitude climate forcings during the past 53 kyr. Variations in δ 13 C wax record the expansion and contraction of C 3 versus C 4 vegetation as well as changes in plants' carbon and water use efficiency and, by inference, regional hydroclimate. During Marine Isotope Stages 1 and 3, more negative δ 13 C wax values indicate that closed-canopy C 3 rainforests predominated in Sulawesi, reflecting a wetter, less seasonal climate. In contrast, more positive δ 13 C wax values record a terrestrial ecosystem with more abundant open canopy vegetation and possible expansion of C 4 grasses between 29 and 14 ka BP, indicating that during Marine Isotope Stage 2, including the Last Glacial Maximum, the climate was more arid, likely with increased precipitation seasonality, in central Sulawesi. Comparison of our record with other paleovegetation and paleohydrological records from Sulawesi and nearby islands suggests coherent long-term hydrological changes in central Indonesia that appear to be sensitive to high latitude climate across glacial-interglacial boundaries. However, variations in the amplitude of the response of vegetation to these glacial-interglacial forcings highlight the importance of regional topographic control on climate and vegetation and suggest an important role for higher elevations in maintaining rainforest refugia during regionally arid time intervals when C 4 savannas and grasslands expanded at lower elevations. • Vegetation and hydrologic changes in central Sulawesi are sensitive to high latitude climate forcings across glacial-interglacial boundaries since 53 kyr BP. • Altitudinal gradients within the interior of Indonesian islands influence local manifestations of hydrological and vegetation changes at orbital timescales. • Higher elevations providing rainforest refugia during arid and more seasonal interval.

Comparative study to evaluate the accuracy of polyether occlusal bite registration material and occlusal registration wax as a guide for occlusal reduction during tooth preparation

The use of different materials and techniques has been studied to decide the safest quantum of reduction of the occlusal surfaces. However, these methods provide limited information as to the actual amount of reduction with limitations in accuracy, accessibility and complexity. The objective of this study was to compare and evaluate the reliability of the most commonly used occlusal registration wax that with polyether bite registration material as a guide for occlusal reduction required during tooth preparations. For the purpose of this study, 25 abutment teeth requiring tooth preparation for fixed prosthesis were selected and tooth preparations carried out. Modeling wax strips of specific dimensions were placed onto the cast of prepared tooth, which was mounted on maximum intercuspation on the articulator and the articulator was closed. The thickness of the wax registration was measured at three zones namely two functional cusps and central fossa. Similar measurements were made using the polyether bite registration material and prosthesis at the same zones. The data was tabulated and was subjected to statistical analysis using anova test and Tukey honestly significant difference test. The differences in thickness between wax record and prosthesis by 0.1346 mm, whereas the difference between polyether and prosthesis was 0.02 mm with a P value of 0.042, which is statistically significant. This means that the wax record was 8.25% larger than the prosthesis while polyether was just 1.27% larger than the prosthesis. The clinical significance of the above analysis is that Ramitec polyether bite registration material is most suitable material when compared with commonly used modeling wax during the tooth preparation.

A Comparative Evaluation of Static and Functional Methods for Recording Centric Relation and Condylar Guidance: A Clinical Study

To evaluate and compare the centric relation and horizontal condylar guidance using interocclusal wax and extra oral Gothic arch methods and subjective evaluation of dentures thus fabricated. Centric relation and horizontal condylar guidance was recorded by using interocclusal wax and gothic arch tracing in 28 completely edentulous patients. These records were transferred to the articulator and difference in both values was recorded. After that patients were divided in two groups according to the centric relation and horizontal condylar guidance recording method used to achieve balanced occlusion. Response of the dentures was subjectively evaluated using "Woelfel subjective evaluation criteria". Centric relation recorded by both the methods did coincide in 7.14% of patients. Centric relation recorded by interocclusal wax was posterior to Gothic centric relation in 21.43% of patients, and anterior to Gothic centric relation in 71.42% patients. Gothic arch tracings gave higher mean guidance values on both the sides as compared to protrusive wax record in all the subjects, although the difference was statistically insignificant (P>0.05). Subjective evaluation showed statistical insignificance for all the parameters in both groups. Gothic arch method records the centric relation at a more posterior position than the Static method, but it does not make any difference in clinical performance of the complete denture. Horizontal condylar guidance angle was approximately similar by both the methods.

