Final Occlusal Research Articles

Autotransplanted premolars for substituting traumatic maxillary central incisors in a Class II growing patient

A 10-year-old young Hispanic male patient was referred to the Endodontics Department with the chief complaint of color change of maxillary central incisors. The parents reported trauma one year before and as a result root canal treatment; maxillary central incisors extractions were necessary due to poor prognosis, so he was referred to the Orthodontics Department to evaluate if the patient could be the candidate for orthodontic treatment, as he showed severe crowding. The patient had no medical conditions, and the pretreatment records showed a Class II skeletal relation and vertical pattern. Dental findings were mixed dentition, an Angle Class II molar relationship, moderate upper and lower anterior crowding, 4 mm of overbite, and 7 mm of overjet. The patient underwent autotransplantation of maxillary second premolars into the place of maxillary central incisors that needed to be extracted as stated by the endodontist (premolar extractions were needed to solve the orthodontic problems). The suggested position for the autotransplant teeth was not accomplished by the surgeon, so orthodontic forces were applied to the autotransplant teeth to the ideal position. At the end of orthodontic treatment, the autotransplanted teeth were restored by the prosthodontist. Therefore, the facial balance improved, and the final occlusal relationships were good. COVID-19 global lockdown was a challenging obstacle to overcome during treatment. This case report intends to highlight the potential benefits of tooth autotransplantation and to increase awareness of this treatment protocol.

Comparison between one-jaw and two-jaw designs in virtual surgery planning for patients with class III malocclusion

Orthognathic surgery is highly effective for treating maxillomandibular discrepancies in patients with class III malocclusion. However, whether one- or two-jaw surgery should be selected remains controversial. Our study aimed to evaluate quantitative differences between one-jaw and two-jaw surgical designs.In total, 100 consecutive patients with skeletal class III malocclusion who underwent orthognathic surgery with preoperative three-dimensional simulation between August 2016 and November 2021 were recruited. Based on the same final occlusal setup, a two-jaw surgery design and two types of one-jaw design were created. In total, 400 image sets, including preoperative images and three types of surgical simulation, were measured and compared.The one-jaw mandibular setback design led to improvement in most cephalometric measurements and facial symmetry. Although the one-jaw maxillary advancement design improved the ANB angle and facial convexity, it induced maxillary protrusion and reduced facial symmetry. Compared with the other designs, the two-jaw design provided significantly closer cephalometric measurements to the normative values, better symmetry, and less occlusal cant.Overall, the two-jaw design provided a quantitatively better facial appearance in terms of symmetry, proportion, and profile. Although an optimal surgical design necessitates thorough preoperative evaluation and a shared decision-making process, two-jaw surgery can be considered for improving overall facial esthetics and harmony.

Rehabilitation of Dentofacial Asymmetry Secondary to Unilateral Temporomandibular Joint Ankylosis with Dual Distraction and Fixed Orthodontics - Stability at Three-year Follow-up.

Optimal rehabilitation of asymmetric dentofacial deformity secondary to unilateral temporomandibular joint (TMJ) ankylosis is often a challenge. The purpose of this case series is to present an insight into esthetic, occlusal and functional rehabilitation of two patients with varying degree of asymmetric Class II dentofacial deformities secondary to long-standing unilateral TMJ ankylosis. The patients were treated with one-stage surgical protocol employing simultaneous dual distraction technique along with interpositional arthroplasty. Dual distraction technique entailed the simultaneous use of two distractors which allowed for proper control of proximal condylar segment during the course of distraction and lowering the risk of ankylosis recurrence. Thereafter, comprehensive fixed orthodontic mechanotherapy involving the use of temporary anchorage devices was instituted to align and level the compensated dentition. Post-treatment records showed significant improvements in skeletal disharmony and functional stability with good functional occlusion. At the three-year follow-up, the morphological and functionally acceptable results were reasonably well-maintained, with no signs of relapse. Through the two cases reported here, we would like to highlight that one-stage concurrent arthroplasty and dual distraction technique is a safe, stable, and reliable approach for surgical and functional rehabilitation of an adult asymmetric dentofacial deformity secondary to unilateral TMJ ankylosis. Meticulously executed comprehensive orthodontic manipulations involving use of acrylic bite-blocks, elastic traction, and temporary skeletal anchorage device play a crucial role in enhancing the final occlusal outcomes.

