Vertical Occlusal Research Articles

Biomechanical Evaluation of Zygomatic Implant Versus Pterygoid Implant in Atrophic Maxilla: An In vitro Finite Element Study.

Dental implants are considered to be one of several treatment options that can be used to replace missing teeth. The objective of the study is to examine and compare the biomechanics of zygomatic and pterygoid implants planned on the atrophic maxilla with three different bone types. An in vitro finite element study was conducted on a three-dimensional model of zygomatic and pterygoid implants. In a total of 24 implants, two bilateral zygomatic and pterygoid implants with two anterior dental implants were inserted in models. 150 N vertical occlusal and 300 N load on masseter and medial pterygoid were simulated on the modeled prosthesis. The data were processed with ANSYS software. The stress on and deformations of the bones and implants were observed and compared. When comparing the D4, D3, and D2 bones in subgroup I with zygomatic implants, the D2 bone was subjected to less stress compared to D3 and D4. The smallest displacement (0.125784mm) was seen in D4 followed by the largest displacement (0.74073mm) in D2. Similarly, when comparing the D2, D3, and D4 bone in subgroup II with pterygoid implants, the D2 bone in the atrophic maxilla received the least amount of stress from the pterygoid implants compared to D3 and D4. Furthermore, the smallest displacement (0.030934mm) was seen in D2, and the largest (0.046319mm) in D4. Results suggest firstly, that the overall stress was better distributed in D2 bone and secondly, the pterygoid implant showed higher stress concentration than the zygomatic implant.

Comparison of volumetric loss and surface roughness of composite dental restorations obtained by additive and subtractive manufacturing methods

Statement of problemPermanent crown materials produced with new generation additive manufacturing and traditional subtractive manufacturing materials have not been compared in terms of wear resistance. PurposeThis study aims to compare the volumetric loss related to wear and resulting surface roughness after aging in a chewing simulator between resin nano ceramics produced with milling technique and permanent crown materials produced with three dimensional (3D) printing. Materials and methodsThree different hybrid composite-ceramic (HCC) (The three materials are GC: Cerasmart, VE: Vita Enamic, and GV: Grandio Voco.) and one 3D printed definitive crown resin (FormLabs Permanent Crown Resin) were investigated before aging (n:8), the surface roughness of all samples was measured with a profilometer, and 1 randomly selected sample from each subgroup was imaged with scanning electron microscope (SEM). 3D scans of each sample were obtained with a desktop scanner. Thermomechanical aging was performed using a chewing simulator. Four hundred thousand cycles were completed under a vertical occlusal force of 49 ± 0.7 N with a thermal cycle of 1.7 Hz 5–55° and with a dwell time of 120 s, mimicking 2 years of aging. The imaging procedures were repeated, and the change in surface roughness was evaluated. 3D images were also overlapped, and the volumetric loss was calculated with the relevant inspector software. The data obtained were analyzed by two-way ANOVA (p < 0.05). ResultThe results showed significant statistical differences for both parameters (p > 0.05). The highest volumetric loss was found in the GV group while the lowest volumetric loss was in the VE group. The highest surface roughness values were observed in the GV group, while the lowest values belonged to the VE one. ConclusionOf the restorative materials evaluated, the VE group is suitable for long-term restorations, whereas the GV one is suitable for medium-term restorations. It is promising in terms of 3D printing technologies that the 3D material gives comparable results with the GV group. Clinical i̇mplicationAdditive manufacturing techniques are a successful method that accelerates the manufacturing process. Permanent crown resins are promising alternatives to conventional production.

