Face-bow Registration Research Articles

Facially driven esthetic rehabilitation and bite elevation for a patient with worn front teeth: a case report

A facially driven rehabilitation, increasing occlusal vertical dimension (OVD) for a patient with deep bite and severely worn front teeth. Forty- year-old woman presented whose main concern was having worn maxillary and mandibular incisors, and canines. Digital smile design was applied (3Shape TRIOS Smile Design) and the upper central incisor's width-length ratio was set to 81% (initial: 100%, width: 9 mm, length: 9 mm). Following gothic arch tracing and face bow registration, OVD was increased by 3.0 mm and diagnostic wax-up (upper front- and premolar teeth; lower front-, premolar- and molar teeth) was made on casts mounted on articulator programmed to individual patient parameters. A motivational mock-up was made, followed by preparation with a minimal invasive approach. Silicone keys were used to copy the bite during optical impression taking (TRIOS 3, 3Shape) for functional digital wax-up and PMMA temporaries. After 2 months of wearing, temporaries were scanned and overlapped on a virtual model of prepared teeth using gingival, dental reference points (3Shape Dental System). Facially driven backward planning and bite elevation was performed. Monolithic final restorations (crowns, overlays, veneers) were milled (IPS e.max CAD, Ivoclar Vivadent) based on functional digital wax-up and PMMA temporaries. To reach the satisfied esthetic in the front region the presented treatment describes a conventional protocol for increasing OVD, creating a mock-up and then a digital workflow to copy the temporaries for a predictable result.

Reproducibility of Sagittal Condylar Path Inclination Assessed by Protrusive Interocclusal Record with Two Different Techniques of Facebow Registration

Purpose: The purpose is to validate whether the data obtained for sagittal condylar inclination are correctly reproduced on the semi-adjustable articulator using protrusive interocclusal records for conventional facebow registration method (orbitale (OR) as an anterior point of reference) and facebow registration using bubble leveler (BL) as an anterior point of reference and compared these values with the values obtained by lateral cephalogram (gold standard). Materials and Methods: In total, 30 individuals (20 males and 10 females) with proper teeth alignment, facebow registrations were recorded using OR as an anterior point of reference (Group A, conventional technique) and WBL as an anterior point of reference (Group B). The sagittal condylar path inclination was measured and compared using protrusive interocclusal records for both the groups. These values compared with the values for sagittal condylar path inclination obtained using lateral cephalogram (Group C) using one-way analysis of variance (P < 0.05). Results: There was no statistically significant differences observed in the values of sagittal condylar inclination for all three groups with P = 0.583. Conclusion: This study suggests that BL technique can be used for the orientation of maxillary cast on the semi-adjustable articulator as accurately as the conventional approach, for those practitioners who find difficulty in locating the OR for those patients with deformity in facial region. Lateral cephalogram provides almost the same measurements of sagittal condylar path inclination as obtained using protrusive interocclusal record on facebow registrations using OR and BL as an anterior point of references.

Does a face-bow lead to better occlusion in complete dentures? A randomized controlled trial: part I.

In a double-blinded randomized controlled clinical trial, the impact of face-bow registration for remounting complete dentures (CDs) on the occlusal parameters (part I) was evaluated. New CDs of 32 patients were duplicated and mounted after intraoral pin registration according to mean settings (group 1) and (group 2) using a face-bow (arbitrary hinge axis). The vertical dimension was reduced to the first occlusal contact point, and a bite record was fabricated in the articulator. The number of contacts and the number of teeth in contact were evaluated by a computer program (laboratory result). After randomization, half of the CDs were adjusted according to protocol of group 1 and group 2 and delivered to the patients. After 3days (T1) and 84days (T2), clinical static contact points and teeth in contact were counted. Contact points and teeth in contact of both groups (laboratory results) and at different moments (clinical results) were analyzed statistically with the F test and bootstrapping. Laboratory: No. 2 (face-bow) showed more occlusal contact points than no. 1 (mean setting), p>0.05. The number of teeth with at least one occlusal contact was significantly higher in no. 2 (p=0.027). Clinic: The mean number of teeth with at least one clinical contact point was significantly higher in no. 1 (no. 1=7.13, no. 2=5.31; p=0.042). Extent of the vertical shift poorly correlated with number of laboratory occlusal contact points (R 2=0.017). Considering the complex multistep study design, a limited number of participants, and referring to one specific arbitrary face-bow, the following conclusion could be drawn: no substantial difference by the use of the arbitrary face-bow compared to a mean setting could be determined, when changing the vertical dimension in the articulator within a remounting procedure of complete dentures. Further research is necessary to determine the effects of different arbitrary face-bows on the fabrication and adaptation of removable dentures.