Assessment of the occlusal outcomes in patients treated with orthognathic surgery and clear aligners.

This retrospective two-centre study aimed to evaluate the occlusal outcomes in patients undergoing orthognathic surgery with clear aligners. A retrospective chart review and occlusal outcomes for 15 patients (10 females and five males) with different types of dentofacial deformities in the anteroposterior, vertical and transverse dimensions, who underwent orthognathic surgery in conjunction with clear aligners were evaluated. Weighed Peer Assessment Rating (PAR) index scores of the pre-treatment and post-treatment digital models were used to assess initial complexity, final occlusal outcomes and degree of improvement with surgery and clear aligners. The mean post-treatment PAR score was 3.5± 2.54, which was a statistically significant improvement from the pre-treatment PAR score of 27.63 ± 12.09, an 87% improvement was achieved. All subcategories of the PAR index showed statistically significant improvement except for midline assessment component. Occlusal outcomes with aligners showed great improvement as indicated with the PAR index scores. Orthognathic surgical cases can be treated efficiently with aligners and future studies should compare occlusal outcomes between orthognathic surgical patients treated with clear aligners and those treated with fixed appliances.

Eruption path of permanent maxillary canines after secondary alveolar bone graft in patients with nonsyndromic complete unilateral cleft lip and palate

Successful eruption of the maxillary canine after secondary alveolar bone grafting (SABG) improves dentoalveolar outcomes in the final occlusal rehabilitation of patients with cleft lip and palate (CLP). We aimed to study eruptive positions of the maxillary canine in CLP post-SABG. This retrospective longitudinal study included 27 patients with complete unilateral CLP who received standardized SABG from the same surgeon. Rigorous selection criteria enabled a relatively homogeneous sample. Using panoramic radiographs, angulation, horizontal and vertical positions of the maxillary canines were recorded 3 times. Linear proportions along with sectorial methods were used. Linear regression and t tests were performed to assess and compare the position of the canine on the cleft side (CS) and noncleft side from pre-SABG (T1) to a minimum 2 years post-SABG (T3); to evaluate its displacement and identify predictors for its impaction, and to analyze the characteristics of the impacted canines vs the nonimpacted canines at T3. The CS maxillary canine was more acutely angulated and more apically positioned than the noncleft side canine at all times. It was relatively more distally positioned at T1 and exhibited significantly greater mesial movement from T1 to T3 (P<0.0001). Canine impaction on the CS was associated with a more apical position at 1-year post-SABG (P= 0.022) and a more acute angulation of this tooth. More acute angulation and more apical position of the CS maxillary canine before SABG may be associated with an increased risk of its impaction after SABG.

Physical Versus Digital Orthognathic Surgical Planning.

Orthognathic occlusal repositioning wafers could be constructed virtually and 3D printed. This paper assessed the accuracy of a suggested virtual model to the conventionally established Glasgow model surgery. Prospective study of the orthognathic surgery models digitally. Seven patients who received bi-maxillary orthognathic surgeries for correction of dentofacial deformities. The patients were clinically assessed and their cone beam cmputerized tomography (CBCT) studied. Model surgery of each patient was performed conventionally using face-bow and semi-adjustable articulator. Same plan was executed virtually using Mimics (Materialise, Leuven, Belgium) and 3Matic (Materialise, Leuven, Belgium). Conventionally fabricated acrylic wafers as well as 3D printed wafers were CBCT scanned with the casts reflecting the archived repositioning dictated by the wafers. Paired sample t test was performed to compare accuracy between intermediate and final occlusal repositioning wafers within conventional and virtual technique groups. The mean deviation in intermediate wafer group was 0.64 ± 0.33 mm; whereas the mean deviation in final wafer group was 0.53 ± 0.10 mm. Paired sample t test showed that there was no statistically significant difference in mean deviation between both groups ( P = 0.403). This virtual surgical wafer achieves a similar level of accuracy to the conventional Glasgow model surgery.

