Interocclusal Relationship Research Articles

Virtual bite registration using intraoral digital scanning, CT and CBCT: Invitro evaluation of a new method and its implication for orthognathic surgery.

Three-dimensional (3D) computer-assisted planning requires detailed visualisation of the craniomaxillofacial region and interocclusal relationship. The aim of this study was to establish and evaluate a method to create a 3D model of the craniomaxillofacial region and to adopt intraoral digital scanning to place the lower jaw into a centric relation (CR) without the need of additional plaster casts and model surgery. A standard plastic skull modified by metallic dental wires and brackets was subjected to computed tomography (CT), cone beam computed tomography (CBCT), and intraoral digital scanning. We evaluated two different virtual bite registrations, a digital scan of the buccal dental surfaces and scanning of the wax bites to position the lower jaw into a CR, and assessed the accuracy of the integration of intraoral scanning to the CT/CBCT scans. The mean registration error of corresponding mesh points for the CT and intraoral scanned images was 0.15±0.12mm, while this error was 0.18±0.13mm for the CBCT and intraoral scanned images. The mean accuracy of the two virtual bite registrations ranged from 0.41 to 0.49mm (buccal scan technique) and from 0.65 to 1.3mm (virtualised wax bite technique). A method for virtual bite registration was developed. It has the potential to eliminate plaster casts and model surgery and may facilitate 3D computer-assisted planning of orthognathic surgery cases.

New protocol for three-dimensional surgical planning and CAD/CAM splint generation in orthognathic surgery: an in vitro and in vivo study

Inaccurate visualization of the inter-occlusal relationship has raised an important challenge to virtual planning for orthognathic surgery based on cone beam computerized tomography (CBCT). The aim of this study was to evaluate an innovative workflow for orthognathic surgery planning and surgical splint fabrication. The clinical protocol consists of a single cone beam computerized tomography (CBCT) scan of the patient, surface scanning of the dental arches with an intraoral digital scanner, and subsequent fusion of the two datasets. The “virtual patient” thus created undergoes virtual surgery, and the resulting file with the intermediate intermaxillary relationship is used to obtain the intermediate splint by CAD/CAM technology (computer-aided design and computer-aided manufacturing). A proof-of-concept study was performed in order to assess the accuracy and reliability of this protocol. The study comprised two parts: an in vitro evaluation on three dentate skull models and a prospective in vivo assessment on six consecutive patients. Vector error calculation between the virtually simulated intermaxillary position and the intraoperative intermediate intermaxillary relationship revealed high accuracy. The greatest average variation corresponded to the y axis. Compared to previously described methods for obtaining an augmented three-dimensional virtual model, this procedure eliminates the need for dental impressions, simplifies the necessary technical steps and computational work, and reduces the patient's exposure to ionizing radiation.

Novel Oncologic, Surgical, and Prosthetic Treatment of High-Grade Surface Osteosarcoma, Osteoblastic Mandible Type

An accurate diagnosis of osteosarcoma of the jaws (OS) is determined by proper documentation and interpretation of clinical symptoms, radiologic findings, meticulous histologic survey, and a characteristic growth pattern. The characteristics of high-grade OS include a chief complaint of swelling/pain, a “fluffy” radiologic appearance with or without corticomedullary involvement, osteoblasts as the predominant cell type on histologic examination, and a highly aggressive growth pattern arising from the periosteal tissue. 1 Okada K. Unni K.K. Swee R.G. Sim F.H. High grade surface osteosarcoma: A clinicopathologic study of 46 cases. Cancer. 1999; 85: 1044 Crossref PubMed Scopus (78) Google Scholar , 2 Wold L.E. Unni K.K. Beabout J.W. Pritchard D.J. High-grade surface osteosarcomas. Am J Surg Pathol. 1984; 8: 181 Crossref PubMed Scopus (81) Google Scholar OSs of the mandible and maxilla are collectively known as gnathic osteosarcomas (GOSs) and usually exhibit long-standing pain or swelling. Emphasis on multidisciplinary oncologic, surgical, and prosthetic treatment planning of GOSs improves the treatment outcome and long-term prognosis. The treatment of GOSs, especially in the mandible, requires careful consideration of adjacent bone, soft tissue, surrounding perioral musculature, teeth, interocclusal relationships, and facial aesthetics.

