Occlusion Rims Research Articles

Comparison of conventional and digital impression approaches for edentulous maxilla: clinical study

BackgroundThe expectations for the clinical and laboratory phases of tissue-supported complete dentures (TSCDs) are changing. Currently, there is a trend towards fast, comfortable, reliable, and low-cost methods. In TSCD impressions, simplified impression and digital impression methods involving the use of an intraoral scanner (IOS) are becoming preferable. Given this situation, this study aims to compare different conventional and digital impression methods used in TSCDs.MethodsPatients with maxillary complete edentulism and healthy oral mucosa were included in this study. In the digital group, two different impressions were made using an IOS (Trios4) without (D1) and with (D2) artificial intelligence scanning (AI-Scan). In addition, a modified impression (D3) was made using the IOS in two steps, including the occlusal rim. In the conventional group, a two-step impression (C1) using an individual tray with zinc oxide eugenol and a one-step simplified impression (C2) using a stock tray with irreversible hydrocolloid were made. The comparison groups were determined to be C1-C2, C1-D1, D1-D2, and D1-D3. The best-fit algorithm was used to superimpose the impressions to be compared. The right and left vestibular areas, postdam area, palatal area, right and left matching area, entire surface, and borders were evaluated separately.ResultsFifteen patients were included in this study. In the C1-C2 group, the mean deviation at the borders was statistically significant (p = 0.01). No regions in the C1-D1 and D1-D3 groups exhibited significant differences in the mean amount of deviation (p > 0,05). In the D1-D2 group, the mean deviation in the palatal area was significant (p = 0,03).ConclusionIn maxillary edentulism, digital impressions have shown comparable results to conventional impressions, suggesting promising implications for clinical applications.Trial RegistrationThe clinical trial has been registered (ClinicalTrials.gov ID NCT06400277, registration date 06/05/2024, ‘retrospectively registered’).

The Effect of Average Value Mounting and Facebow Transfer on Condylar Guidance Settings in a Semi-Adjustable Articulator - A Comparative Study using Digital Lateral Cephalographs in Edentulous Patients.

While we attempt to restore occlusion in completely edentulous patients there is a consensus among clinicians to articulate the cast using average value and avoid performing facebow transfer. Various studies question the application of facebow transfer in the fabrication of removable complete denture fabrication. This study was therefore aimed to study the effect on condylar guidance with casts mounted by the facebow method, Bonwill's method, and radiographic method. A cross-sectional study was performed using casts of edentulous patients attending the Department of Prosthodontics. After establishing a tentative jaw relationship using wax occlusal rims in the edentulous participants, the casts were mounted by Bonwill's method and the facebow transfer method to a semi-adjustable articulator. Protrusive records of the subjects were used to program the articulator to obtain the condylar guidance values. Digital lateral cephalographs were made both in centric and protrusive jaw relationships. The mandibular condyles were then traced and overlapped to obtain radiographic values. The condylar guidance values obtained by Bonwill's method, facebow method and radiographic method were compared using Wilcoxon's signed rank test and Mann-Whitney U test. The SPSS Statistics for Windows (Version 21.0. Armonk, NY, USA:IBM Corp.), and, at a probability value of 0.05, the significance of every statistical test was predetermined. Ten edentulous 45-70 year olds participated in the study. The mean discrepancy between radiography and facebow methods was 12.8° for the right side and 12.7° for the left (P < 0.005). The difference between radiography and Bonwill's methods was significant (P < 0.005), with a mean difference of 34.3° for the right side and 34.7° for the left side. The difference between Bonwill's method and the facebow method was significant (P < 0.005), with a mean difference of 21.5° for the right side and 22° for the left side. The condylar guidance values obtained by clinical methods (Bonwill's and Facebow) were significantly lesser (P < 0.005) compared to the values obtained by radiographic method.

A method of fabricating a stackable CAD-CAM custom record tray for complete dentures

Digital complete denture fabrication has advanced with the integration of computer-aided design and computer-aided manufacturing (CAD-CAM), intraoral scanning, and 3-dimensional printing. A method of fabricating a stackable CAD-CAM custom record tray for complete dentures is introduced. The method combines a custom tray, record base, and occlusion rim in a single piece.