Occlusal comparison of hand-articulation versus digital articulation in orthognathic surgery

The aim of the present study was to develop measurement methods to evaluate occlusal differences in digitally-articulated and hand-articulated models in final occlusal planning for orthognathic surgery. A total of 10 (five class II and five class III) previously treated orthognathic cases were analysed by three oral and maxillofacial surgeon investigators, creating a total of thirty cases. Investigators used physical models to create a preferred hand-held final occlusion, which were then scanned and saved utilising a Trios 3® scanner (3Shape). Models were digitally disarticulated and sent back to investigators after a period of at least a month for digital articulation. Novel measurements of dental roll, pitch, and translational differences were performed by an independent engineer using Materialise 3-Matic® software. Statistical analysis was used to evaluate translational differences, the effect of deformity, and inter-investigator variation. A mean (SD) translational difference of 1.58 mm (1.14) mm was seen between the thirty digital and hard-articulated cases analysed. Minimal difference was seen in roll and pitch between hand articulation and digital articulation. A significant translational difference was seen in class III cases compared with class II (p = 0.0006) but not in roll or pitch. There was no significant difference seen between investigators related to translation (p = 0.18), roll (p = 0.09), or pitch (p = 0.17). Digital articulation yielded similar results to hand held in this pilot study. Using measurement techniques described in larger cohorts, its accuracy can be validated using currently available technology.

Treatment Time of Class II Malocclusion, with and without Mandibular Crowding, Treated with Four Premolar Extractions: A Retrospective Study.

This study aimed to compare the treatment times in patients with complete bilateral Class II malocclusion, with and without mandibular crowding, treated with 4 premolar extractions. The sample comprised 57 retrospectively and consecutively selected patients (30 male, 27 female) treated for initial Class II malocclusion, divided as follows: Group 1 consisted of 23 patients (11 males, 12 females; mean age 13.13 years) presenting no crowding or 3 mm at most. Group 2 consisted of 34 patients (19 males, 15 females; mean age13.06 years) presenting more than 4 mm of crowding. Crowding was manually measured in the initial dental casts. The Objective Grading System (OGS) index was manually measured in the final dental casts and radiographic images. The groups were comparable regarding initial age, gender distribution, and final occlusal statuses. The treatment times between the groups were compared using the t-test. Correlation between crowding and treatment time was evaluated with Pearson correlation coefficient. Treatment times between the 2 groups were similar (P = .890) and there was no significant correlation between the amount of crowding and treatment time (r = 0.04, P = .760). Treatment times for complete Class II malocclusion with and without mandibular crowding, treated with 4 premolar extractions, are similar.

Fracture Behavior of Short Fiber-Reinforced Direct Restorations in Large MOD Cavities.