Full mouth rehabilitation of mandibular edentulous patient using implant hybrid prosthesis

무치악 환자의 임플란트 보철 치료는 지지, 유지, 안정성, 발음 등의 측면에서 더 우수한 결과를 보인다. 임플란트를 이용한 무치악 환자의 치료는 다양하며, 크게 가철성과 고정성으로 나눌 수 있다. 가철성 치료에는 임플란트 유지 및 지지 피개의치가 있으며, 고정성 보철치료에는 ceramo-metal 보철물과 임플란트 하이브리드 보철물(implant hybrid prosthesis)이있다. 치료계획의 수립은 잔존 치조제, 연조직, 악간 관계, 환자의 경제적 상황 등을 종합적으로 고려하여 수립해야 한다. 임플란트를 이용한 하이브리드 보철물은 고정성 치료를 통해 환자에게 적절한 교합력을 제공하고 심리적인 안정감을 주는 동시에 적절한 연조직의 회복을 통한 심미적인 결과를 얻을 수 있다. 본 증례는 73세 여환으로 상악 Kennedy Class I 부분 무치악과 하악 무치악 상태로 내원하였다. 상악에는 우측 견치부터 좌측 제1소구치까지 7개의 잔존치를 이용한 가철성 국소의치, 하악은 양측 측절치와 제1소구치 부위에 4개의 임플란트 고정체를 이용한 하이브리드 보철물로 최종 치료 진행하였으며 치료 후 기능적, 심미적으로 만족스러운 결과를 얻었기에 이를 보고하고자 한다. 【Implant prosthodontics is beneficial for edentulous patients in enhancing the support, retention, stability, phonation and so on. Various types of prosthesis supported by implant, including implant retained- or supported- overdenture for the removable type and ceramo-metal and fixed prostheses with processed acrylic teeth for the fixed type, are frequently used. Treatment planning for the prosthesis with implant must be made after considering individual characteristics such as form of residual ridge, soft tissue, interocclusal relationship, economic status. Fixed prosthesis with processed acrylic teeth (also known as 'implant hybrid prosthesis' or 'bone anchored bridge') has the advantages of both removable and fixed prosthesis such as proper soft tissue profile, esthetic outcome, increased masticatory efficiency and psychological stability. The 73-years-old female patient came to the department of prosthodontics, Dental hospital of Yonsei University. She was diagnosed with Kennedy class I partial edentulism in the maxilla and complete edentulism in the mandible. This article reports a satisfactory clinical and esthetic outcome of full mouth rehabilitation using removable partial denture in the maxilla and implant hybrid prosthesis in the mandible.】

Interocclusal records in fixed prosthodontics

The precise relation of maxillary and mandibular casts is an essential step in developing accurate occlusion in fixed prosthodontics. When an adequate number of opposing teeth and stable intercuspation exist, direct occlusion of the casts is the most accurate method of articulation. In the absence of definitive occlusal contacts for direct relation of the casts, an interocclusal record is required. This becomes even more important when the distal tooth in the arch is also an abutment in the fixed partial denture. This article reviews various materials and techniques for recording interocclusal relationship in fixed prosthodontic procedures.

A Method for Fabrication of Implant-Supported Fixed Partial Dentures

Abstract When restoring a partially edentulous arch with an implant-supported fixed partial denture, the optimal fit and function of the final restoration depend on the fabrication of an accurate impression and the registration of the interocclusal relationship. The present case report presents a method for the fabrication of impressions and the registration of the interocclusal relationship for implant-supported partial dentures. The described method allows the accurate transfer of the implant position and the registration of the interocclusal relationship using transfer key and electroformed gold copings. The key and copings were used to transfer the intraoral implant position to the cast, to position the abutments intraorally, and to facilitate the fabrication of the final partial denture.