Evaluation of the Suitability of The Established Standard Height of Occlusal Rim Blocks Among the Dental Clinicians in Makerere University Dental Hospital In Uganda

Evaluation of the Suitability of The Established Standard Height of Occlusal Rim Blocks Among the Dental Clinicians in Makerere University Dental Hospital In Uganda

An alternative technique for transferring ala-tragus plane to occlusion rim using a novel device

Establishing an optimal occlusal plane and adjusting the prosthesis in accordance to it are a prerequisite before initiating any prosthodontic rehabilitation procedure. A salient step in this procedure is to transfer the established plane on the record blocks or mounted diagnostic casts with accuracy. Although conventional equipment such as the fox plane analyzer and its variants are commonly used for aligning the occlusal plane in accordance to the ala-tragus plane, it is time-consuming and tedious to transfer the same onto the occlusion rims for dental students and young practitioners. The proposed design usage would be more time-saving as the rim need not be taken out from the patient’s mouth for minute corrections of the occlusal plane each time a cant is suspected using conventional fox plane analyzing device, making it a single-step transfer. Therefore, this article proposes an equipment design for a quick transfer of the ala-tragus plane to the wax occlusion rims. Clinical implication: The proposed equipment design may prove beneficial for clinicians as well as dental students to transfer the ala-tragus plane on wax occlusion rims in a single step during jaw relation, hence reducing the chair side time and contributing to the accuracy of procedure.

Statistical Investigation of the Standard Height of Occlusal Rim Blocks among Patients Attending Makerere University Dental Hospital, Kampala, Uganda

Edentulous patients desire to reinstate oral function and aesthetics in the most comfortable state and to regain their self-esteem. Due to racial anatomic differences, there is a need to ascertain the standard height of Occlusal Rim Blocks (ORBs) for edentulous patients in Uganda. This study was aimed at statistical investigation of the standard height of ORBs among patients attending Makerere University Dental Hospital, Kampala, Uganda. This was a cross-sectional quantitative study that comprised 240 pairs of wax ORBs requested by clinicians for patients in need of complete dentures. Consecutive sampling was used to select the ORBs. The height of the anterior and posterior portions of the maxillary and mandibular ORBs were recorded using a pair of pliers and a flexible ruler, and data were entered into Excel and exported into STATA software version 15 for analysis. The mean height for the anterior portion of maxillary ORBs was 19.4 mm and for the posterior, 17.4 mm after adjustment while the mean height for the mandibular counterparts was 16.4 mm and 16.0 mm, respectively. There was a statistically significant difference between the mean height of ORB before and after adjustments and between the newly established and internationally accepted standard height of ORB. There was no significant sex difference in the mean height of ORBs. Overall, the mean height of ORBs for the Ugandan population was significantly shorter than the internationally accepted standard height. Keywords: Bite registration, Complete denture, Dental hospital, Edentulous patients, Height, Occlusal rim blocks

Fuctional balancing in complete dentures- A case report revisiting the paterson’s technique

: A good occlusion is the key to the comfort and longevity of a prosthesis. : This case report presents a 63 year old male patient who reported with the complaint of difficulty in chewing since past 3 months.: On examination, the patient presented with completely edentulous upper and lower arch. A detailed case history was recorded followed by, primary and secondary impressions. The maxillo-mandibular relation was recorded conventionally on wax occlusal rims. A trough was then made in the wax and filled with a mixture of dental plaster and carborundum. The mix was kept 2mm above the plane. The rims were inserted and the patient was instructed to perform lateral and protrusive movements resulting in the incorporation of the compensating curves. The recorded plaster index served as a guide for the teeth arrangement. The denture was processed and delivered with very minimal need for post insertion corrections.: According to Paterson (1923), an articulator with lateral movements is not necessary to establish a balanced occlusion when using the functional technique. The teeth arrangement is entirely dependent on the established curves for obtaining balance.: Various techniques are cited throughout the literature to provide a successful prosthesis. With all the advances in the digital era, denture fabrication is not an automated procedure. It is pertinent that the clinicians master the fundamentals of prosthesis fabrication, without which any amount of technology and/or persistence might be in vain.