The aim of this research was to study the impact of using a short fiber-reinforced composite (SFRC) core on the fatigue performance and fracture behavior of direct large posterior composite restorations. Moreover, the influence of the consistency (flowable or packable) of occlusal composite coverage was assessed. A total of 100 intact molars were collected and randomly distributed into five groups (n = 20). Deep mesio-occlusal-distal (MOD) cavities were prepared in all groups. After adhesive treatment and rebuilding the missing interproximal walls with conventional composite, the specimens in four experimental groups were restored by an SFRC core (everX Flow), which was applied and cured either in bulk or in oblique layers (each 2 mm thick). Packable (G-aenial Posterior) or flowable (G-aenial Injectable) conventional composites were used as a final occlusal layer. The control group was restored with only packable conventional composite. Fatigue survival was measured for all specimens using a cyclic loading machine until a fracture occurred or a total of 25,000 cycles was achieved. Kaplan–Meyer survival analyses were conducted, followed by pairwise log-rank post hoc comparisons. The static load-bearing capacity of surviving teeth was tested using a universal testing machine. Fracture patterns were evaluated visually. There was no statistically significant (p > 0.05) difference in terms of survival between the tested groups. All groups for which flowable SFRC was used showed statistically significantly higher load-bearing capacities compared to the control group (p < 0.05). There were no significant differences regarding fracture resistance among the fiber-reinforced study groups. Regarding the fracture pattern during the survival analysis, all specimens that received SFRC showed a dominantly restorable type of fracture, while the control specimens presented a dominantly non-restorable type. The use of flowable SFRC as a reinforcing core for large MOD direct restorations showed promising achievements regarding fracture behavior.

A novel CAD/CAM composite occlusal splint for intraoperative verification in single-splint two-jaw orthognathic surgery

BackgroundPrevious computer-generated splints were designed and produced without modification than the traditional occlusal splints, which did not facilitate surgeon's intraoperative judgment in the single-splint two-jaw orthognathic surgery. Modifications of the digital occlusal splint can be achieved using computer-aided design and computer-aided manufacturing (CAD/CAM) software. This study reported the design, clinical application and validation of a novel CAD/CAM occlusal splint. MethodsThe maxillary and mandibular segments were fixed into the final occlusal splint and moved to the planned position according to the 3-dimensional simulation. The composite occlusal splint has 4 orthogonal bars to facilitate intraoperative assessment of the dental and skeletal midline, facial soft tissue midline, occlusal plane, upper tooth show, facial symmetry and facial bone position. To validate the surgical outcome, 5 parameters including pitch, roll and yaw rotations, midline deviation and chin position were measured on the virtual plan and the postoperative cone-beam computed tomography images to quantify the difference. ResultsThe results showed no significant differences in the 5 parameters between the simulation and postoperative images. The root-mean-square difference between the conventional splints and CAD/CAM surgical splint ranged from 0.18 to 0.31 mm by superimposition of the two image models. All patients were satisfied with the treatment outcomes. Overall, this novel occlusal splint is ideal for verification of the maxillomandibular position during surgery. ConclusionThe novel composite occlusal splint provided useful and informative check to verify the maxillomandibular complex (MMC) position and facial appearance in single-splint two-jaw orthognathic surgery.

Transmigrated mandibular canines: clinical considerations and orthodontic biomechanics for the approach of orthodontic traction. A scoping review

This scoping review aims to identify the clinical considerations and orthodontics biomechanics of applying the orthodontic traction approach to transmigrated mandibular canines. The search strategy followed the PRISMA for scoping reviews and was based on six databases, Cochrane C.R.C. Trials, BVS, PubMed (NLM), Google Scholar, Web of Science, and SCOPUS, and included articles published as recently as February 2021. The records had to identify lower canines traction protocols and outcomes. The publications obtained had to meet criteria for the structure of the research and bibliography. The search included combinations of the keywords lower canine, cuspid, and transmigration, along with the terms biomechanics and scoping review in the databases. Only after a consensus of the three reviewers had been reached were the articles retrieved. When a transmigrated lower canine has already erupted, orthodontics biomechanics traction begins by bonding tooth buttons and/or bracket prescriptions: MBT 0.022” x 0.028”, Roth 0.018” x 0.022”, and/or Beggs rectangular arches, ligatures, and elastics. Surgical interventions may be added. The treatment time varied from 22 months to 3.6 years. The final occlusal relationships were satisfactory and did not cause damage to the surrounding tissues. Among the selected articles, the orthodontic biomechanics showed the complexity of the movements. An appropriate occlusion and stability were achieved. Failures in the approach were also found. The clinical considerations show this approach to be viable but to have inherent risks, which include the proximity of the canines to the lower incisor roots.