Insertion of Buccally Tilted and Placed Implants in Edentulous Atrophic Posterior Mandibular Sites

ABSTRACTThis paper presents our new methodology and evaluates the feasibility of buccally tilted and placed implant combined with standard abutment placement in patients with insufficient bone height through implant software programme. Forty patients with 62 mandibular sites were measured in computed tomography (CT) imaging. The Buccally tilted and placed implants combined with standard abutment simulation were administered in implant software programme. The different parameters were measured in CT. The localization of inferior alveolar nerve and implant, inclination degree of implant, transversal and vertical thickness of local distances etc. were evaluated in order to eliminate the nerve injury with providing interocclusal relationship. The buccal distance at the mandibular canal level was higher than the lingual distance in posterior mandible at lower first molar region. The mean inclination degree of the implant fixtures were 17.85 ± 8.01. The mean measurement of the acquired length of implant during implant placement simulation was 11.06 ± 1.73. The mean distance of the vertical gain was 3.81 ± 1.84. The hypothesis of buccally positioned and tilted implant placement instead of advanced surgical procedures would be preferable in atrophic posterior mandibula.

Surgical treatment of maxillary transverse deficiency: retrospective study of 14 patients

The diversity of the proposed techniques in the treatment of maxillary transverse deficiency in adults reflects the conflicting opinions about the primary area of resistance to maxillary expansion in the craniofacial skeleton. In order to evaluate the efficiency of the surgical expansion in which no osteotomies of the pterygomaxillary junction were made, we have carried out a retrospective study with 14 patients with maxillary transverse deficiency, who were treated from 2003 to 2006. In the study, models were made prior to and after surgery, and the intercanine and intermolar distances and the improvement of the interocclusal relationships were analyzed. Breathing function and the complications that occurred during and after the surgeries were also analyzed. All expansions were carried out according to pre-surgical planning so that expansion completely corrected the crossbite, resulting in the desired final occlusion for all patients. Intraoperative complications were limited to one Hyrax appliance deformation. Two patients had minor postoperative complications that included wound dehiscence and pain. Improvements in nasal breathing were observed in all patients that complained of breathing problems prior to the surgery. The satisfactory results obtained turns the surgical protocol described in this study recommended for the treatment of maxillary transverse deficiency in adults. Importantly, we found that pterygomaxillary osteotomy is not essential for maxillary expansion. The morbidity of the procedure was low with fairly minor complications, and surgically assisted rapid maxillary expansion was shown to improve nasal breathing.

An in vitro study of the effect of different occlusal registration materials on the reproducibility of mounting casts

This study compared the recorded interocclusal relationships produced using commonly used materials, determining which material accurately provides records of the interocclusal relationship for remounting. Ten occlusal registration materials were used in this study. Maxillary and mandibular casts were mounted on an articulator in maximum intercuspation. The interocclusal relationship was recorded with each specimen under a constant weight. Remounting of the mandibular cast was accomplished with the interocclusal record. The record was removed and the interocclusal contact recorded using occlusal indicator wax. The penetration of contacts was counted. This process was repeated using three specimens for each of the 10 materials used and measured. A standard deviation analysis was done on the number of penetration contacts. Stone interocclusal records were the most accurate material for occlusal registration. Wax wafer interocclusal records were the least accurate material. Clinical Application: This study suggests that the choice of material used for occlusal registration should be based on the expected time interval between occlusal registration and mounting of casts. If the mounting is expected immediately following the interocclusal registration, bite stone is the material of choice for occlusal registration. When a delay is expected between occlusal registration and mounting of the casts, non-eugenol zinc oxide may be chosen as the registration material.

