|Year : 2013 | Volume
| Issue : 1 | Page : 29-34
Prosthodontic management of generalized severe dental fluorosis using simultaneous arch technique and Hobo twin-stage concept of full mouth rehabilitation
Vijay Kumar1, Harpreet Singh1, Sophia Sharma2
1 Department of Prosthodontics, M.N DAV Dental College and Hospital, Tatul, Solan, Himachal Pradesh, India
2 Department of Dental Surgery, PHU Paldi, Mahilpur, Hoshiarpur, Punjab, India
|Date of Web Publication||22-Aug-2013|
Khanpur, Mahilpur, Hoshiarpur, Punjab - 146 105
Source of Support: None, Conflict of Interest: None
Treatment of severe generalized dental fluorosis with surface defects to rehabilitate esthetics, phonetics, and mastication require removal of unsupported and pitted enamel and/or dentine, reestablishment of centric relation with or without reestablishing vertical dimension of occlusion and fabrication of full mouth crown and bridge work. In this case full occlusal reconstruction was done using simultaneous arch technique and Hobo twin-stage procedure following reorganizing approach as generalized fluorosis led to severe structural defects, oblique facets because of anterior traumatic occlusion and multiple dental caries, which were otherwise not possible to be treated by direct restorations alone. Centric relation was also recorded at reestablished vertical dimension.
Keywords: Centric relation, dental fluorosis, Hobo twin-stage procedure, removable anterior segment, simultaneous arch technique
|How to cite this article:|
Kumar V, Singh H, Sharma S. Prosthodontic management of generalized severe dental fluorosis using simultaneous arch technique and Hobo twin-stage concept of full mouth rehabilitation. SRM J Res Dent Sci 2013;4:29-34
|How to cite this URL:|
Kumar V, Singh H, Sharma S. Prosthodontic management of generalized severe dental fluorosis using simultaneous arch technique and Hobo twin-stage concept of full mouth rehabilitation. SRM J Res Dent Sci [serial online] 2013 [cited 2023 Feb 8];4:29-34. Available from: https://www.srmjrds.in/text.asp?2013/4/1/29/116826
| Introduction|| |
Dental fluorosis is a developmental disturbance of enamel caused by successive exposures to high concentrations of fluoride during tooth development.  Severely fluorosed teeth may undergo post eruptive surface breakdown and dark brown to black staining.  The enamel is often affected and may vary from areas of flecking to diffuse opacious mottling, while the color of the enamel ranges from chalky white to a dark brown/black. Brown/black discoloration may be posteruptive and probably caused by the internalization of extrinsic stain into the pitted enamel.  Appearance of teeth may also resemble line shading in pencil sketch,  which indicates dental fluorosis. This case is not common because of severe degree of damage to enamel both because of fluorosis and extensive carious lesions thus rendering it weak and fragile. Usually generalized carious lesions to such an extent are not seen in cases of generalized dental fluorosis. This necessitates extensive removal of enamel which is brittle, soft or decayed via. teeth preparation followed by extensive extracoronal restorations. Treatment of severe generalized dental fluorosis to acceptable aesthetic and mastication especially in young age remains a great challenge.
| Case Report|| |
A 22 years old male patient presented to us with generalized brown-black discoloration of teeth with multiple structural defects [Figure 1] and [Figure 2]. The patient seems to be depressed, underconfident and appear to be undernourished. Upon examination, it was also found that anterior teeth showed multiple wear facets [Figure 1]. Multiple carious lesions, pulp involvement, and chipping of enamel on applying moderate force with dental explorer were found.