Influence of a face-bow on oral health-related quality of life after changing the vertical dimension in the articulator: a randomized controlled trial. Part II.

In a double-blind randomized controlled clinical trial, the impact of face-bow registration for remounting complete dentures (CDs) on oral health-related quality of life (OHRQoL) was evaluated. New CDs of 32 subjects were clinically remounted using intraoral pin registration. CDs were transferred into a semi-adjustable articulator corresponding to group #1: mean settings with Bonwill triangle and Balkwill angle, and group #2: arbitrary hinge axis with a face-bow registration. After occlusal adjustment, subjects were followed up after 3 (T1) and 84 (T2) days. The primary outcome was the change of OHRQoL by OHIP-G49, while as secondary outcome, mucosal alterations were evaluated over time. Mean values of OHIP-G49 total sum scores and OHIP-dimensions were calculated for baseline (T0) and days 3 (T1) and 84 (T2) after intervention. Based on bootstrapping methods (changes of total OHIP sum score) and the Wilcoxon test (changes of sum scores of OHIP dimensions), analyses of between-group differences were performed. Mean values (MV) of OHIP-G49 sum scores decreased in both groups from T0 (#1 48.56; #2 45.46) to T1 (#1 31.43 (p=0.012); #2 43.20) and to T2 (#1 29.06; #2 29.40), which represents an improvement in OHRQoL. MV of OHIP-dimension sum scores decreased from T0 to T1 in both groups (#1 seven dimensions; #2 four dimensions); the decrease of sum scores was tested as not statistically significant (p>0.05). From the patient's perspective, mean-value-based remounting methods are of value. The use of a face-bow was not perceived as superior. From the patient's perspective, remounting of CDs will be positively perceived, irrespective of the use of a face-bow.

Electromagnetic navigated positioning of the maxilla after Le Fort I osteotomy in preclinical orthognathic surgery cases

Inaccuracies in orthognathic surgery can be caused during face-bow registration, model surgery on plaster models, and intermaxillary splint manufacturing. Electromagnetic (EM) navigation is a promising method for splintless digitized maxillary positioning. After performing Le Fort I osteotomy on 10 plastic skulls, the target position of the maxilla was guided by an EM navigation system. Specially implemented software illustrated the target position by real-time multistage colored three-dimensional imaging. Accuracy was determined by using pre- and postoperative cone beam computed tomography. The high accuracy of the EM system was underlined by the fact that it had a navigated maxilla position discrepancy of only 0.4mm, which was verified by postoperative cone beam computed tomography. This preclinical study demonstrates a precise digitized approach for splintless maxillary repositioning after Le Fort I osteotomy. The accuracy and intuitive illustration of the introduced EM navigation system is promising for potential daily use in orthognathic surgery.

Accuracy of Upper Jaw Positioning With Intermediate Splint Fabrication After Virtual Planning in Bimaxillary Orthognathic Surgery

The purpose of the study is to present and discuss a workflow regarding computer-assisted surgical planning for bimaxillary surgery and intermediate splint fabrication. This study describes a protocol starting from wax bite registration to fabrication of the necessary intermediate splint. The procedure is a proof of concept to replace not only the model surgery but also facebow registration and transfer from facebow to articulator. Three different modalities were utilized to obtain this goal: cone beam computed tomography (CBCT), optical dental scanning, and 3-dimensional printing. A universal registration block was designed to register the optical scan of the wax bite to the CBCT data set. Integration of the wax bite avoided problems related to artifacts caused by dental fillings in the occlusal plane of the CBCT scan. Fifteen patients underwent bimaxillary orthognathic surgery. The printed intermediate splint was used during the operation for each patient. A postoperative CBCT scan was taken and registered to the preoperative CBCT scan. The difference between the planned and the actual bony surgical movement at the edge of the upper central incisor was 0.50 ± 0.22 mm in sagittal, 0.57 ± 0.35 mm in vertical, and 0.38 ± 0.35 mm in horizontal direction (midlines). There was no significant difference between the planned and the actual surgical movement in 3 dimensions: sagittal (P = 0.10), vertical (P = 0.69), and horizontal (P = 0.83). In conclusion, under clinical circumstances, the accuracy of the designed intermediate splint satisfied the requirements for bimaxillary surgery.

