Artificial Posterior Teeth Research Articles

Comparison of anterior and posterior teeth dimensions between artificial teeth and natural dentition - An in vivo study

Background: The aesthetic and functional aspects of artificial tooth selection are pivotal for an individual's quality of life, a skill paramount to every prosthodontist. It gives a pleasing, expressive and confident life to the patient. Aim: This study aimed to juxtapose the dimensions of natural maxillary and mandibular anterior and posterior teeth with those of three commercially available denture teeth brands: Acryrock, Biorock, and Ivoclar Vivadent, taking into account gender variations Materials and Methods: Dentate casts from 23 males and 77 females were scrutinized for length and width of the natural anterior and posterior teeth dimensions. These measurements, collected by a single examiner employing a digital vernier calliper and flexible ruler, were subsequently compared to the specifications provided in the respective denture teeth mold charts. like Acryrock, Biorock, Ivoclar vivadent. The dimensions thus obtained are compared between the three systems of artificial teeth and natural teeth for selecting the best system of artificial teeth for complete denture prosthesis. Results : The study revealed that all three artificial teeth systems matched the width of natural maxillary anterior teeth. However, only the Ivoclar Vivadent teeth set closely resembled the dimensions of mandibular anterior and posterior teeth, as well as maxillary posterior teeth, across both genders. Conclusion: The findings confirm the feasibility of employing natural teeth dimensions to determine the size of anterior and posterior artificial teeth for complete denture prosthesis fabrication, providing a statistically and mathematically supported approach. keywords: artificial teeth, aesthetics, complete denture, dentulous subjects, mesiodistal width, prosthesis.

Comparison of Commercially available denture teeth with available natural teeth dimensions among genders

Background: Selecting the artificial teeth is an art, every prosthodontist should learn the art to fulfill the esthetic and functional requirement of the patient. It gives a pleasing, expressive and confident life to the patient. Aim: To compare the dimensions of natural maxillary and mandibular anterior and posterior teeth with the dimensions of three commercially available denture teeth such as Acryrock,Biorock and Ivoclar Vivadent along with gender consideration. Materials and Methods: The length and width of the natural anterior and posterior teeth from dentate casts of 23 males and 77 females were examined by a single examiner using a digital vernier caliper on a straight line and using a flexible ruler . These dimensions were also measured in three denture teeth mold charts: Acryrock, Biorock, Ivoclar vivadent. The dimensions thus obtained are compared between the three systems of artificial teeth and natural teeth for selecting the best system of artificial teeth for complete denture prosthesis. Results: This present study concludes that the width of available natural maxillary anterior teeth matches with the dimensions of all the three commercially available denture teeth such as Ivoclar Vivadent, Acryrock, Biorock. But the mandibular anterior and posterior teeth of maxillary and mandibular dentate cast dimensions were matching only with the Ivoclar vivadent teeth set irrespective of the genders. Conclusion: From this study, the determination of the size of anterior and posterior artificial teeth using the natural teeth dimensions for fabrication of complete denture prosthesis was proved statistically and mathematically.

A follow-up study of the severe occlusal surface wear of implant-supported full-arch prostheses

