Clinical Management of Kennedy Class II Cases Using Osseointegrated Dental Implants

Transcription

1 Clinical Management of Kennedy Class II Cases Using Osseointegrated Dental Implants Thesis Submitted in the Partial Fulfillment of the Requirements for the Doctor Degree in Removable Prosthodontics By Ahmed Emad Eldin Hussein Fayyad B.D.S M.D.Sc.2008 (Cairo University) Faculty of Oral and Dental Medicine Cairo University 2012

2 Supervisors Prof. Dr. Samira Ibrahim Professor of Removable Prosthodontics Faculty of Oral and Dental Medicine Cairo University Dr.Ashraf Emil Eskandar Associate Professor of Removable Prosthodontics Faculty of Oral and Dental Medicine Cairo University Dr. Iman Abd-Elwahab Radi Associate Professor of Removable Prosthodontics Faculty of Oral and Dental Medicine Cairo University Faculty of Oral and Dental Medicine Cairo University 2012

3 Acknowledgment First and foremost, I am greatly thankful and grateful to Allah for granting me the chance to accomplish this work. I would like to express my most sincere gratitude and grateful appreciation to Prof. Dr. Samira Ibrahim, Professor of Prosthodontics Faculty of Oral and Dental Medicine, Cairo University. I was fortunate to conduct this work under her valuable supervision. I am deeply grateful to Dr. Ashraf Emil, Associate professor of Prosthodontics, Faculty of Oral and Dental Medicine, Cairo University for his precious help, encouragement, guidance, valuable effort and great cooperation. I am really thankful to Dr. Iman Abd-Elwahab Radi, Associate Professor of Prosthodontics, Faculty of Oral and Dental Medicine, Cairo University, who guided me in a very generous manner throughout the whole practical work. Special thanks to Prof. Dr. Khaled Zekry Professor of Prosthodontics, Faculty of Oral and Dental Medicine, Cairo University who spent every effort to spread his experience and knowledge to everyone in the department. He is been not only a professor but a father to me. I would like to thank my colleagues and all the staff members of the departement especially Dr. Amr Hosny Lecturer of Prosthodontics, Faculty of Oral and Dental Medicine, Cairo University, who continuously helped me throughout this study. Last but not least, I would like to thank my dear parents and my wife for their support throughout my studying period. i

4 List of Contents Page Acknowledgment Table of contents List of figures i ii v Introduction 1 Review of Literature: 3 I. Problems and Management of Kennedy Class II Cases: A. Problems of Kennedy class II cases: B. Proposed solutions for Kennedy class II cases II. Clinical and Radiographic Evaluation. A. Conventional imaging modalities 1. Intra-oral radiographs 2. Extra-oral radiographs B. Digital imaging modalities Extra-oral digital radiography 40 ii

5 2. Intra-oral digital radiography 42 Aim of the Study. 44 Materials and Methods. 45 Results. 83 Discussion: Discussion of methodology. Discussion of results Summary and Conclusions. 103 Bibliography 105 Arabic Summary iii

6 List of Figures Figure Page Fig. (1) Osteometer. 47 Fig. (2) Maxillary and mandibular primary impressions. 49 Fig. (3) Diagnostic set-up. 51 Fig. (4) Preoperative panoramic radiograph. 51 Fig. (5) The surgical stent with the prepared slot. 53 Fig. (6) Marking the proposed implant site. 54 Fig. (7) The crestal incision. 55 Fig. (8) The reflected flap. 55 Fig. (9) A round surgical bur used to mark the drilling site. 56 Fig. (10) Drilling of the osteotomy. 57 Fig. (11) Paralleling tool in the implant bed. 58 Fig. (12) The implant in its sterile package. 59 Fig. (13) Implant installation using a ratchet. 59 Fig. (14) Implant completely seated in place and flushed with bone. 60 Fig. (15) The healing collar screwed in place. 60 Fig. (16) Suturing of the flap. 61 Fig. (17) Milling wax. 63 Fig. (18) The milling machine. 64 Fig. (19) Milling the wax pattern of the primary coping. 65 iv