Is a Final Splint Necessary in Bimaxillary Orthognathic Surgery?

For bimaxillary orthognathic surgery, a splint is commonly used to achieve the final occlusion and is then maintained through initial skeletal healing. The purpose of this study is to document how often a final splint is used to achieve the planned intraoperative occlusion, and how often is the final splint retained after surgery to maintain the occlusion during the initial skeletal healing phase.The investigators developed a retrospective case series. The study variables were demographic and operative. The outcome variables were the use of a final splint to achieve the desired intraoperative occlusion; the frequency and clinical indication for maintaining the final splint during the 5-weeks of initial skeletal healing; and the occlusion achieved after initial healing (5 weeks) compared to that planned from model surgery. Descriptive statistics were reported.The study sample was composed of 41 consecutive subjects. The mean age at operation was 26.9 ± 11.8 years and 51% of the subjects were male. Twenty-five subjects required segmental maxillary surgery. The final splint was used in 39% of subjects to achieve final occlusion and maintained postoperatively in only 10%. No subjects developed transverse relapse during the initial healing phase (5-weeks). All subjects with planned immediate mid-arch open-bites (n = 8) showed vertical improvement or closure during the initial healing when the splint was not maintained.The use of a final occlusal splint and then maintenance of the splint through initial skeletal healing is not required in the majority of bimaxillary orthognathic surgery cases to achieve the planned occlusion.

Use of polydioxanone suture to secure the final occlusal wafer in orthognathic surgery

Use of polydioxanone suture to secure the final occlusal wafer in orthognathic surgery

A Modified Novel Technique for Condylar Positioning in Mandibular Bilateral Sagittal Split Osteotomy Using Computer-Assisted Designed and Computer-Assisted Manufactured Surgical Guides

Current techniques for orthognathic surgery after Le Fort I osteotomy and bilateral sagittal split osteotomy (BSSO) rely on intermediate and final occlusal splints for proper positioning of the dental arches without any control in positioning the condyle and ramus segments. Setting the 2 condyles in centric relation in the glenoid fossae at fixation is paramount for condylar function and the accuracy and stability of postoperative occlusion. Usually the 2 ramus segments are manually positioned and fixated in the final position according to the surgeon's experience. This report describes a novel technique to position the condyle and ramus segments in centric relation using skeletal guides designed by computer-assisted designed and computer-assisted manufactured (CAD-CAM) technology. The skeletal guides have a double-U shape designed to be tooth borne on the distal segment and bone borne on the proximal segment. The guides fit on the last molar crown and the anterior border of the ramus; using these reference points will position the mandibular arch and 2 ramus segments in ideal centric occlusion and centric relation. The condyle position in the sagittal, horizontal, and transverse planes was analyzed by computed tomography and differences in measurements were calculated. This technique confirms precise control of the condylar segment in centric relation with stable centric occlusion using CAD-CAM guides during BSSO.

The Precision of 3D Printed CAD/CAM Occlusal Splints in Orthognathic Surgery

Purpose: To validate the accuracy of orthognathic 3D Printed final occlusal splints produced with in office desktop 3D Printer and comparing the accuracy with the conventional acrylic resin splints.Subjects & Methods: 10 Orthognathic Surgery patients were included in this study. All surgeries were performed by the same Surgeon. Computer virtual planning for Orthognathic Surgery for all cases was performed in Pro- Plan Software version 3.0 (Materialise, Leuven, Belgium) with the proper work flow ending with splint design. Final Splint with 3D Printed with an In Office Desktop Printer (Formlabs), also conventional work up was performed on all cases and acrylic resin conventional splint was fabricated. The final splints were clinically evaluated; also the 3D Printed splint image was superimposed on the virtual splint image and distance errors recorded from 3 landmarks on the upper dental model. This superimposition was repeated with the conventional splint and compared with the virtual splint and distance errors recorded. Results: All final splints (3D Printed and Conventional) accuracy was reflected as clinically acceptable. The distance error (Absolute) ranged from 0.17 – 0.82 mm and an overall mean distance error of 0.44 mm with respect to the 3D Printed splint (Final Splint2) when superimposed on the virtual design splint (Final Splint1). The distance error (Absolute) ranged from 0.26 – 0.75mm and an overall mean distance error of 0.39 mm with respect to the conventional splint when superimposed on the virtual splint (Final Splint1)Conclusion: This study has validated the accuracy of the 3D printed final splint as the mean distance error of 0.44 mm lies within the clinically acceptable range. In addition, the conventional splint design still proved highly accurate with a distance error of 0.39 mm.