Objective: To evaluate the severe occlusal surface wear of implant-supported full-arch prostheses, and to explore the risk factors affecting the severe occlusal surface wear of implant-supported full-arch prostheses. Methods: Five hundred and thirty-five patients who received implant-supported fixed complete dental prostheses or implant-overdentures and completed at least one follow-up 3 months after the delivery of definitive prostheses were enrolled from October 1994 to October 2021 in this retrospective cohort study. The information on demographics, implants, definitive prostheses, and related outcomes was collected. Cox proportional hazard regression model was adopted to analyze the risk factors of the severe wear of occlusal surfaces in implant-supported full-arch prostheses. Univariate analysis was performed on the factors that may affect the severe wear of occlusal surfaces, and the parameters of P<0.10 in univariate analysis were included in multivariate analysis to explore the risk factors affecting the severe wear of occlusal surfaces in implant-supported full-arch prostheses. Results: Severe wear of the posterior occlusal surfaces was detected in 114 prostheses with a duration of 61.4 (33.3, 89.4) months. 13 cases occurred≤2 years after the delivery of definitive prostheses, 44 cases>2 years and≤5 years, 44 cases>5 years and≤10 years, and the other 13 cases>10 years. There was no significant difference in the average time of severe occlusal surface wear between implant-supported fixed complete dental prostheses and implant-overdentures in the maxilla (Z=-1.03, P=0.303). However, in the mandible, it was 48.2 (31.2, 80.2) and 79.2 (51.3, 119.1) months respectively, which was statistically significant (Z=-2.93, P=0.003). Cox proportional hazard regression model showed opposed fixed dentition, bruxism, and posterior resin occlusal surfaces were risk factors (P<0.05) affecting the severe wear of the occlusal surfaces. Conclusions: Severe occlusal surface wear was clinically common with the prolonged application of implant-supported full-arch prostheses. Prostheses opposed to fixed dentition, in patients with bruxism, and made of posterior resin materials were at higher risk of severe occlusal surface wear on the posterior artificial teeth. Regular follow-up, patients' behavior guidance, and clinicians' appropriate intervention were necessary to manage this complication.

Short-Term Crossover Study on the Effect of Orthogonalized Deep-Grooved Posterior Artificial Teeth on the Masticatory Efficiency of Complete Denture Wearers.

Background:Mastication has been regarded to play an important role in achieving quality daily life for the elderly. On the occlusal surface of posterior artificial teeth, parallel grooves of 1 mm depth and 1 mm width with an inter-groove distance of 2 mm have been found to significantly improve masticatory efficiency on a mechanical simulator. Materials and Methods:In the present study, the effect of the grooved design on masticatory efficiency in edentulous subjects using a short-term crossover trial was evaluated. Six edentulous participants, 1 male and 5 females, were assigned into two groups. One received duplicated complete dentures with grooved molars first, and the other received duplicated complete dentures with conventional molars first. The design of the teeth was crossover after evaluating masticatory efficiency. Raw carrot, raw lettuce and mixed foodstuffs were used to evaluate masticatory efficiency. Subjects were instructed to masticate 20 strokes and arbitrary strokes until they felt like swallowing.Results:The number of masticatory strokes taken was significantly smaller using the grooved design (p<.05). Masticatory efficiency analysis revealed that the grooved design achieved significantly higher masticatory efficiency at 20 masticatory strokes for raw carrot and mixed foodstuffs (p<.05).Conclusion:Results show that compared with conventional lingualized occlusion, the grooved design accomplishes higher masticatory efficiency in vivo. Considering the distinction of this design that it can be applied to any existing denture occlusion, the design might help improve the dietary life of the elderly.

Use of artificial primary teeth for endodontic laboratory research: experiments related to canal length determination

BackgroundDue to the scarcity of exfoliated/extracted human primary teeth with complete roots, artificial teeth were developed as an alternative to be used for educational and laboratory research purposes. This study aimed to assess the feasibility of using artificial primary teeth for conducting laboratory research through an experiment related to canal length determination, comparing artificial teeth with natural teeth.MethodsThirty anterior and 21 posterior artificial teeth, and the same number of natural primary teeth were selected. After preparing the access cavity, the root canal length was determined by two examiners twice using three different methods: radiography and two electronic apex locators. Then, the actual root canal length was measured by inserting a K-file up to the apical foramen (reference standard). Accuracy was calculated using Bland-Altman analysis and intraclass correlation coefficient (ICC). The inter- and intra-examiner reproducibility was also calculated using the ICC.ResultsThe methods using the electronic apex locators showed better accuracy in both artificial and natural teeth. Trends observed with artificial primary teeth were similar to those observed with natural teeth, except for the results in artificial anterior teeth.ConclusionsThe model of artificial teeth might be a good alternative for educational purposes; however, improvements are necessary to employ these teeth for research purposes when considering experiments for canal length determination.