Digitally printed custom trays assembled with occlusion rims and gothic arch tracing devices attached with tenon-and-mortise joints for biofunctional complete dentures: A dental technique

A novel technique of digitally printed custom trays assembled with occlusion rims and gothic arch tracing devices attached with tenon-and-mortise joints for biofunctional complete dentures that could be delivered in 2 visits is presented. This technique takes advantage of closed-mouth impressions and objective jaw relation records by following the biofunctional prosthetic system concept with high efficiency and reduced labor.

PROSTHETIC TREATMENT OF PATIENT WITH MANDIBLE RESECTION

Background: Literature findings indicate an increase in mandible resection cases. Retention and stability of dentures are the main issues in the prosthetic treatment of these defects. Aim: The aim of the presented clinical case is to explore the possibility of prosthetic treatment of a patient with mandible resection of the frontal area. Materials and methods: The clinical case monitors the prosthetic treatment of a 38-year-old patient with mandible cancer and resection in the frontal zone. The treatment plan was based on taking preliminary alginate impressions and developing gypsum models. It is planned to develop a partial acrylic denture sealed with silicone material. Additional preparation of the gypsum master model in the resection area took place in order to achieve the equal thickness of the special silicone material. The base of the alveolar bone was restored with hard plaster. In addition, the occlusal rim was fabricated with the purpose of establishing the centric relation and occlusal relationship. The denture was fabricated by acrylic resin with a low quantity of residual monomer and adjusted after adding silicone material over the resected part with functional tests to complete the design of the defect area. Results: The accessed treatment results indicate good retention and stability of the denture. The application of silicone material provided a non-traumatic transition of the masticatory pressure without decubital ulcers in the resected zone. Conclusion: The application of appropriate prosthetic treatment methods in patients with mandible resection leads to the successful restoration of feeding and speaking functions.

Role of Mucobuccal Sulci in Determination of Occlusal Vertical Dimension in Dentate Subjects.

Aim: To find out the distance between the mucobuccal sulci of maxillary and mandibular arches and the cusp tips of posterior teeth and evaluate the occlusal vertical dimension in dentate subjects. Study Design:Cross sectional observational study. Place and duration: Prosthodontic department of Lahore Medical and Dental College, Lahore, from 2nd September 2022 till 2nd December 2022. Methodology: A total of 45 dentate subjects including 20 males and 25 females were selected. Alginate impressions (irreversible hydrocolloid) of both arches were taken in stock trays. Impressions were poured in hard plaster and stone casts were fabricated. Digital vernier caliper with accuracy of 0.01mm was used for recording the distance from the depth of mucobuccal sulci of both arches to the cusp tips of all posterior teeth of the respective arches. The distance from maxillary mucobuccal sulcus to the mandibular mucobuccal sulcus in maximum intercuspation was also calculated. Result: The distances measured from the maxillary mucobuccal sulcus to the buccal cusp tips of maxillary first premolar, second premolar and first molar were found to be 16.86mm; 15.94mm, and 15.45mmrespectively. The distances measured from the mandibular mucobuccal sulcus to the buccal cusp tips of mandibular first premolar, second premolar and first molar were 17.02mm, 15.14mm and 14.26mmrespectively. The mean distance recorded from the depth of maxillary and mandibular sulci in maximum intercuspation positions showed shortest distance at first molar areai.e.; 26.88mmas compared to the distance found in first premolar 35.22mm and second premolar 35.63mmareas. Conclusion: The mean distances recordedbetween maxillary and mandibular sulci in intercuspation position were 35.22mm, 35.63mm and 26.88mm respectively. These values may be helpful in determination of occlusal vertical dimension by selecting appropriate teeth and shaping occlusal rims while fabricating complete dentures Keywords: Dentate, Dental arch, Mucobuccal sulcus, Maxilla, Mandible, Occlusal vertical dimension, Posterior teeth.

Comparing the accuracy of occlusal vertical dimension transfer in CAD-CAM dentures.