Vertical Occlusal Dimension Changes of Complete Dentures between Autoclave and Traditional Processing Techniques

The aim of the present in vitro study was to investigate the effect of using an autoclave with three different programs and the traditional water bath method (short cycle) on the changes in the vertical occlusal dimension of the complete acrylic dentures. Forty complete acrylic dentures were divided into four groups: G1, dentures were polymerized by water bath method (short cycle for 90 min at 74 °C and then 30 min at 100 °C); G2, dentures were polymerized with an autoclave (134 °C/2.1 bar/10 min); G3, dentures were polymerized with an autoclave (121 °C/1.1 bar/20 min); and G4, dentures were polymerized with an autoclave (121 °C/1.1 bar/5 min). The vertical occlusal dimension of the dentures was measured before and after the polymerization process. The difference between the initial and final measurements expressed the change in the vertical occlusal dimension. Data were statistically analyzed by t-test and one-way ANOVA test. Statistically significant lower vertical dimension changes were detected in G1 (0.703 ± 0.078 mm) compared to the other groups (p &lt; 0.05), whilst statistically greater changes were detected in G4 (1.263 ± 0.063 mm) compared to the other groups. No statistically significant differences were found between G2 (0.844 ± 0.061 mm) and G3 (0.88 ± 0.059 mm) (p &gt; 0.05). Within the limitations of the present in vitro study, it can be concluded that all polymerization methods increase the vertical occlusal dimension of complete acrylic dentures. The increase in the vertical occlusal dimension in Groups 1, 2 and 3 was less than 1 mm which is clinically acceptable and can be overcome by selective abrasion. Therefore, the traditional curing technique using a water bath and the autoclave methods using two settings (134 °C/2.1 bar/10 min or 121 °C/1.1 bar/20 min) could be used for the complete acrylic denture with acceptable augmentation in the vertical occlusal dimension. In contrast, the method used in G4 increases the vertical occlusal dimension by more than 1 mm, which is not clinically acceptable.

DENTINOGENESIS IMPERFECTA: A CLINICAL CASE REPORT ANTERIOR MOUTH REHABILITATION AND PUBLIC HEALTH ASPECT

The size, shape, number, and tissue structure of teeth in human dentition varies greatly. Dental conditions can run in families. Tooth discoloration caused by DI conditions can range from milky blue-gray to dark tan. Due to the weakening of the dentin structure, DI patients frequently experience severe dentition wear, missing tooth structure, missing teeth, and missing vertical occlusal dimensions. A female patient, age 39, was seen with brown tooth discoloration and wear on all of her front teeth. The patient claimed that her mother was to blame for her dental issue

Association of breastfeeding duration with the development of non-nutritive habits, and transversal and vertical occlusal alterations in preschool children: A cross-sectional study.

Breastfeeding has multiple nutritional, immunological and psychological benefits, as well as a positive influence on the development of the stomatognathic system. The present study attempted to determine the relationship between the duration of breastfeeding and the development of non-nutritive habits, and transversal and vertical occlusal alterations in preschool children. This cross-sectional study involved 155 preschoolers aged 2-5 years from 3 public schools in Lima, Peru. The sample was divided into 2 groups with regard to the duration of breastfeeding: group A (n = 50) included infants that had been breastfed for up to 6 months; and group B (n = 105) included infants that had been breastfed for 6-12 months. Two trained and calibrated dentists evaluated each group, and clinically determined the presence or absence of transversal or vertical occlusal alterations. Likewise, the children's parents or caregivers were consulted to determine the development of non-nutritive habits. A significant association was found between breastfeeding duration and the development of the oral breathing habit; groups A and B showed a prevalence of 30.0% and 16.2%, respectively (p = 0.048). Likewise, breastfeeding duration affected the appearance of oral breathing (OR (odds ratio) = 0.84; 95% CI (confidence interval): 0.74-0.96; p = 0.011). Furthermore, the use of a bottle for more than 24 months significantly influenced the appearance of oral habits (OR = 3.55; 95% CI: 1.20-10.55; p = 0.022) and open bite (OR = 12.12; 95% CI: 1.16-126.31; p = 0.037). Breastfeeding duration of 6-12 months was shown to be a protective factor in preventing the appearance of oral breathing. Posterior crossbite (PCB), open bite and deep bite seemed not to be influenced by breastfeeding duration. However, the use of a bottle for more than 24 months significantly influenced the appearance of anterior open bite.