A cone-beam CT based technique to augment the 3D virtual skull model with a detailed dental surface

Cone-beam computed tomography (CBCT) is used for maxillofacial imaging. 3D virtual planning of orthognathic and facial orthomorphic surgery requires detailed visualisation of the interocclusal relationship. This study aimed to introduce and evaluate the use of a double CBCT scan procedure with a modified wax bite wafer to augment the 3D virtual skull model with a detailed dental surface. The impressions of the dental arches and the wax bite wafer were scanned for ten patient separately using a high resolution standardized CBCT scanning protocol. Surface-based rigid registration using ICP (iterative closest points) was used to fit the virtual models on the wax bite wafer. Automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model. Probability error histograms showed errors of ≤0.22 mm (25% percentile), ≤0.44 mm (50% percentile) and ≤1.09 mm (90% percentile) for ICP surface matching. The mean registration error for automatic point-based rigid registration was 0.18 ± 0.10 mm (range 0.13–0.26 mm). The results show the potential for a double CBCT scan procedure with a modified wax bite wafer to set-up a 3D virtual augmented model of the skull with detailed dental surface.

The ability of different materials to reproduce accurate records of interocclusal relationships in the vertical dimension

Restorations made on incorrectly mounted casts might require considerable intra-oral adjustments to correct the occlusion or might even necessitate a remake of the restoration. The aim of this study was to evaluate interocclusal recording materials for their ability to reproduce accurate vertical interocclusal relationships after a storage time of 1 and 48 h, respectively. A custom-made apparatus was used to simulate the maxilla and mandible. Eight interocclusal records were made in each of the following groups: G1: Aluwax (aluminium wax), G2: Beauty Pink wax (hydrocarbon wax compound), G3: Futar D, G4: Futar D Fast, G5: Futar Scan (G3-G5: vinyl polysiloxane), G6: Ramitec (polyether). The vertical discrepancies were measured by an inductive displacement transducer connected to a carrier frequency amplifier after storage of the records for two periods of 1 and 48 h. Two-way anova was used for statistical analysis. The mean vertical discrepancies in mum (1/48 h) for G1 (31/35) and G2 (35/38) were statistically significantly higher than for the other groups G3 (8/10), G4 (11/12), G5 (6/8) and G6 (5/8) (P < or = 0.05). There were no statistically significant differences between the elastomers tested. The effect of storage on the vertical discrepancies was statistically significant (P < 0.001). Vinyl polysiloxane and polyether interocclusal records can be used to relate working casts during mounting procedures without significant vertical displacement of the casts.

Immediately loaded full-arch provisional implant restorations using CAD/CAM and guided placement: maxillary and mandibular case reports

This paper describes a protocol which incorporates the benefits of medical imaging, computerised virtual treatment planning, computer guided surgery, and the fitting and immediate loading of a preformed provisional full arch fixed prosthesis. The protocol can be adapted for use with the implant system of the operator's choosing and a prosthetic carrier presents the immediate load prosthesis to the mouth in its correct three-dimensional inter-occlusal relationship, simplifying the prosthetic stages for immediate load case management. Two case studies are described to illustrate the procedure for both mandibular and maxillary reconstructions.

The Use of a Wax Bite Wafer and a Double Computed Tomography Scan Procedure to Obtain a Three-Dimensional Augmented Virtual Skull Model

A detailed visualization of the interocclusal relationship is essential in a three-dimensional virtual planning setup for orthognathic and facial orthomorphic surgery. The purpose of this study was to introduce and evaluate the use of a wax bite wafer in combination with a double computed tomography (CT) scan procedure to augment the three-dimensional virtual model of the skull with a detailed dental surface. A total of 10 orthognathic patients were scanned after a standardized multislice CT scanning protocol with dose reduction with their wax bite wafer in place. Afterward, the impressions of the upper and lower arches and the wax bite wafer were scanned for each patient separately using a high-resolution standardized multislice CT scanning protocol. Accurate fitting of the virtual impressions on the wax bite wafer was done with surface matching using iterative closest points. Consecutively, automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model (Maxilim, version 2.0; Medicim NV, St-Niklaas, Belgium). Probability error histograms showed errors of < or =0.16 mm (25% percentile), < or =0.31 mm (50% percentile), and < or =0.92 (90% percentile) for iterative closest point surface matching. The mean registration error for automatic point-based registration was 0.17 +/- 0.07 mm (range, 0.12-0.22 mm). The combination of the wax bite wafer with the double CT scan procedure allowed for the setup of an accurate three-dimensional virtual augmented model of the skull with detailed dental surface. However, from a clinical workload, data handling, and computational point of view, this method is too time-consuming to be introduced in the clinical routine.