Effects of supplemental vibrational force on space closure, treatment duration, and occlusal outcome: A multicenter randomized clinical trial.

A multicenter parallel 3-arm randomized clinical trial was carried out in 3 university hospitals in the United Kingdom to investigate the effect of supplemental vibratory force on space closure and treatment outcome with fixed appliances. Eighty-one subjects less than 20years of age with mandibular incisor irregularity undergoing extraction-based fixed appliance treatment were randomly allocated to supplementary (20minutes/day) use of an intraoral vibrational device (AcceleDent; OrthoAccel Technologies, Houston, Tex) (n=29), an identical nonfunctional (sham) device (n=25), or fixed-appliance only (n=27). Space closure in the mandibular arch was measured from dental study casts taken at the start of space closure, at the next appointment, and at completion of space closure. Final records were taken at completion of treatment. Data were analyzed blindly on a per-protocol basis with descriptive statistics, 1-way analysis of variance, and linear regression modeling with 95% confidence intervals. Sixty-one subjects remained in the trial at start of space closure, with all 3 groups comparable for baseline characteristics. The overall median rate of initial mandibular arch space closure (primary outcome) was 0.89mm per month with no difference for either the AcceleDent group (difference, -0.09mm/month; 95% CI, -0.39 to 0.22mm/month; P=0.57) or the sham group (difference, -0.02mm/month; 95% CI, -0.32 to 0.29mm/month; P=0.91) compared with the fixed only group. Similarly, no significant differences were identified between groups for secondary outcomes, including overall treatment duration (median, 18.6months; P>0.05), number of visits (median, 12; P>0.05), and percentage of improvement in the Peer Assessment Rating (median, 90.0%; P>0.05). Supplemental vibratory force during orthodontic treatment with fixed appliances does not affect space closure, treatment duration, total number of visits, or final occlusal outcome. NCT02314975. The protocol was not published before trial commencement. AcceleDent units were donated by OrthoAccel Technologies; no contribution to the conduct or the writing of this study was made by the manufacturer.

Accuracy of virtual surgical planning of orthognathic surgery with aid of CAD/CAM fabricated surgical splint—A novel 3D analyzing algorithm

The benefit of computer-assisted planning in orthognathic surgery has been extensively documented over the last decade. This study aims to evaluate the accuracy of a virtual orthognathic surgical plan by a novel three dimensional (3D) analysis method.Ten patients who required orthognathic surgery were included in this study. A virtual surgical plan was achieved by the combination of a 3D skull model acquired from computed tomography (CT) and surface scanning of the upper and lower dental arch respectively and final occlusal position. Osteotomies and movement of maxilla and mandible were simulated by Dolphin Imaging 11.8 Premium® (Dolphin Imaging and Management Solutions, Chatsworth, CA). The surgical plan was transferred to surgical splints fabricated by means of Computer Aided Design/Computer Aided Manufacturing (CAD/CAM). Differences of three dimensional measurements between the virtual surgical plan and postoperative results were evaluated.The results from all parameters showed that the virtual surgical plans were successfully transferred by the assistance of CAD/CAM fabricated surgical splint. Wilcoxon's signed rank test showed that no statistically significant deviation between surgical plan and post-operational result could be detected. However, deviation of angle U1 axis–HP and distance of A–CP could not fulfill the clinical success criteria. Virtual surgical planning and CAD/CAM fabricated surgical splint are proven to facilitate treatment planning and offer an accurate surgical result in orthognathic surgery.