There are different methods to transfer occlusal vertical dimension (OVD) when fabricating complete dentures, but it is not clear which method yields the most accurate transfer. This study investigated the accuracy of transferring the OVD of the maxillary/mandibular relationship when designing and fabricating digital dentures by evaluating two commonly used workflows: duplicate dentures (DDs) and occlusion rims (ORs). Mounted edentulous casts were used to simulate a completely edentulous patient. These casts were used in two workflows: (1) DD workflow where complete dentures were fabricated and relined (n=15), and (2) OR where final impressions and ORs were constructed (n=15). Relined dentures and ORs with fiduciary markers were then scanned and virtually articulated, then exported as STL files. A scan of the articulated casts (simulated patients) with fiduciary markers embedded was also exported as an STL file and used as a control. STL files for each workflow were superimposed over the control and analyzed in 3D inspection software (Geomagic Control X, 3D Systems, NC) for deviations (mm) at three different locations. Average 3D deviations were compared among the groups using a two-way ANOVA (α-0.05). The average deviation for OR was significantly larger than DD at all locations of measurement [F=46.00, p<0.0001]. The majority of the measurements (98.9%) had a positive deviation value, indicating increased OVD. The overall deviation for the OR group from the control was 0.72±0.13mm versus 0.45±0.23mm for the DD group. There was no difference in deviation between the points of measurement and no interaction between the location and method [F=0.02, p<0.98]. The DD workflow exhibited less deviation in the transfer of OVD than the OR workflow. However, the deviation was small and may not be clinically significant.

A simplified technique for fabricating complete dentures for patients with Parkinson’s disease: a case report

Background and Objective: Parkinson’s disease is a neurological disorder that affects 1% of individuals aged 60 years and older. The associated symptoms can impose limitations on the available dental treatment options. Case description: This case report follows the CARE guidelines and presents an adapted and simplified technique to fabricate complete dentures for a 74-year-old male edentulous patient with Parkinson’s disease. This modified technique enabled the fabrication of complete dentures in 4 clinical sessions of approximately 40 minutes. The first session involved manufacturing a preliminary impression with fast-setting alginate. The base plates and occlusal rims were then adjusted for artificial teeth arrangement during the second session. The final prosthesis was completed in the third session, which involved a teeth try-in and fabrication of a functional impression with low-melting thermoplastic material and polyether. Finally, denture installation was performed in the fourth session and follow-up consisted of 3 weekly sessions. Discussion: Considering that the treatment provided satisfactory aesthetics and function, mastication and socialization benefits, and improved the self-esteem and well-being of the older patient with Parkinson’s disease, the authors suggest this adapted and simplified technique for fabricating complete dentures. Keywords: Parkinson’s disease; complete denture; aged.

Hybrid tracer - A modified novel extra oral tracer.

Gothic arch Tracing has been a common modality in the recording of centric jaw relation. There has been two ways of recording the gothic tracing. They are extra oral and intra oral tracing. Among the extra oral tracers hight tracers are the most used tracers. Intra-oral and extra-oral tracers have a number of individual advantages and limitations. With the idea to overcome the short comings of both the tracers, hybrid tracers were made. Hybrid tracers could be a good alternative to the Hight-tracer in recording centric relation and can provide better clinical and teaching experience to the students. The hybrid tracer is a two-component assembly, upper and lower component. The upper component has a central bearing plate and stylus in continuation with the central bearing plate. The lower component has central bearing device with three central bearing points one anteriorly and two posteriorly, and it has a tracing platform (15×35mm) in continuation with the central bearing device. The length of these upper and lower components ismade to confine within the incisal rod of semi adjustable articulator. hybrid tracers showed more accuracy while recording the centric jaw relation. There was more stability and equalization of pressure during the movement due to a tripod effect of three screws. Hence it provided more precise recording and being less technique sensitive. It was also more comfortable and acceptable by the patient. hybrid tracers hence will provide more accuracy and precision in recording of horizontal jaw relation. This will in turn help in fabricating a successful prosthesis and enhance the well-being of the patient. This tracer will also be significant in institutions for educational purpose. Hybrid tracers are simple, non-technique sensitive, provide balance, equalization of pressure, stabilize the occlusal rims well, are close to the centre of rotation providing precise record and provide easy access and visibility to the operator which will help the operator in guiding the patient well for a correct jaw relation.