The use of a new 3D splint and double CT scan procedure to obtain an accurate anatomic virtual augmented model of the skull

Three-dimensional (3D) virtual planning of orthognathic surgery requires detailed visualization of the interocclusal relationship. The purpose of this study was to introduce the modification of the double computed tomography (CT) scan procedure using a newly designed 3D splint in order to obtain a detailed anatomic 3D virtual augmented model of the skull. A total of 10 dry adult human cadaver skulls were used to evaluate the accuracy of the automatic rigid registration method for fusion of both CT datasets (Maxilim™, version 1.3.0). The overall mean registration error was 0.1355 ± 0.0323 mm (range 0.0760–0.1782 mm). Analysis of variance showed a registration method error of 0.0564 mm ( P < 0.001; 95% confidence interval = 0.0491–0.0622). The combination of the newly designed 3D splint with the double CT scan procedure allowed accurate registration and the set-up of an accurate anatomic 3D virtual augmented model of the skull with detailed dental surface.

Occlusion recording device for dental implant-supported restorations

The accurate transfer of the interocclusal relationship is essential for providing ideal occlusion. In unilateral distal extension situations, it may be difficult to hand-articulate the casts accurately. In these instances, record bases and occlusion rims are generally fabricated. For implant-supported restorations, the record base can be screwed directly on the implant during the interocclusal recording procedure at a separate appointment. 1 Hobo S. Ichida E. Garcia L.T. Osseointegration and occlusal rehabilitation. Quintessence, Chicago1989 Google Scholar Generally, the record base is attached to the gold cylinders, 1 Hobo S. Ichida E. Garcia L.T. Osseointegration and occlusal rehabilitation. Quintessence, Chicago1989 Google Scholar the healing abutments, 2 Rungcharassaeng K. Kan J.Y.K. Fabricating a stable record base for completely edentulous patients treated with osseointegrated implants using healing abutments. J Prosthet Dent. 1999; 81: 224-227 Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar or secured with the use of impression copings. 3 Savabi O. Nejatidanesh F. Interocclusal record for fixed implant-supported prosthesis. J Prosthet Dent. 2004; 92: 602-603 Abstract Full Text Full Text PDF PubMed Scopus (9) Google Scholar The advantage of these methods is that there is no displacement of the implant during the interocclusal recording procedure, so an accurate record can be made. However, this procedure can be time consuming and requires additional visits to the dental office; furthermore, patients may experience discomfort from procedures such as the repeated removal of the healing abutments.

こう合接触関係が歯の近遠心的変化様相に及ぼす影響

To fabricate a prosthesis which is functionally harmonized with the stomatognathic system, the interocclusal relationship must be reproduced as accurately as possible. This study investigated the influence of the occlusal contacts upon tooth displacement and clarified the optimal occlusal contacts for the prosthesis. The displacement paths of six maxillary left first molars of six adults in good general health were measured in this study. We gave each test tooth eight patterns of artificial occlusal contacts by attaching platinum foil on the occlusal surface. Subjects were asked to perform clenching at the intercuspal position (= ICP) with medium occlusal forces, and 3-dimensional tooth displacement paths were measured by the Type M-3 tooth displacement transducer. The following conclusions were obtained. 1. Using the Student's t-test for statistical analysis, it was suggested that the difference of the buccolingual location of occlusal contacts influenced the direction of the tooth displacement. 2. The tooth which had occlusal contact in the buccal cusp displaced in the mesio-buccal direction, so this may create a wide dental arch and a slight discrepancy was generated at the distal interproximal contact area of the tooth. 3. It was shown that the tooth which had occlusal contact in the buccal cusp rotated in the buccoapical direction in reverse to the natural tooth.

Orthodontics. Part 3: patient assessment and examination II.

The intra-oral assessment examines the oral health, individual tooth positions and inter-occlusal relationships. When this has been completed in conjunction with the extra-oral examination, a treatment plan can then be formulated.