Three-dimensional printed final occlusal splint for orthognathic surgery: design and validation

Orthognathic surgery is indicated for the treatment of significant skeletal malocclusion and is normally prepared using conventional face bows combined with two-dimensional cephalometric analysis and manually made splints. With recent developments in oral imaging, more orthognathic surgeries are being planned using three-dimensional computer-aided design and manufacturing (3D CAD/CAM) software. The purpose of this study was to present a protocol for the design and 3D printing of final digital occlusal splints based on 3D planning of orthognathic surgery and to validate the accuracy of these splints. The 3D virtual planning was performed in PROPLAN software (Materialise). The required data were then exported into 3-matic software (Materialise) to design the splints, which were 3D printed in biocompatible material using an Objet Connex 350 printer (Stratasys). To validate the accuracy of the splints, the cases of 20 patients undergoing orthognathic surgery were analysed. The splints were assessed clinically and quantitatively by comparing the printed splints to the conventional analogue set-up (clinical standard) and recording the absolute distance errors of three landmarks. The mean absolute distance error was 0.4mm (standard deviation 0.17mm), which falls within clinically accepted error margins. The absolute distance error ranged from 0.12 to 0.88mm.

Determination of final occlusal vertical dimension by cephalometric analysis

Most of techniques for determining the occlusal vertical dimension (OVD) of edentulous patients are based on soft tissues references, which lead to measurement discrepancies. Objective: To propose a method to obtain the OVD of edentulous patients during the confection of complete dentures considering the lower facial height established by Ricketts (LFHr) or the lower facial height obtained from cephalometric analysis of dentulous patients (LFHd). Material and methods: The OVD of 11 edentulous patients was determined by the association of 3 clinical methods. On each patient’s bite plates a metallic ball was fixed and the patient was submitted to lateral radiographic to obtain the lower facial height (LFHe) from cephalometric analysis. Additionally, from 40 lateral cephalograms of dentulous patients the LFHd was obtained. After that, the distance between metallic balls (DMB, in mm) was calculated to verify the linear difference when LFHe was changed to LFHd or LFHr, which provided the amount of wax to be added or removed from the bite plates, establishing a new method of OVD determination. LFHe, LFHd and LFHr values were submitted to t e z statistical tests and DMB differences were analyzed by Student’s t-test (α=0.05). Results: LFHr (47.0±4.0o a) was statistically higher than LFHd (44.9±5.6o b) and LFHe (43.5±3.5o b). There was statistical difference on linear discrepancies calculated between the LFHe and LFHd (1.7±4.1mm a) or LFHr (4.2±4.1mm b). Conclusion: The use of the cephalometric analysis showed to be a useful auxiliary tool in determining the intermaxillary relationship. However, this method must be associated with different clinical methods of OVD determination and it is recommended that regional references are used to calculate the linear discrepancies.

Occlusal evaluation and design of dental implant therapy in defect dentition

Implant prosthesis of dentition defect is characteristic of remaining teeth and implants exist at the same time, so the remaining teeth occlusal conditions related to the final occlusal design is to maintain, adjust or re-establish the original dentition occlusion. Therefore, full evaluation of remaining teeth occlusion before restoration, clear prognosis, balancing the occlusal force distribution of natural teeth and implants, and carrying out the predictable occlusal design in the entire process of implant prosthesis can minimize the adverse events after implant prosthesis. Based on the typical cases in this paper, three occlusal design types of occlusal maintain-implant restoration, occlusal adjustment-implant restoration and occlusal reconstruction-implant restoration will be expounded respectively.