Reinforcing effect of glass-fiber mesh on complete dentures in a test model with a simulated oral mucosa

Statement of problemStudies that evaluated the strength of complete dentures reinforced with glass-fiber mesh or metal mesh on a cast with a simulated oral mucosa are lacking. PurposeThe purpose of this in vitro study was to compare the mechanical properties of maxillary complete dentures reinforced with glass-fiber mesh with those of metal mesh in a new test model, using a simulated oral mucosa. Material and methodsComplete dentures reinforced with 2 types of glass-fiber mesh, SES mesh (SES) and glass cloth (GC) and metal mesh (metal) were fabricated. Complete dentures without any reinforcement were prepared as a control (n=10). The complete dentures were located on a cast with a simulated oral mucosa, and a load was applied on the posterior artificial teeth bilaterally. The fracture load, elastic modulus, and toughness of a complete denture were measured using a universal testing machine at a crosshead speed of 5 mm/min. The fracture load and elastic modulus were analyzed using 1-way analysis of variance, and the toughness was analyzed with the Kruskal-Wallis test (α=.05). The Tukey multiple range test was used as a post hoc test. ResultsThe fracture load and toughness of the SES group was significantly higher than that of the metal and control groups (P<.05) but not significantly different from that of the GC group. The elastic modulus of the metal group was significantly higher than that of the control group (P<.05), and no significant differences were observed in the SES and GC groups. ConclusionsCompared with the control group, the fracture load and toughness of the SES and GC groups were higher, while those of the metal group were not significantly different.

A new occlusal surface design for artificial posterior teeth to achieve high masticatory performance

PurposeThe low masticatory efficiency of denture prostheses impairs the ability of wearers to consume high-fiber foods. Hence, artificial teeth with high masticatory efficiency are required. This study aimed to establish an occlusal surface design for posterior artificial teeth in denture prostheses that is compatible with the existing artificial teeth arrangement and that has high masticatory efficiency for the comminution of raw vegetables. MethodsA masticatory simulator for occluding complete dentures was used to evaluate the masticatory efficiency of four occlusal surface designs, i.e., with parallel grooves occluding at right angles to the opposing teeth, groove depths of 1 and 0.5mm, and inter-groove distances of 1, 2, and 3mm. Raw carrots, rice, raw lettuce, chicken breasts, and peanuts were used as test foods to evaluate food comminution. ResultsGrooved occlusal surface designs with a 1-mm groove depth and a 2- or 3-mm inter-groove distance demonstrated significantly greater masticatory efficiency than the conventional occlusal form (p<0.05). ConclusionsThe superiority of grooved designs over the conventional design was particularly evident for lettuce and raw carrots in this study, both of which are considered difficult foods to chew with complete dentures.

Fracture behavior of pontics of fiber-reinforced composite fixed dental prostheses.

To evaluate the load-bearing capacities and failure mechanisms of FRC FDPs using shell-shaped acrylic denture teeth as pontics with different composite resins as filling materials. Eighty-four inlay-retained FDPs with FRC frameworks were made using shell-shaped posterior artificial teeth as pontics. Different composite resins were used as filling materials to complete the shape of the pontics. Four groups (n=21/group) were formed based on the filling material. Each group was subdivided into three subgroups and tested at 90º and 30°. Each FDP was statically loaded from the pontic until the final fracture. ANOVA revealed statistically significant differences in the load-bearing capacities according to filling material, angle and storage (p<0.01). The fracture propagated from the fiber-rich part of the pontic towards the occlusal surface of the FDP. The filling material influenced the load-bearing capacities of FRC FDPs with shell-shaped denture teeth used as pontics.