Dimensional accuracy of upper complete denture bases: the effect of metallic flask closure methods

To verify the dimensional accuracy of upper complete denture bases under the effect of different methods of metallic flask closure. Wax record bases were assigned to six groups: 1-2: traditional clamp; 3-4: RS system; and 5-6: flask with screws. Flasks were immediately polymerised or bench stored for 6 h prior to polymerisation. Resin base-cast sets were sectioned at regions corresponding to the canines, first molars and posterior palatal zone. Gap discrepancies were measured at five points: right and left ridge crests, palatal midline, and right and left marginal limits of the flanges. An optical micrometer was used for measurement purposes. Data were submitted to anova, and the means compared by Tukey's test (alpha = 0.05). Results revealed significant differences in the flask closure technique, polymerisation time, section, and their interactions. Discrepancy values for the RS system and flask with screws were significantly lower than those related to the traditional clamp, regardless of whether resin polymerisation was immediate or delayed for 6 h. Flask closure methods should be considered when the denture base stability and comfort of the patient are being assessed during clinical use of the dentures.

Association of the canine guidance angle with maxillary and mandibular intercanine widths and anterior alignment relapse: Extraction vs nonextraction treatment

Long-term stability is an important measure of the success of orthodontic treatment. Research in the 1970s suggested that premolar extraction treatment had poor stability over the long term. The purpose of this prospective follow-up study was to investigate changes in intercanine widths and the irregularity index during the postretention phase in patients treated with and without extractions. Associations between the maxillary canine guidance angle and the mandibular intercanine widths and the mandibular irregularity index were also examined. Two groups of 30 patients each, with and without premolar extractions, were studied and the results compared. Records were taken at pretreatment, at bracket removal, at the end of retention, and out of retention. The times out of retention were 6.3 years for the nonextraction group and 6.5 years for the extraction group. Stone casts were mounted on an articulator with an anatomical facebow and a central wax record. The measurements were made with a 3-dimensional digitizer. Maxillary and mandibular intercanine distances behaved differently. The mandibular intercanine distance showed a net decrease between pretreatment and follow-up, whereas the maxillary arch had a net increase. The maxillary canine guidance angle at the end of retention, measured to the axis-orbital plane, was highly associated with relapse of mandibular anterior alignment and change of the mandibular intercanine distance. Methods are needed that consider the anatomical configuration of the teeth for bracket selection before treatment. Individualized brackets (torque) should then be coordinated with the guidance angle of the maxillary teeth.

Dust influx reconstruction during the last 26,000 years inferred from a sedimentary leaf wax record from the Japan Sea

We obtained the high-resolution record of terrestrial biomarkers (C 29 and C 31 n-alkanes) for the last 26,000 years from Oki Ridge in the south Japan Sea that enabled us to discuss millennial scale climate changes. Our sampling resolution for the biomarker during the major deglaciation period (10–19.5 cal ka BP) is 300 years and for the elemental analyses (total organic carbon and total nitrogen) is as good as ca 200 years. The estimated mass accumulation rate of these molecules during the last glacial period is substantially higher than during the Holocene. They also exhibited two distinct peaks at 17.6 cal ka BP and 11.4 cal ka BP, which are coincident with Heinrich Event 1 and the latest stage of the Younger Dryas, respectively. The unique oceanographic setting of the Japan Sea tends to preferentially preserve organic material of aeolian origin. The nature of our biomarker record in fact suggests a strong aeolian signal, and hence their flux to the Japan Sea potentially reflects the climate conditions of the dust source regions and transport intensity. Our results are consistent with previously reported monsoon variations based on other proxies that is indicative of a strong linkage between North Atlantic climate and Asian monsoon intensity.

Three-dimensional dental arch and palatal form changes after extraction and nonextraction treatment. Part 3. Transversal and sagittal palatal form

The purpose of this study was to investigate changes in the palatal form in patients treated with and without premolar extractions. Records collected at pretreatment, at bracket removal, at the end of retention, and 5 years out of retention were examined. Stone casts were mounted on an articulator with an anatomic face-bow and a central wax record, and measurements were made with a 3-dimensional digitizer. The hypothesis that orthodontic treatment with premolar extractions changes the palatal form was verified.