Clinical factors and clinical variation influencing the reproducibility of interocclusal recording methods.

The reproducibility of clinical records of the occlusion was assessed in three dimensions using mounted casts. Three distinct areas were examined: 1) mandibular positions (intercuspal position (IP) or retruded contact position (RCP)), 2) materials used in recording the occlusion, 3) clinical variation. Interocclusal records were made in a random order of three patients: one fixed prosthodontics case, one removable partial denture case and one complete denture case, with two different types of waxes, record rims, two different brands of vinyl polysiloxanes and one irreversible hydrocolloid. Private practice and Karolinska Institute, Huddinge, Sweden. One general dental practitioner and three voluntary patients. Point estimation of variance components indicate that 70-93% of the variation of the positions of the mounted casts are caused by: 1) clinical variation for all three cases and in three directions, 2) the influence of recording materials 0-29%, and 3) mandibular positions (IP/RCP) 0-11%. The ranges of the positions of the mounted casts were lower for the dentate case (0.04-1.39 mm) than for the partially dentate case (0.17-2.65 mm), which in turn was lower than those for the edentulous case (1.42-5.59 mm). Clinical variation seems to dominate the variation in positions of mounting casts when making interocclusal records, rather than mandibular position or the recording materials used. Therefore a dentist who makes one single interocclusal record cannot presume that it will reproduce the interocclusal relationship intended, which in the present study was most obvious for the edentulous case. The results showed that impression materials stabilised by a tray did not differ significantly from waxes and record rims concerning the reproducibility. Therefore the stabilised impression materials are an alternative, which also give additional advantages like reduction of appointments as well as superior accuracy.

Materials for reliable interocclusal measurements

Objective The reproducibility of clinical records of the occlusion was assessed in three dimensions using mounted casts. Three distinct areas were examined: 1) mandibular positions (intercuspal position (IP) or retruded contact position (RCP)), 2) materials used in recording the occlusion, 3) clinical variation. Design Interocclusal records were made in a random order of three patients: one fixed prosthodontics case, one removable partial denture case and one complete denture case, with two different types of waxes, record rims, two different brands of vinyl polysiloxanes and one irreversible hydrocolloid. Setting and Subjects Private practice and Karolinska Institute, Huddinge, Sweden. One general dental practitioner and three voluntary patients. Results Point estimation of variance components indicate that 70–93% of the variation of the positions of the mounted casts are caused by: 1) clinical variation for all three cases and in three directions, 2) the influence of recording materials 0–29%, and 3) mandibular positions (IP/RCP) 0–11%. The ranges of the positions of the mounted casts were lower for the dentate case (0.04–1.39 mm) than for the partially dentate case (0.17–2.65 mm), which in turn was lower than those for the edentulous case (1.42–5.59 mm). Conclusion Clinical variation seems to dominate the variation in positions of mounting casts when making interocclusal records, rather than mandibular position or the recording materials used. Therefore a dentist who makes one single interocclusal record cannot presume that it will reproduce the interocclusal relationship intended, which in the present study was most obvious for the edentulous case. The results showed that impression materials stabilised by a tray did not differ significantly from waxes and record rims concerning the reproducibility. Therefore the stabilised impression materials are an alternative, which also give additional advantages like reduction of appointments as well as superior accuracy.

IMPROVING THE QUALITY OF FIXED PROSTHODONTIC SERVICES

I have discussed only the three problems most frequently mentioned by laboratory technicians in the Lab Management Today survey. In my opinion, there are many more areas in fixed prosthodontics that need attention. To achieve this, we must improve the quality of the procedures we use in creating fixed prostheses. Laboratory technicians observe the quality of impressions, tooth preparations and interocclusal records that are sent to them by the dentists with whom they work. Their statements about the need for improvement on several of the aspects of the clinical procedure are of concern. It is dentists' professional responsibility to upgrade their clinical techniques so that they produce high-quality impressions of adequate tooth preparations and transfer information about the proper interocclusal relationship to the dental technician.