Neutrale zone. Een bij vervaardiging van volledige gebitsprothesen vaak verwaarloosde anatomische ruimte

When designing complete dentures, consideration should not only be given to the occlusal concept but also to the occlusal system as a whole. An important part of that system is the position of the artificial teeth. This prosthetic part of the occlusal system is directly related to the tongue, the floor of the mouth, the cheeks and the lips. The artificial teeth of the mandibular dentures have to be positioned in the so-called 'neutral zone' of the edentulous mandible. The neutral zone is the stress-free area between the tongue on one side and, on the other side, the mimic muscles, which are responsible for the movement of the lips and cheeks. Moreover, the maxillary posterior artificial teeth and the supporting acrylic surfaces of the maxillary denture have an important function in providing support for the upper lip and cheeks in order to prevent a 'denture look' appearance.

Condylar Paths during Protrusion in Edentulous Patients: Analysis with Electronic Axiography

The aim of this study was to determine the condylar form, incline, and movement characteristics during protrusive movement in fully edentulous complete denture wearers. The study went on to analyze the occlusal consequences on the setup of artificial posterior teeth and the occlusal grinding phase. The study included 60 complete denture wearers (aged 58 to 74 years), who received a new set of complete dentures for this study. The patients did not present signs of muscular or articular pain. Protrusive movements were recorded by a SAM(®) electronic axiography system. Condylar paths exhibited fairly specific characteristics in the completely edentulous patients, particularly path forms, which had highly specific patterns. Three condylar path forms were determined: the classic form following a convex curve (41% of cases), a sinusoidal form that flattened out in the first 2 mm before following a convex curve (51%), and a rectilinear path (9%). The mean condylar angles also exhibited specific patterns. The mean started in the first millimeter of protrusive movement, at 32.2°± 14.9°, and then increased in the second millimeter to 40.4°± 11.9°, reaching 44.5°± 9° at 5 mm. During protrusive movement in completely edentulous patients, the condylar path patterns were different than conventionally described patterns. In particular, the sinusoidal form was frequently found, and the incline of the condylar slope was low. These factors need to be taken into account during the final occlusal selective grinding for new sets of complete dentures.

Effect of ridge lap surface treatment and thermocycling on microtensile bond strength of acrylic teeth to denture base resins

This study evaluated the effect of denture base polymer type (heat- and microwave-polymerized), ridge lap surface treatment (with and without methyl methacrylate-MMA etching) and thermocycling on the microtensile bond strength (microTBS) of Biotone acrylic teeth. Flat-ground, ridge-lap surface of posterior artificial teeth were bonded to cylinders of each denture base resin, resulting in the following groups (n=6): G1a - Clássico/with MMA etching; G1b - Clássico/without MMA etching; G2a - OndaCryl/with MMA etching; G2b - OndaCryl/without MMA etching. Rectangular bar specimens with a cross-sectional area of 1 mm(2) were prepared. Half of the bars in each group were thermocycled (5,000 cycles between 4 degrees C and 60 degrees C). microTBS testing was performed in an universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by three-way ANOVA (alpha=0.05). There was no statistically significant difference (p>0.05) for the factors (resin, surface treatment,and thermocycling) or their interactions. The mean microTBS values (MPa) and standard deviations were as follows: Thermocycling - G1a: 41.00 (14.00); G1b: 31.00 (17.00); G2a: 50.00 (27.00); G2b: 40.00 (18.00); No thermocycling - G1a: 37.00 (14.00); G1b: 43.00 (25.00); G2a: 43.00 (14.00); G2b: 40.00 (27.00). The microTBS of Biotone artificial teeth to the denture base acrylic resins was not influenced by the polymer type, surface treatment or thermocycling.