Three-dimensional dental arch and palatal form changes after extraction and nonextraction treatment. Part 1. Arch length and area

The purpose of this study was to investigate changes in arch length, arch area, and irregularity index in patients treated with and without premolar extractions. Records collected at pretreatment, at bracket removal, at the end of retention, and 5 years out of retention were examined. Stone casts were mounted on an articulator with an anatomic face-bow and a central wax record, and measurements were made with a 3-dimensional digitizer. In general, the maxillary arch exhibited less relapse tendency than did the mandibular arch for both patient groups. In general, the extraction group showed the same relapse tendency as the nonextraction group.

Three-dimensional dental arch and palatal form changes after extraction and nonextraction treatment. Part 2. Palatal volume and height

The purpose of this study was to investigate the changes in palatal volume and palatal height in patients treated with and without premolar extractions. Records were collected at pretreatment, at bracket removal, at the end of retention, and 5 years out of retention. Stone casts were mounted in a SAM 2 articulator with an anatomic face-bow and a central wax record, and measurements were made with a 3-dimensional digitizer. The hypothesis, that orthodontic treatment with premolar extractions changes the palatal form, was verified. Increases in palatal volume and height were demonstrated in the nonextraction group. The extraction group showed a decrease in palatal volume but could compensate for some loss by an increase in volume in the anterior segment.

Comparison of condylar guidance setting obtained from a wax record versus an extraoral tracing: A pilot study

Statement of the problem. Protrusive condylar angles can be determined by use of wax protrusive records (WPR), pantographic tracings (PT), and occlusal wear facets. These methods generate different angles in the same patient. Purpose. The purpose of this study was to compare the condylar inclination angles found by use of the WPR in a Hanau articulator with those found by use of the Whip-Mix PT quick-set recorder. The occlusal wear facet method was not part of this study. Material and Methods. Ten subjects were chosen at random from a dental school patient population. All subjects had a majority of maxillary and mandibular teeth present and according to the examination criteria used in the school's Division of Occlusion, they were healthy with no signs/symptoms of temporomandibular disorders. The WPR was accepted when it was evident that the patient had protruded straight forward at least 6 mm anterior to centric relation, as shown on the Hanau articulator by the condylar spheres having moved anteriorly an equal distance of 6 mm on both sides. The condylar inclination on the articulator was adjusted accordingly. The PT was used according to the manufacturer's directions, which included the use of an intraoral clutch adapted to the mandibular arch, connected to an extraoral facebow with bilateral inscribing pointers. A holder frame was adapted to the face with bilateral flags where the inscribing pointers traced the protrusive movement of the jaw. All the readings were in degrees. No control was used in this project. To test whether there was a significant difference between the 2 independent samples, a Mann-Whitney U test was performed (P=.01). Results. The mean results for the WPR were as follow: right side (28.1 degrees, SD 8.94); left side (31.50 degrees, SD 9.73). For the PT, results were: right side (41.10 degrees, SD 7.53); left side (35.5 degrees, SD 6.43). When right and left side protrusive condylar angles were combined, the values were: WPR (29.80 degrees, SD 9.25); PT (38.30 degrees, SD 6.98). The differences on the right condylar values were significant (P=.01). There was no statistical difference on the left side. Conclusions. Within the limitations of this study, it was concluded that the PT technique yielded greater values for the protrusive condylar inclination than the WPR. (J Prosthet Dent 2003;89:54-9.)

Absence of association between a preferred chewing side and its area of functional occlusal contact in the human dentition

Preference for a particular chewing side may be influenced by several factors, one of which could be the functional contact area on each side of the dentition. In this study, interocclusal wax records were made for each of the 30 subjects. A digital image of the transilluminated wax record was analysed to group ‘grey’ values into categories of wax thickness. The total area for tight and intermediate tooth contacts was calculated for both the left- and right-hand sides of each subject. The chewing-side preference was recorded. No correlation was found between the area of occlusal contact on one side and the preference for chewing on that side. Occlusal contact area does not appear to be a determinant of chewing-side preference.

Accuracy of laminated wax interocclusal wafers

Different types of wax interocclusal records were tested to determine if the type of recording material affects cast position when dental plaster is used to mount casts. The results indicate that a difference in the type of wax record is not a significant factor in cast fixation.