Evaluation of an improved orthognathic articulator system: 1. Accuracy of cast orientation

A systematic study was carried out using plastic model skulls to quantify the accuracy of the transfer of face bow registration to the articulator. A standard Dentatus semi-adjustable articulator system was compared to a purpose built orthognathic articulator system by measuring the maxillary occlusal plane angles of plastic model skulls and of dental casts mounted on the two different types of articulators. There was a statistically significant difference between the two systems; the orthognathic system showed small random errors, but the standard system showed systematic errors of up to 28°.

A Simple and Accurate Method for Mounting Models in Orthognathic Surgery

Traditionally, a facebow device is used to register the 3-dimensional relationship of the maxillary dental arch to the Frankfort horizontal plane (FHP) using either the patient’s external meati or the condylar heads (depending on the requirements of the facebow) as the posterior reference. Auxiliary components can be attached to the facebow to aid in the anterior alignment using nasion or infraorbitale. This facebow registration is transferred to the articulator to position and mount the maxillary dental model. The mandibular dental model is then mounted with an interocclusal registration. Unfortunately, this facebow registration method often creates inaccuracies in the mounted maxillary model position, thus presenting the models in a significantly different orientation compared with the actual relationship of the patient’s jaws to the cranial base structures. 2-5 The predetermined surgical movements derived from the patient evaluation and prediction tracing, when performed on malaligned dental models, may result in significant malpositioning of the jaw structures at the actual surgery, producing compromised functional and esthetic outcomes for patients. There are reasons for inaccuracies in the traditional facebow mounting of dental models: 1) the vertical, anteroposterior (A-P), and/or mediolateral position of the patient’s external meati or condyles (depending on the reference for the facebow) may be asymmetric from side to side compared with the fixed symmetric position of the facebow mounting rods on the articulator; 2) due to anatomical variances, the patient’s FHP as determined by the facebow may be significantly different than the fixed FHP of the articulator; 3) the facebow may be improperly positioned on the patient, or facebow components could shift when tightening the bolts, nuts, and/or screws during the registration procedure; 4) cranial base and jaw aberrations may be present that are not reproducible on the articulator; 5) anatomical structures may be absent (ie, hemifacial microsomia), rendering the facebow mounting totally arbitrary; and 6) shifting of the facebow components can occur with inadequate tightening of the bolts, nuts, and/or screws at registration acquisition or with rough handling during the mounting of the maxillary model. The purpose of this article is to describe a simple and accurate method for mounting dental models using the SAM Occlusal Plane Indicator (OPI) device (Figs 1, 2) for the SAM articulator (SAM-Prazisionstechnik, Munchen, Germany: US distributor: Great Lakes Orthodontics, LTD, Tonawanda, NY). The OPI

OC6 Supportive prosthodontic therapy of HPV‐associated oral papillomas

Patient, male, 13 years old, was referred to Department of Prosthodontics, School of Dental Medicine University of Zagreb under the diagnosis of HPV‐associated oral papillomas. Oral papillomas have spread across oral cavity and were especially prominent in buccal regions. Topical treatment with interferon‐β (Fiblaferon gel®, Biosyn, Fellbach, Germany) was ordered by the Department of Oral Medicine. Papillomas on the oral aspect of cheeks were prominent and they were often injured during mastication and parafunctional activities, which included chewing on papillomas, and that facilitated their growth and made medicamentous therapy more difficult. Accordingly development of the protective occlusal splint was proposed. Alginate impressions were taken for both upper and lower jaw and stone casts were purred. Casts were mounted into SAM 2P (SAM Gmbh, Munchen, Germany) articulator using face bow registration and intercuspal jaw position. Splint was manufactured on semiresilient polyurethane foil with it's occlusal and buccal pelotes developed from self‐curing acrylate. Pelotes were designed to keep buccal mucosa away from teeth during sleep and to prevent parafunctional biting. Patient was ordered to wear splint during the night and day except when eating. Because this kind of therapy has long duration period, final results of these combined prosthodontic and medicamentous therapy will be presented.