A comparison of different methods and materials for establishing maximal intercuspal position: A clinical study

Statement of problemWhich method or material used to record the intercuspal position yields the best accuracy of location of the maxillary and mandibular casts is unclear. PurposeThe purpose of this clinical study was to determine the most reliable method of recording a patient’s maximal intercuspal position by comparing 2 common methods with 2 popular registration materials. Material and methodsComplete arch impressions were made of both jaws with a polyvinyl siloxane impression material in a metal stock tray followed by 4 interocclusal registrations for each of the 17 participants. Two registration techniques were used. More than 1 record was obtained in the first technique, as the participant had to close through a wax sheet or a polyvinyl siloxane material. In the second technique, a polyvinyl siloxane material was injected from the buccal aspect between occluded tooth surfaces. Casts were made from Type 4 stone and vertical measurements of the casts were carried out by using digital vernier calipers, accurate to 100 μm. Hand articulation of the casts was used as the control. Consistency of measurement was assessed by the intraclass correlation coefficient, and comparisons were made by using repeated-measures regression analysis. ResultsStatistical analysis showed significant discrepancies when the participant closed through both wax and polyvinyl siloxane material (P<.001). No statistically significant differences to the control group were present when polyvinyl siloxane was injected laterally after closure. ConclusionsHand articulation was the most accurate method of reproducing the maximal intercuspal position in a completely dentate individual with horizontal and vertical occlusal stability and was therefore considered the control. Recording the position after the participant had closed by using a polyvinyl siloxane material was the most accurate.

The Effect of Various Cementing Agents on Occlusal Discrepancy Using an Intra-Oral Scanner: An In Vivo Study

A marginal fit of all-ceramic crowns is a prerequisite for the long-term clinical success of a dental restoration. Few in vivo studies have investigated the effect of the film thickness of various luting agents on vertical discrepancy. This in vivo study evaluated the influence of three luting cements on the occlusal vertical discrepancy of milled crowns using a complete digital workflow. Forty-three patients treated in a students’ clinic in Tel-Aviv University with 45 single posterior digitally prepared monolithic crowns were included in the study. The crowns were randomly divided into three groups using different resin luting agents: self-adhesive resin cement, resin-modified glass ionomer cement and adhesive resin cement. The crowns were intra-orally scanned before and after cementation. The two standard tessellation language (STL) files for each crown were superimposed using digital software, and between four and six measurements were made at the occlusal surface to demonstrate the occlusal and marginal discrepancies. One-way ANOVA (α = 0.05) was used. The vertical occlusal discrepancy ranged from 2 to 38 μm. The mean vertical discrepancy values were (µm): self-adhesive resin = 12.93 ± 4.74, resin-modified glass ionomer = 19.05 ± 4.60 and adhesive resin = 13.69 ± 5.17. There were significant differences between resin-modified and self-adhesive cement groups (p = 0.004), and between resin-modified and adhesive resin cement groups (p = 0.013). Distal marginal ridge measurements were significantly different between resin-modified glass ionomer cement and self-adhesive resin cement group (p &lt; 0.001) and the adhesive resin cement group (p = 0.021). There were no significant differences between the discrepancy values at the two measurement points in the self-adhesive cement group (p = 0.377), nor the resin-modified glass ionomer group (p = 0.388), or the adhesive resin cement group (p = 0.905). The cementation procedure with various resin cements results in occlusal vertical discrepancies within standard clinical acceptability. Resin-modified glass ionomer cement produced more vertical discrepancy than adhesive and self-adhesive resin cements did.

An anterior reconstruction: increase the occlusal vertical dimension or reduce periodontal support?