義歯床下粘膜への負担圧分布からみた選択

In case of making complete dentures, we have to consider not only denture stability but also the restoration of aesthetics and function such as mastication and speech. However these are contradictory theoretically from the point of view of denture stability, and it is very difficult to satisfy both requirements in the case of a patient who has poor upper and lower alveolar ridges. We investigated the effect of artificial posterior teeth form and occlusal scheme on the distribution of pressure on supporting structures under complete dentures during mastication with upper and lower edentulous simulators. In this report, a guideline for the selection of occlusal scheme for complete dentures, based on our previous investigations, is described. The occlusal scheme remarkably affected the distribution of pressure under simulated complete dentures, as shown by comparing the distribution of pressure using two different occlusal schemes:fully balanced occlusion and lingualized occlusion. However other factors such as posterior teeth form and position affect the distribution of pressure as well, and are related to each other. Therefore, not only occlusal scheme but also posterior artificial teeth form has to be considered, and the form of posterior teeth should be carefully and comprehensively decided when making complete dentures.

Finite element analysis of the effect of the bucco-lingual position of artificial posterior teeth under occlusal force on the denture supporting bone of the edentulous patient.

To improve the quality of the complete denture prosthesis, the bucco-lingual position of the artificial posterior teeth must be determined with consideration of the shape of the maxillary and mandibular residual ridge and the relationship between them. The arrangement of posterior artificial teeth should be considered not only for the denture stability but also for the avoidance of high pressure on the supporting structures. A two-dimensional finite element method program to investigate the statics for the contour of the complete denture and the residual ridge was developed. With this program, the effect of the bucco-lingual position of the artificial posterior teeth under occlusal force on the denture supporting bone could be investigated.

臼歯部人工歯排列に考慮を要した総義歯補綴の１症例 術後７年経過症例

臼歯部人工歯排列に考慮を要した総義歯補綴の１症例 術後７年経過症例

A visual method for analysing bucco‐lingual position of artificial posterior teeth. Part 1: use of the ridge crest

We have developed a visual analysis method to examine the spatial relationship between the edentulous ridges and the bucco-lingual position of the artificial posterior teeth in complete denture fabrication. In this system, a non-contact type shape measurement system is used. We applied this system to the plaster models and the wax dentures of an edentulous patient. Using the measurement data on the upper and lower plaster models, we reconstructed their shape three-dimensionally and determined the points regarded as the ridge crests and the inter-alveolar crest lines in the frontal sections. To generate the upper and lower ridge crest lines which consisted of the points of the ridge crests, interpolation by B-spline curves was applied. Furthermore, the loft surfaces that we regarded as the consecutive inter-alveolar crest lines, were generated between the upper and lower ridge crest lines. The surface models of the plaster models and artificial teeth were displayed on the cathode-ray tube display unit, and the ridge crest lines and the consecutive inter-alveolar crest lines were superimposed on the surface models. This method could be utilized to visualize and examine the bucco-lingual position of the artificial posterior teeth in reference to the inter-alveolar crest lines.

臼歯部人工歯排列位置による上顎総義歯の動揺に関する研究

Although a lot of artificial posterior tooth positioning techniques have been proposed, correlation between complete denture stability and posterior tooth position during mastication has not yet been clarified.This study was conducted to analyze the behavior of complete maxillary dentures that have two posterior tooth positions by the simulation method. Three-dimensional mobility of these dentures was measured during biting two sizes of simulated foods on centric and eccentric positions. One of two artificial posterior teeth arrangements was based on the alveolar crest (A-denture) and the other was in a neutral zone of muscular activity (N-denture).The results were as follows:1. The working side point of two complete maxillary dentures moved downward, forward, and outward when they were loaded on one side.2. The mobility of complete maxillary dentures was changed by posterior tooth position, simulated food size, mandibular position, and tooth contact on the balancing side.3. When biting thick food, there was no tooth contact on the balancing side. In this condition, the mobility of A-denture was less than that of N-denture.4. When biting thin food, there was tooth contact on the balancing side. This contact limited the mobility of two dentures. In this condition, however, the mobility of N-denture was less than that of A-denture.