The patient's dental history dated back to 12 years when he first noticed discoloration of his newly erupted upper and lower front teeth followed by involvement of subsequent erupting permanent teeth. Since then the discoloration increased to current status. There was no history of discoloration of deciduous teeth. There was positive family history of similar discoloration in his siblings as well. But there was no relevant medical history. All wisdom teeth showed irregular GAPS on cusp [Figure 3] and [Figure 4], which is an indication of dental fluorosis,  with staining in the central fossa instead of gross structural defect. Patient was diagnosed as having generalized mottling/fluorosis of teeth with brown-black staining and post eruptive dental caries. Multiple dental caries, which is not a common finding in dental fluorosis, could be a consequence of food lodgment in areas of gross enamel defects. Reverse overjet was found on left canine and premolar region. There was history of extraction of 27 and 46, nearly 7 and 1 years back, respectively, because of carious decay. Left maxillary third molar (28) probably had closed the space formed by missing 27. On extra oral examination, lower facial height was found to be normal. Lip seal was found to be incompetent.
After making diagnostic impression, two sets of diagnostic casts were made. Although extraoral appearance was not indicative of loss in vertical dimension but on intraoral evaluation based on phonetic, multiple carious decay leading to unstable and poor posterior occlusal contacts and anterior traumatic occlusion, a definitive loss in vertical dimension was found. Incompetent lip seal was probably because of short upper lip. Full mouth charting of carious teeth, missing teeth, and any alteration in occlusal plane level was done by mounting the diagnostic casts in existing centric occlusion on WhipMix articulator after making orientation record with Quickmount face bow. Maxillary cast was sectioned before mounting to get removable anterior segment. Endodontic treatment was carried out in 16, 26, 36, and 47.
Diagnostic wax-up was done on articulated diagnostic casts with removable anterior segment [Figure 5] to foresee the proposed teeth size and shape in final restorations, horizontal and vertical overlap in anterior and posterior teeth, occlusal plane and also to access modifications in teeth preparation, which were required to rectify mild rotations of teeth and reverse posterior overjet.
Teeth preparation of both the arches was done [Figure 6] utilizing information gained by diagnostic waxup, using simultaneous arch technique. Special consideration was given to 22, 24 and 36, 37 and 47 while preparation because of presence of rotation and reverse overjet relation, respectively, to bring them in class 1 relation with acceptable esthetics in final restorations within limitations. 45 and 47 were prepared to get a common path of placement for proposed porcelain fused to metal (PFM) bridge. Retraction cord was placed and impression of both arches was made using putty-wash technique. Die pins were secured to final impressions and final casts were obtained. Dies were cut to get final casts with removable dies.
Face bow record was again made using Quickmount facebow [Figure 7]. Maxillary final cast with full mouth teeth preparation was mounted on the Whip Mix articulator using Quickmount face bow. Cotton rolls were used to deprogram the masticatory muscle engrams.  Recording of centric relation requires incisal separation by 1-3 mm when the occlusal prematurities are barely separated.  As occlusal prematurities were present in this case centric relation needed to be recorded at reestablished vertical dimension. In addition to this neuromuscular relaxation is an integral part of physiologically sound and scientific centric relation recording method.  Centric relation was recorded at raised vertical dimension (approximately 23 mm) by bilateral manipulation of jaws using Anterior stop technique.  Low fusing compound was used to make anterior jig  and Addition silicone regular body (Reprosil) was used to secure the position of maxillary and mandibular posterior teeth bilaterally to complete the centric relation record , [Figure 8]. Anterior jig and two posterior records were used as tripod for relating the mandibular cast against already mounted maxillary cast to complete the articulation. Articulator values were adjusted to the average values  as advocated by Hobo for twin-stage procedure [Table 1].
This was done for reproduction of standard cusp angles and standard amount of disocclusion for Condition 1. Here posterior occlusion was developed to get balanced articulation fearlessly without considering anterior teeth as anterior segment of maxillary cast was already removed. Later anterior segment was placed back on articulator and articulator setting was changed as per Condition 2 [Table 1]. As sagittal condylar inclination for condylar path and sagittal inclination and lateral wing angle values for anterior guide table were adjusted as per Condition 2, it provides disocclusion in posterior teeth on protrusive and lateral excursions thus allowed us to develop anterior teeth occlusion without considering for amount of disocclusion produced in posterior teeth in eccentric mandibular movements.