Aim The aim was to document a clinical situation which was managed at minimal biological cost and with straightforward implementation. Summary Challenges of space management may arise in prosthetic dentistry as a minimum height is needed for the supporting tissues and the restorative material. While increasing the vertical occlusal dimension allows an increase in the height of the prostheses, the option may be complex and has disadvantages, including the need to modify the entire occlusion. Crown lengthening is an alternative therapeutic option, but it results in a decrease in periodontal support. Nevertheless, it allows less extensive prostheses to be provided without impacting the rest of the arch. Managing complex clinical situations with moderate biological cost and straightforward implementation is possible, as illustrated in this clinical report. Key learning points 1. Crown lengthening is a solution to increasing the tooth surfaces necessary at prosthetic rehabilitation. 2. Increasing occlusal vertical dimension (OVD) is a solution to providing the occlusal space necessary for the restorative material without reducing the supporting tissues. 3. Crown lengthening reduces periodontal support but can be considered when the root length of the affected teeth is sufficient. 4. Increasing the OVD requires modification of the entire occlusion. 5. Crown lengthening offers the advantage of not modifying OVD or intercuspal position (ICP).

Stresses in lithium disilicate crowns and zirconia implants in patients with bruxism: An in silico study

The aim of this study was to analyze by finite element analysis the influence of the use occlusal splints in rehabilitation with zirconia implant under oblique and vertical masticatory loads. Four models were developed to simulate a clinical of absence of a premolar (element 45) replaced by zirconia implant and lithium disilicate crown. Four groups were created, SP-V without occlusal splint and vertical load; CP-V with occlusal splint and vertical load; SP-O without occlusal splint and oblique load; CP-O with occlusal splint and oblique load. The four models were built using a software (SolidWorks, SolidWorks Corporation). A load of 300N to 45º (oblique) and 90º (vertical) applied to the long axis of the whole structure. The maximum principal stress (tensile) and minimum principal stress (compression), as well as the total deformation in the implant, occlusal splint, crown and bone tissue were evaluated quantitatively and qualitatively. The CP-V and CP-O groups presented the lowest stress intensities, which were homogeneously distributed in all structures analyzed. On other hand, SP-V and SP-O groups presented highest stress distributed in a heterogeneous way. Groups with occlusal splint (CP-V and CP-O) also showed lower deformation than groups without occlusal splint (SP-V and SP-O). It´s concluded the use of occlusal splint minimizes the stresses and deformation promoted by oblique and vertical occlusal loads of up 300N in implanted lithium disilicate crown supported by zirconia implants.

Considerations in occlusal vertical dimension rehabilitation

The vertical dimension is one of the important aspects that affect facial appearance, because it is related in facial height ratio. The vertical occlusal dimension is the height of the lower face measured from two points (infra-nasal and gnation points) when the maxillary and mandibular teeth were occlusion in the maximum intercuspal position. In complex cases, tooth wear can result in a decrease in facial height because the predominant wear on the anterior teeth encourages downward movement of the condyles when the intercuspal is maximum so that the vertical di-mension decreases. In addition, factors that cause a decrease in the vertical dimension are loss of posterior teeth accompanied by skeletal disharmony or accompanied by tooth abrasion and migration. The purpose of this paper is to explain how to restore the decreased occlusal vertical dimensions. Things that need to be considered are di-vided into two, extraorally and intraorally. Extraoral considerations are in the form of a large reduction in OVD, fa-cial esthetics and conditions of the temporomandibular joint. The parameters considered intraoral were the remain-ing tooth structure and occlusion. It was concluded that tooth wear due to functional and parafunctional activities can result in dimensional changes in facial morphology as well as a decrease in the occlusal vertical dimension. Correct OVD rehabilitation is an important factor in the success of rehabilitation treatment.

DÖRT FARKLI TIP ALVEOLER DEFEKTE SAHIP MAKSILLADA DÖRTLÜ ZIGOMATIK İMPLANT UYGULAMASININ BIYOMEKANIK ETKILERININ DEĞERLENDIRILMESI