A technical and clinical digital approach to the altered cast technique with an intraoral scanner and polyvinyl siloxane impression material

This technique digitalizes the clinical and laboratory steps of fabricating removable partial dentures (RPDs) with the altered cast technique. An intraoral scanner was used to capture the mandibular Kennedy class II partially edentulous arch. An RPD framework was fabricated digitally and then combined with a custom tray with a wax occlusal rim. A conventional polyvinyl siloxane altered cast impression was made and then digitalized both intraorally and extraorally, followed by a digital interocclusal record. The resulting scan was modified to produce an additively manufactured cast. The teeth and gingival components were then designed and fabricated with a combination of additive and subtractive manufacturing, followed by the conventional acrylic resin pour technique. The definitive prosthesis was completed with minimal conventional techniques and without the use of gypsum, prefabricated teeth, or a physical articulator. The technique reduces the number of appointments and achieves the functional extension of the prosthesis through border molding, which is not possible with intraoral scanning.

Analysis of the distance between lingual frenal attachment and mandibular incisal edge position in establishing occlusal plane in three different races.

The orientation of the occlusal plane forms the basis for the arrangement of teeth conducive to satisfactory esthetics and function, making it one of the most important clinical procedures in prosthodontic rehabilitation. This study aimed to analyze and compare the vertical distance between the anterior attachment of lingual frenum (AALF) and the incisal edge of mandibular central incisors among three races in Malaysia. The sample consisted of 63 dentate subjects (21 Malays, 21 Chinese, and 21 Indians) who were chosen based on the inclusion criteria. Two models were made using irreversible hydrocolloid impressions, and an average of the value was obtained. Lingual frenum was recorded in function. Casts were fabricated with dental stone. AALF was marked and the vertical distance was measured using a caliper. In Malays, the mean and standard deviation of the vertical distance were 14.2 ± 0.9 mm, with a range of 12.3-16.0 mm; in Chinese were 14.4 ± 0.9 mm, with a range of 12.0-16.9 mm; and in Indians were 15.1 ± 1.0 mm, with a range of 13.0-17.2 mm. The difference among the three races regarding the distance between AALF and the incisal edge of mandibular central incisors was statistically significant (P < 0.05). Among the three races, Malays and Indians have the greatest mean difference. According to the results of the current study, the distance between AALF and the incisal edge of mandibular central incisors might be a proper criterion for the initial adjustment of occlusal rims. The values obtained from three different races were significantly different from one another, hence a different range of values was used to establish occlusal height for different races.

Dimensional changes of complete dentures fabricated by milled and printed techniques: An in vitro study

Statement of problemInformation on the dimensional changes in maxillary and mandibular dentures made by using computer-aided design and computer-aided manufacturing (CAD-CAM) techniques under uniform testing conditions is lacking. PurposeThe purpose of this in vitro study was to evaluate the dimensional changes and reproducibility of maxillary and mandibular dentures by using CAD-CAM-milled and 3D-printed techniques. Material and methodsMaxillary and mandibular edentulous models with wax occlusal rims were scanned, and dentures were designed by using a CAD software program and fabricated by using 2 techniques and materials: CAD-CAM-milled (CCM) and 3D-printed (3DP). The 3DP fabrications included 4 subgroups: dentures printed with a 90-degree build angle with UV light polymerization on the reference model (3DP 90M), dentures printed with a 90-degree build angle and light polymerization without the reference model (3DP 90), dentures printed with a 45-degree build angle with light polymerization on the reference model (3DP 45M), and dentures printed with a 45-degree build angle and light polymerization without the reference model (3DP 45). The preprocessing and postprocessing scan files of each denture produced by CCM and 3DP were superimposed by using a surface matching software program. Ten points each on maxillary and mandibular dentures were measured for deviations after processing. Additionally, for each denture, the widths were measured between the canines and molars, the anteroposterior plane from cusp tips between the canines and molars, and the vertical plane from the cusp tip of the canines to the marginal gingiva. They were then compared with those in the denture design CAD cast. The Kruskal-Wallis analysis of variance test was used for statistical analyses (α=.05). ResultsAccording to digital superimposition, CCM had the smallest values of deviation with no statistical difference (P>.05), indicating more uniform results from measurement points in both maxillary and mandibular dentures, followed by 3DP 90M, 3DP 90, 3DP 45M, and 3DP 45. Regarding the width measurements, CCM had the smallest values of deviation (P<.05). In 3DP, smaller deviation values were observed at the vertical plane from the tip of the canine to the marginal gingiva, and larger values were observed in the intermolar width (P<.05). ConclusionsCCM exhibited smaller dimensional changes and better reproducibility among the tested techniques. In 3DP, the build angle and methods of light postprocessing influenced the dimensional stability. The 90-degree build angle with additional light polymerization on the cast improved the dimensional deviations.