臼歯部人工歯の選択について シミュレーションモデルによる検討

The posterior artificial teeth form and occlusal scheme are the some of the important factors improving the denture stability and function. The effect of the artificial posterior teeth form and occlusal scheme on the pressure distribution on the complete denture supporting structure during simulated mastication was investigated by using upper and lower edentulous simulators. In this report, a guideline for the selection of posterior artificial teeth for complete denture, based on our previous investigation, was studied.1. The lateral wing inclination of the incisal guide table of semi-adjustable articulator, and occlusal form and scheme of posterior articulator hardly affected the pressure distribution on supporting tissues under complete denture in centric occlusion.2. When lateral mastication was simulated, the lateral wing inclination of the incisal guide table of semi-adjustable articulator, and occlusal form and scheme of posterior articulator affected the pressure distribution on supporting tissues under complete denture in centric occlusion.3. The guidelines in consideration of the denture stability were as follows:1) In the case of the patient who had good upper and poor lower alveolar ridges, full balanced occlusion with Livdent teeth should be set in his/her complete denture.2) In the case of the patient who had poor upper and lower alveolar ridged, lingualized occlusion should be set in his/her complete denture.3) In the case of the patient who had poor upper and good lower alveolar ridges, Bio-Ace teeth should be selected rather than Livdent teeth in his/her complete denture fabrication.

全部床義歯床下組織の負担圧分布に関する基礎的研究 第４報 こう合様式の差が義歯床下組織の負担圧分布に及ぼす影響

When making a complete denture, not only denture stability but also the restoration of function such as mastication and speech must be considered. The purpose of this study was to compare the pressure distribution in the supporting tissue under simulated upper and lower complete dentures using two different posterior occlusal schemes: fully balanced occlusion and lingualized occlusion.The results were as follows:1. In centric occlusion, the occlusal scheme of the artificial posterior teeth did not affect the pressure distribution under complete denture.2. In case of unilateral biting, the occlusal scheme affected the pressure distribution under complete denture with Livdent FB artificial posterior teeth, remarkably.3. In case of unilateral biting in eccentric occlusion, the occlusal scheme affected the pressure distribution. The pressure values increased on the nonworking side.It was concluded that the lingualized occlusion increases the denture stability and distributes the occlusal force to the supporting structures on the nonworking side.

全部床義歯床下組織の負担圧分布に関する基礎的研究 第３報 臼歯人工歯のこう合面形態の差が負担圧分布に及ぼす影響

In making a complete denture, the selection of the artificial posterior teeth is one of the important factors to obtain denture stability and to avoid high pressure applied to the supporting structure under a denture. The purpose of this study was to investigate the influence of the occlusal surface of the artificial posterior teeth on the pressure distribution under a complete denture.The results were as follows:1. In centric occlusion, the occlusal surface of different artificial teeth did not affect the pressure distribution under the complete denture.2. In one-side occlusion, the pressure values were changed remarkably in the buccal area on the working side and palate area as compared with the pressure distribution under the complete denture with two different artificial teeth.3. In one-side occlusion at an eccentric position, the occlusal surfaces of the artificial teeth affect the pressure distribution under the complete denture. The pressure values under the lower denture with Bio-Ace artificial posterior teeth increased on the nonworking side.

無歯顎の対向関係の診査・診断法 ３次元再構築法の利用

It is important to diagnose the maxillomandibular relation for the arrangement of artificial posterior teeth. In this study, a new method of diagnosis was developed. The contours of edentulous casts and three ball bearings and their impressions on the occlusion rims were measured by a noncontact type shape-measurement system. Using the measuring data of the casts which were interpolated by spline curves and the tentative plane of occlusion, anatomical alveolar crests were calculated. On frontal sections, the angle between the tentative plane of occlusion and the interalveolar ridge lines were calculated.The results of analysis, including anatomical alveolar crests of upper and lower casts and interalveolar ridge lines, were displayed on the CRT of a personal computer in occlusal, lateral and front views. As a result, it was suggested that this method was useful in the diagnosis of the maxillomandibular relation to edentulous casts.