Bulgular: Beş model arasında, kemikte görülen en yüksek Von Mises Stres değeri, tek taraflı kusurlu (1/3 kusurlu) maksillada bulundu. Deformasyon değeri 2/3 kusurlu maksilla modelinde en yüksek bulundu. Asimetrik defekt modellerinde, maksilla'nın sağlam kısmında daha yüksek stres değerleri elde edildi. Simetrik kusurlu modellerde, stresin daha homojen bir şekilde dağıldığı görüldü. Anahtar Kelimeler: Zigomatik implant, kuad zigoma, maksillar defekt, sonlu elemanlar analizi Evaluation of Biomechanical Effects of Quad Zigomatic Implant Applications in Four Different Maxillary Defect Types Abstract Purpose: The purpose of this study is to evaluate the biomechanical effects of quad zygomatic implant use in four different type alveolar defected maxilla. Materials and Methods: Three dimensional models of human skull, zygomatic implants, bar attachment and hybrid prosthesis was modeled using SolidWorks Computer-Aided Design (CAD) program. Four different defect locations were modeled on intact model to mimic different alveolar defect scenarios. In all models, four zygomatic implants were placed on maxilla models at the location of first premolar and second premolar tooth, assembly of the modeled parts were completed. The data were processed by ANSYS Workbench software, 150N vertical occlusal and 300N masseteric load were simulated on modeled prosthesis. The Maximum Von Mises Stress in bone/implants and deformations were visualized and comparatively evaluated with color distribution scale. Conclusion: Cortical bone thickness, defect size and localization are among the factors closely related to the stability and success of the implant. Keywords : Zygomatic implant, quadrant zygoma, maxillary defect, finite element analysis

Ontogeny of the Jaw Adductor Resultant: Using Strepsirrhine Primates as a Case Study

The masticatory system is involved in a key period in mammalian development – the transition from suckling to independent feeding. A number of biomechanically important anatomical changes occur in the masticatory system through ontogeny. Changes to the morphology of the cranium and bony jaw apparatus can modify the regions where masticatory muscles originate and insert, and can therefore alter the orientation of the masticatory muscles and how forces are directed during biting. Changes to the orientation of the masticatory muscles through ontogeny have been noted in several mammalian taxa, suggested to achieve more vertical occlusal forces (perpendicular to the bite plane) for independent feeding. In this study, we investigate if and how the orientation of the jaw adductor resultant (OJAR; the summed lines of action of the masticatory muscles) changes through ontogeny in one group of mammals, strepsirrhine primates. Given that the magnitude of a muscle vector is proportional to muscle force, we also investigate if and how the relative physiological cross‐sectional areas (PCSAs) of masticatory muscles (e.g., temporalis PCSA/total masticatory muscle PCSA) change through ontogeny.The masticatory muscles (temporalis, masseter, and medial pterygoid) of perinates, infants, juveniles, and adults from six strepsirrhine species (Eulemur macaco, Lemur catta, Lepilemur leucopus, Otolemur crassicaudatus, Propithecus coquereli, and Varecia rubra) were dissected. Muscles mass and fiber length data were then collected to estimate muscle PCSA. The OJAR (measured in degrees relative to the bite plane) was estimated using lateral photographs of dissected specimens. The relationship between the OJAR and age within species was assessed using reduced major axis regressions after natural log transforming the data. Differences in relative PCSAs of masticatory muscles (within species, through ontogeny) were evaluated using Kruskal‐Wallis tests and pairwise differences between age categories (perinate, infant, juvenile, adult) were evaluated using Conover‐Iman tests.For most species, there is a weak negative relationship (Pearson’s r = −0.10 to −0.73) between the OJAR and age. However, Otolemur crassicaudatus was found to have a weak positive relationship (Pearson’s r = 0.30). In addition, age poorly explains most of the variation in the OJAR (R2 = 0.01 to 0.53). No significant differences in relative PCSAs of masticatory muscles were found among age categories within species, except in the case of Otolemur crassicauduatus. In O. crassicaudatus, relative temporalis PCSA was found to be significantly lower in perinates than in adults (p = 0.02).These data suggest that orientation of the OJAR does not change substantially through ontogeny in strepsirrhines, and therefore does not strongly affect how forces are directed during biting in the anterior‐posterior plane. This is also supported by the lack of variation in relative PCSA of the masticatory muscles through ontogeny. This may be evidence of strong stabilizing factors in ontogeny that favor a specific direction of overall jaw adductor force at all life stages.Support or Funding InformationDuke Lemur Center Director’s Fund Award