3D Virtual Patient Representation for Guiding a Maxillary Overdenture Fabrication: A Dental Technique.

This report describes a technique to obtain a 3D virtual representation of a maxillary edentulous patient guided by an additively manufactured intraoral scan body. The intraoral scan body incorporated a custom tray and occlusion rim which facilitated the acquiring of a digital definitive cast, maxillary occlusion rim position, interocclusal registration, and guided the integration of the facial scans. The technique simplified the design and manufacturing of the maxillary overdenture.

Transferring occlusal vertical dimension in full arch implant prosthesis: A review

The maxillo-mandibular relationship record is a critical step to establish occlusion in implant supported full mouth rehabilitation involving fixed or removable prosthesis. The definitive implant casts have been articulated by several techniques at optimum occlusal vertical dimension (OVD) in the correct centric relation (CR) in edentulous patients receiving implants. Newer methods have been discussed for transferring vertical jaw relation that have claimed to reduce chair side time, establish accurate records and increase comfort for both, the patient and the clinician. The various techniques are, stabilized record bases with occlusal rims screwed in or supported by healing abutments, plastic sprues reinforced by acrylic record base, duplicate denture, relining existing denture, use of buccal index of existing denture and use of silicone cones. Thus, a review of the various techniques available to transfer these records onto the articulator is enlisted, from which the clinician is free to choose the technique most feasible.

ESTIMATION OF VERTICAL DISTANCE OF INCISIVE PAPILLA WITH MAXILLARY CENTRAL INCISOR AND THEIR CORRELATION IN VARIOUS ARCH FORM

Background: The relation of incisive papilla to the incisal edges of the maxillary central incisors in a vertical dimension could serve as a guide for inciso-cervical placement of anterior teeth in denture base according to the arch form of the edentulous patient. The aim of this study was to determine the vertical distance between incisive papilla and maxillary central incisor in different arch form. Methods: A cross-sectional study was conducted among 100 dentulous subjects. The vertical distance between the incisal edges of maxillary central incisor and center of incisive papilla was measured by a digital caliper on casts obtained from dentate subjects meeting inclusion criteria after which statistical analysis of data using SPSS v26 version. Results: The mean vertical distance between maxillary central incisor and incisive papilla were 5.97±1.03mm in ovoid, 6.09±0.98mm in square and 6.23±0.89mm in taper arch form. Conclusions: The result obtained in this study can be used as a clinical guideline for the fabrication of maxillary occlusal rim and may aid in determining the position of occlusal plane along with the reference of other anatomical landmarks.

POSSIBILITIES FOR MODIFICATION OF SURGICAL OBTURATOR INTO TEMPORARY OBTURATOR

Background: Maxillary resection causes different types of damages in the maxillofacial area, which are treated by surgical and prosthetic restorative methods. Aim: The described clinical case follows up the initial stages of the prosthetic treatment, as well as the possible modification of surgical obturator into temporary obturator in a patient with maxillary resection. Materials and methods: The prosthetic treatment of a 55-years-old female patient with a surgical operation of upper jaw cancer is described. The surgical obturator is developed a week after the resection. The preliminary impressions are taken with irreversible hydrocolloid impression material. The occlusion height and central relation are fixed by occlusion rims. The surgical obturator was fabricated by heat cured acrylic resin with a low amount of residual monomer. Moreover, metal clasps were used for retention and stability. The borders of the obturating part were covered with a thin layer of relining silicone material after the adjustment. The surgical obturator was modified into a temporary one directly in the patient's mouth after two months by applying the same rebasing material and designing a silicone hollow-bulb obturating part. Results: The treatment results revealed a successful restoration of the patient's speaking, feeding, and swallowing abilities. The application of silicone material inhibited the appearance of decubitus ulcers and facilitated the normal healing process. The direct design of hollow-bulb silicone obturating part significantly improved the retention and stability of the obturator. Conclusion: The application of prosthetic treatment methods in the first days after the maxillary resection allows for restoration of speaking and feeding.