Facts and Fallacies: An Evidence Base for Complete Dentures

The rate of edentulism is falling but many edentulous people still need complete dentures. There is poor correlation between the quality of dentures and patient satisfaction. There is no evidence that a more complex fabrication technique including face-bow registration results in a better clinical outcome. Balanced occlusion/articulation is not necessary for successful complete denture function. Variations in materials and techniques appear to have only minor influence, if any, on the clinical end result. Psychosocial factors, especially a good relationship between dentist and patient, are more important than prosthodontic factors for a positive outcome. Creating a good relationship between the dentist and the patient is extremely important for a successful outcome of a complete denture treatment.

Bite fork modification

Retention of registration material is a common problem with bite forks that are smooth and do not have retentive elements such as grooves or holes (Fig. 1). A bite fork disk was recently introduced (Bite-Tab, Panadent Corp., Grand Terrace, Calif.) that is made with standard red impression compound. The disks are attached to self: adhesive plastic strips for application and removal from the bite forks. The manufacturer states that they can be used on most standard bite forks commercially available. The Bite-Tab disk addresses the problem of retention for the face-bow registration material on this type of bite fork. This problem can be corrected without purchasing Bite-Tab disks and by drilling three 8 to 10 mm diameter holes through the bite fork (Fig. 2). The sharp edges around the holes must be rounded to prevent edge stress from brealdng the impression compound. An impression compound is heated to its worldng characteristics, placed over the holes, and a face-bow registration is made. The holes allow the impression compound to flow to the inferior surface of the bite fork. The patient's mandibular teeth can be used to stabilize the bite fork to prevent it from moving. A heavy-body polyvinyl siloxane or bite registration paste could be substituted for the impression compound.

A radiographic interpretation of cranio-facial reference lines in relation to prosthodontic plane orientation.

AbstractAn analysis was made of prosthodontically related cranio‐facial reference lines and angles of lateral skull radiographs taken for 60 edentulous Chinese adults wearing newly fabricated dentures.The radiographic angle between the Frankfort horizontal line and Camper's line was compared across Chinese and Swedish male adults. This showed a significant increase in mean angle of 3.4° for Chinese subjects. The angular difference was explained on the basis of ethnic variation in ‘orbitale’ position which could probably account for the relative steepness of the Frankfort horizontal line in the Chinese.The plane of orientation in the edentulous subject was made to conform to the ala‐tragus line. The ala‐tragus line in Chinese adults was observed radiographically to orient itself at a comparatively steep angle to the horizontal plane of the articulator.The variation in ‘orbitale’ position and the influence of a steep occlusal plane in the edentulous Chinese could impose a limit to the smooth transfer of the facebow registration of the maxillary occlusal plane to the articulator.

Registration of the condyle path inclination by intraoral wax records: Variations in three instruments

It has been asserted that intraoral registration of the condyle path inclination is so inexact that the method is of no practical value. We repeated some of Craddock's measurements using 3 subjects with complete or practically complete natural dentitions. We found a slightly smaller standard deviation than he did. Attempts were made to keep the face-bow registration and the mounting as uniform as possible. A comparison of double mountings of 3 subjects showed no statistical difference in the paired values. The differences found between different amounts of protrusion were analyzed for the single instrument and, also, in different instruments (the Dentatus and Bergström articulators and the Gnathothesiometer). This analysis was based on 10 subjects. The variations were found to be relatively large for all amounts of protrusion with all three instruments. Since the variation between instruments and amounts of protrusion is large, the reliability of a statistical analysis diminishes. However, it was possible to ascertain the following: (1) The values for 2 mm. protrusion are of an entirely different order of magnitude than those of the other amounts of protrusion. (2) The Dentatus and the Bergström articulators showed relatively good accordance with each other. (3) The unreliability of a single observation on the Gnathothesiometer is larger than for the other instruments, but the sensitivity for the readers (the difficulty of reading) and for the condyle path inclinations is lower. The main cause of the relatively large range of variation with the intraoral wax record technique is in the nature of the registration. The detail of a relatively small surface determines the positions of fairly distant points.