Evaluación del conocimiento del cáncer oral en dentistas en la Región de Los Ríos, Chile, en 2017

The alteration of the vertical dimension can deteriorate the facial harmony, and it can be measured through objective and subjective methods, although many of which are not reliable. Objective: Relate the anthropometric fingers length with the measurement of the vertical occlusal dimension (VOD). Material and Methods: Cross-sectional, observational study that included 114 students from the School of Dentistry with class I malocclusion and complete dentition. The VOD was evaluated as the measurement between the subnasal points and the mental point; anthropometric measures included the length of the fingers (from the most mesial fold to the most distal edge) and the distance projected between the thumb and the index finger. Results: The average VOD was 64.03±5.15mm. A correlation was found between the VOD and the index finger length (p&lt;0.01, r=0.29), between the VOD and middle finger length (p&lt;0.01, r=0.31) and correlation between the VOD and the length of the little finger (p&lt;0.05, r=0.23). No correlation was found between the VOD and the ring finger lengths (p= 0.051) or thumb (p=0.12). Conclusions: The anthropometric measurements of the index finger, middle finger, little finger and the projection of the thumb on the index finger correlated with the length of the vertical occlusal dimension.

Biomechanical Evaluation of Zygomatic Implant Use in Patients With Different Buccal Maxillary Defect Levels.

The purpose of this study was to examine the biomechanics of zygomatic implants that were planned on an atrophic maxilla with five different buccal defect types and two different bone types. Three-dimensional models of zygomatic implants, human skulls, and maxillary prostheses were modeled with SolidWorks software. Ten finite element models of skulls with five different buccal defect types and two different bone types were constructed to mimic various clinical scenarios. Two bilateral zygomatic implants and two anterior dental implants were inserted into all models. The data were processed by ANSYS Workbench software. 150-N vertical occlusal and 300-N masseteric loads were simulated on a modeled prosthesis. The stresses on and deformations of the bones and implants were then observed and compared. Maximum Von Mises stress was found in skulls modeled with a type 4 defect and D3 bone type. Minimal stress values were found in the skull model with a type 1 buccal bone defect and D2 bone type. Displacement values were correlated with stress values. Cortical bone anchorage and bone type of zygomatic implants positively affect their biomechanics. Alveolar crest support has an effective role in the biomechanics of zygomatic implants.

Effect of Truss Access and Artificial Truss Restoration on the Fracture Resistance of Endodontically Treated Mandibular First Molars

IntroductionThis study evaluated the effects of traditional and truss access cavity preparations in addition to artificial truss restoration on the fracture resistance of endodontically treated mandibular molars. MethodsA total of 66 recently extracted, intact mandibular first molars were collected from patients between 20 and 45 years of age. After the preparation of a mesio-occluso-distal cavity in all teeth, the teeth were randomly grouped into the following 4 groups according to the access cavity design: traditional access cavity, artificial truss restoration, truss access cavity, and control groups. Endodontic access cavities were performed in the experimental groups according to each treatment modality followed by instrumentation, irrigation, and obturation. After composite restoration, the teeth were subjected to a vertical occlusal force until fracture occurred. The data were statistically analyzed, and the fracture patterns were evaluated. ResultsFirst, a 1-way analysis of variance test analysis of the fracture resistance of the experimental groups showed nonsignificant differences among groups (P > .05). Second, the data were statistically analyzed using the Student t test to compare the fracture resistance of each experimental group with that in the control group. The control group had statistically significantly higher mean values for fracture resistance than the traditional access group and the artificial truss restoration group (P < .05). No statistically significant difference was recorded in the fracture resistance between the control group and the truss access cavity group (P > .05). ConclusionsThe truss access cavity preparation improved the fracture resistance of endodontically treated teeth with mesio-occluso-distal cavities, whereas the artificial truss restoration did not improve it.