Provisional restorations were fabricated at reestablished vertical dimension and occlusal contact relations, esthetics, and phonetics were verified in patient's mouth [Figure 9]. Provisional restorations were cemented using Temp Bond temporary luting cement. Patient was recalled after 2 weeks and examined for any discomfort in temporomandibular joints, difficulty in eating or drinking, and phonetics. Patient was found to be symptom free and he seems to regain confidence.
Castings were made with Ni-Cr alloy (Bego) and metal try in was done to access the complete seating, margin adaptation and occlusal clearance. Posterior PFM crown-bridge restorations were fabricated to develop bilateral balance occlusion without maxillary anterior teeth on articulator [Figure 10] with articulator settings for Condition 1 [Table 1]. Later anterior PFM crowns were fabricated to develop canine guidance occlusion on the articulator [Figure 11] and [Figure 12]. 36, 37, and 47 were fabricated to have cross bite relationship keeping in view their original position in dental arch. Later anterior occlusion was developed with articulator values for Condition 2 [Table 1]. Bisque trial was done in patient's mouth and verified for maximum intercuspation in centric relation and mutually protected occlusion in eccentric relations. Final restorations were cemented [Figure 13], [Figure 14], [Figure 15] and [Figure 16] with glass ionomer luting cement. Care was taken to maintain opposite occlusal contact relationship. Flash was removed after every cementation using dental explorer and dental floss.
|Figure 11: Anterior segment repositioned on articulator and all final restorations in place|
Click here to view
| Discussion|| |
Severe generalized dental fluorosis requires removal of defective and unsupported enamel, rehabilitation of mastication, phonetics, and esthetics. This becomes difficult in young patients where almost all teeth are involved to such an extent that they require some kind of extracoronal restoration for their long term survival. In addition to this, reestablishing centric relation with accuracy, when occlusal support is less in quality of quantity pose a great challenge. Moreover selection of occlusal scheme and it's effective execution add to existing challenge.
Commonly used method for treatment of mild to moderate generalized dental fluorosis is microabrasion and in-office bleaching with or without composite veneering. Microabrasion  or composite veneering was not possible for this case because of severity of damage to teeth. The final decision for selection of treatment depends upon the severity of intrinsic stains and structural defect of enamel. The reason for undertaking occlusal rehabilitation may include the restoration of multiple teeth, which are missing, worn, broken down or decayed. 
This case was treated with full mouth crown and bridge work using simultaneous arch technique as it provide us the flexibility to simultaneously restore both the arches, develop occlusal plane, occlusal scheme, crown contours, and embrasures. Reestablishing vertical dimension also provides additional space for restorative material  and esthetics result of treatment is more uniform too. Segmental technique could not be used as segmental rehabilitation of arch does not favor reestablishment of the vertical dimension. Compound anterior jig was used to exert upward and posterior guidance during mandibular closure  to reestablish the vertical dimension and recording centric jaw relation.
It was decided to develop occlusal scheme using Hobo twin-stage concept because all maxillary and mandibular anterior teeth and molars need crown-bridge work thus anterior guidance and cuspal angle can be established precisely without concern about the remaining natural teeth. Moreover, there was no abnormal curve of Spee, no severe rotations, or inclined teeth,  which cannot be straightened during the course of treatment. Twin stage procedure is based on the principles of disocclusion in lateral excursions. Here maxillary cast was cut distal to canines bilaterally, to make the anterior segment detachable. It dictates that cusp angle should be shallower than condylar path and also incisal guidance be kept steeper than condylar inclination to provide disocclusion. This provides us with a mutually protected occlusion.
| Conclusion|| |
The use of simultaneous arch technique of full mouth rehabilitation with Hobo twin-stage procedure for occlusal development has been described. Removable anterior segment of upper cast help develop occlusion of anterior and posterior teeth independent of each other. Diagnostic waxup provided vital information that helped in teeth preparation using simultaneous arch technique. Centric relation was reestablished and vertical dimension of occlusion was increased to avoid posterior occlusal prematurities and provide a comfortable position of mandible from where all functional mandibular movements could be made. For the patient described, sequence of treatment followed, appear to be effective.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16]