Manifestations of pain symptoms in reduced occlusion

This article presents the analysis of the relevant literature highlighting the mechanisms of the development of malocclusion and pain symptom at the reduced occlusal vertical dimension. In this case, the key complaint presented by patients is permanent steady pain described as dull, stabbing, or compressing by its character. Most often, the pain is localized within the paratoid-masticatory area as well as buccal, temporal and frontal areas, and irradiates to the upper and lower jaw or the teeth that often leads to performing unnecessary dental manipulations; to the region of the temporomandibular joint (TMJ); to the ear that sometimes is accompanied with fullness and tingling in the ears. In some cases this pain can irradiate to the hard palate and tongue. Many patients note the growing intensity of pain when chewing. Some patients experience episodic increase in pain when there are pain attacks described as compressing or stabing in the background of steady dull pain. The pain gets more intense even at the slightest movements of the head, lower jaw, or when speaking. The duration of the pain attack is approximately 20–30 minutes. A few minutes before the onset of the attack, all patients notice the emergence of somes forerunning symptoms, e.g. hyperlsalivation, paresthesia, toothache. The attacks can be provoked by conversation, overcooling, and emotional tension. It has been experimentally proven that a prolonged muscle contraction, which is often observed during emotional stress, can cause pain in the regions mentioned above. But whether will it arise or not and to what extent, it depends on the state of adaptive capacity of the body and dentofacial system. When the adaptive capacity of the body and the dentofacial system as its part are weakened, the local background for the occurrence of pain symptoms in the maxillofacial area may be: affective states (depression, anxiety), prolonged chewing load, and prolonged neck muscle tension during dental manipulations.&#x0D; Among the local factors that can cause pain, malocclusions rank the leading place. For example, a hyperbalancing contact is a sign of impaired muscle activity and coordination during the maximal closure of teeth in the lateral position of the mandible, and occlusal contacts on the balancing side affect the distribution of muscle activity during parafunctional closure, and this redistribution can impact on the temporomandibular joint (Andres K. H. et al.).&#x0D; Occlusion abnormalities may result from reduced occlusal vertical dimension, deformation of the dentitions caused by periodontal disease, partial loss of teeth, pathological tooth wearing, as well as due to improperly inserted fillings, unfit inlays, onlays, crowns.&#x0D; Reduced occlusal vertical dimension can also cause otalgia and some other otorhinolaryngological problems, pathogenesis of which is quite debatable and controversial in current literature. J. S. Costen considered hearing loss, tingling and other ear symptoms are associated with pressure produced by the head of the mandible joint onto the auditory tube. Reducing the vertical occlusal dimension results in increasing pressure of the head of the mandible joint onto the subtle bone arch of the articular fossa, which separates the cavity of the joint from the dura mater; this can trigger dull pain in the spine.&#x0D; It is important to remember that pain is a symptom that most often makes patients to search for a dental care. Pain is one of the first clinical manifestations of the body decompensation. Patients with TMJ dysfunction who experience the pain symptom is to a greater or lesser extent make up a group of patients who require a special integrated approach in their treatment.

Additional intraoral radiographs may change the judgment regarding the final position of orthodontic mini-implants.

ABSTRACTObjective: This study aimed to assess if additional vertical bitewing (VBW) and/or occlusal (OC) radiographs may change initial judgment based only on periapical radiograph (PAR) about the final position of orthodontic mini-implants (OMI). Methods: Subjective and objective analyses were performed. Radiographic images of 26 OMI were divided into four groups: PAR, PAR+VBW, PAR+OC and ALL (PAR+VBW+OC). For subjective analysis, five observers were asked to assess if the position of OMI was favorable to its success, using questionnaires with a four-point scale for responses: 1= definitely not favorable, 2= probably not favorable, 3= probably favorable, or 4= definitely favorable. Each group containing sets of images was presented to them in four different viewing sessions. Objective evaluation compared horizontal distances between OMI tip and the root nearest to the device in PAR and VBW. Results: Most of observers (3 out of 5) changed their initial judgment based on PAR about OMI position when additional radiographs were analyzed. Differences between groups (i.e. PAR vs. PAR+VBW; PAR vs. PAR+OC; and, PARvs.ALL) were statistically significant for these observers. For those that changed their judgment about OMI position, confidence level could significantly increase, decrease or even be maintained, not indicating a pattern. There was no agreement for distances between OMI tip and the root nearest to the device in PAR and VBW. Conclusion: Considering the limitations of the study, it is concluded that additional radiographic images may change the judgement about OMI final position without necessarily increasing the degree of certainty of such judgment.

Conservative oral rehabilitation of the bruxism patient with tooth wear

Tooth wear, a progressive but gradual loss of convexity on the cusp of the tooth, does not cause premature deterioration of the dentition. However, it may evolve into pathological wear if this normal wear becomes accelerated due to abnormal endogenous or exogenous factors. The pathological wear can lead to pathological changes of pulp, impaired function, occlusal disharmony and aesthetic problems. When treating patients with pathological wear, the cause of the wear must be analyzed, and each tooth should be diagnosed individually. Additionally, the loss of the vertical occlusal dimension, as well as the appropriateness of the space for restoration, should be evaluated. These procedures can prevent the progression of the wear, limit the range of any possible restoration, and finally, allow a clinician to establish a conservative treatment plan. This case report presents a patient with pathological wear caused by bruxism, and treated with monolithic zirconia fixed dental prostheses, so as to restore the lost guidance and the collapsed tooth shape; treatment was made with an occlusal adjustment of specific teeth, which showed interference during lateral excursive movement. As the result of the treatment, the functional movement of the mandible was freed, and the recurrence of tooth wear was prevented. The pathological wear displayed by this patient was successfully treated by this conservative method, as well as a limited range of restoration, all the while ensuring functionality and aesthetically satisfying results.

Implant Treatment for the Patients with Severe Deep Bite Using Screwed Denture: Technical Note

The purpose of this article is to report an innovative technique for an increase vertical dimension with screwed denture fixation and intravenous sedation for the patients with severe deep bite. Bite raising is essential to maintain a long term stability of occlusion in the case of implant treatment associated with severe deep bite. Generally, a removable denture is used to increase occlusal vertical dimension for the first step of oral rehabilitation in the case of severe deep bite. However, these patients sometimes fail wearing removable denture for increasing vertical dimension, because of severe discomfort. On the other hand, an intravenous sedation is advantage that the patients fall asleep and is completely unaware of the procedure being performed. Therefore combination screwed denture fixation and intravenous sedation allowed to raise occlusal vertical dimension in implant treatment. In conclusion, this combined method using screwed denture and intravenous sedation are the most promising technique for implant treatment to raise the vertical occlusal dimension for the patients with severe deep bite. Keywords: Severe deep bite, Screwed denture, Bite raising, Implant fracture

Finite element analysis and clinical complications in mandibular implant-overdentures opposing maxillary dentures.

Denture fracture is a common clinical complication caused by improper material selection, design, or fabrication technique. This study aimed to investigate the effect of two attachment systems on fracture risk of the implant-overdentures (IOD) via finite element analysis (FEA), using the force distributions obtained from patients' occlusal analyses and to compare the obtained results with the clinical complications associated with these attachments. A three-dimensional jaw model comprised of the edentulous bones was constructed. Three types of mandibular prostheses including complete denture (CD) (model LCD), IOD with Locator attachment (model LID-L), and IOD with telescopic attachment (model LID-T), as well as a maxillary CD (model UCD) were assembled. The vertical occlusal forces at anterior and posterior quadrants were obtained from the patients wearing mandibular CDs or IODs. The FEA results were further compared with the mechanical failures of different prostheses observed at patient recalls. In overall, the fracture risk of mandibular prostheses was lower than the maxillary compartments. The UCD opposing LCD underwent higher strains than that opposing LID-L and LID-T, which was mostly concentrated at the anterior mid-palatal polished surface. On the other hand, LID-L showed the lowest strain, followed by LID-T, and LCD. The obtained results were consistent with the clinical complications observed in the patient recalls.