7 Fig. (20) Finishing of the metal primary coping on the milling machine. 65 Fig. (21) Checking the primary coping in the patient s mouth. 66 Fig. (22) The wax pattern of the unilateral prosthesis. 68 Fig. (23) The metal framework of the unilateral partial overdenture 69 Fig. (24) The finished unilateral partial over-denture. 69 Fig. (25) The wax pattern of the bilateral partial over-denture. 71 Fig. (26) The casted bilateral design. 72 Fig. (27) The finished bilateral partial over-denture. 72 Fig. (28) The finished bilateral partial over-denture in the patient s mouth. 73 Fig. (29) The Digora machine. 75 Fig. (30) The periapical film holder 75 Fig. (31) The radiographic template. 77 Fig. (32) A direct digital radiograph for bone level analysis. 80 Fig. (33) A direct digital radiograph for bone density analysis. 81 Fig.( 34) A line chart representing changes by time in mean bone height around the natural abutments and the implants in group I. 86 Fig.( 35) A line chart representing changes by time in mean bone height around the natural abutments and the implants in group II. 87 v

8 Fig.( 36) A bar chart representing the mean amount of bone loss around the natural abutments and the implants in the two groups. 89 Fig.( 37) A line chart representing changes by time in mean bone density around the natural abutments and the implants in group I. 90 Fig.(38) Fig.(39) A line chart representing changes by time in mean bone density around the natural abutments and the implants in group II. A bar chart representing the mean % increase in bone density around the natural abutments and the implants of the two groups vi

9 List of Tables Table. (1) Patient satisfaction. 83 Page Table. (2) Table. (3) Table. (4) Mean marginal bone level measurements for the natural teeth and the implants in both groups. The mean values, standard deviation (SD) values and results of paired t-test by time for mean bone level changes around the implants and natural teeth of group I The mean values, standard deviation(sd) values and results of paired t-test by time in mean bone level around implants and the natural abutments of group II Table. (5) The mean bone loss, standard deviation (SD) values and results of Mann-Whitney U test for comparison between the two groups. 88 Table. (6) The mean difference, standard deviation (SD) values and results of paired t-test for the change by time in mean bone density around the natural abutments and the implants of group I. 90 Table. (7) The mean difference, standard deviation(sd) values and results of paired t-test for the change by time in mean bone density around the natural abutments and the implants of group II. 91 Table. (8) The mean %, standard deviation (SD) values and results of Mann-Whitney U test for comparison between the two groups. 93 vii

10 Introduction Different treatment modalities have been proposed for the management of distal extension cases. However, controversy exists about the most suitable line of treatment that can satisfy the patient's needs. The challenge in unilateral distal extension cases is even more than the bilateral ones. This is because in most of the cases restored with a conventional partial denture, the patient is not satisfied because of comparing it with the intact side. Generally speaking, problems of distal extension base partial dentures are mainly due to the absence of posterior abutments and the difference in support between the periodontal ligament of the abutment tooth and the mucoperiosteum covering the edentulous ridge. This causes the denture base to rotate under loading, thereby exerting excessive torque on the abutment teeth leading to their early loss (Holmes, 2001). Various design concepts were suggested to solve the problem of unilateral distal extension cases, among which is the use of osseointegrated dental implants, thus converting the distal extension base removable partial denture from a tooth-tissue supported prosthesis with its problems into a tooth-implant-supported one ( Jang et al., 1998). Even a single implant placed in a strategic position provides indefinite range of options for removable prosthesis with high success rates (Krennmair et al., 2007). Telescopic crown retained removable partial denture is one of the options which provides satisfactory support and retention together with preservation of the surrounding supporting structures. Applying the concept of simplifying the design dictates a unilateral partial denture for class II cases. This design could be more easily accepted by the patients. However, 1

11 Introduction extension of the prosthesis to the other side for the purpose of cross arch stabilization has been recommended by many authors (Krennmair et al., 2007). Now a question arises, which is better, to construct a unilateral design which is usually accepted by the patients or a bilateral design keeping in mind to preserve the health of the supporting structures? 2

12 Review of Literature I. Problems and Management of Kennedy Class II Cases: A. Problems of Kennedy class II cases: Brudvic (1999) stated that the problems associated with the Kennedy class II (unilateral free end saddle) partial dentures are support, poor stability, and minimal retention. These problems are attributed to the lack of distal tooth support, in addition to the difference in resiliency between the mucoperiosteum and the periodontal ligament. The lever action resulting from this difference are potentially destructive to the abutments and the surrounding tissues (Cunha et al., 2008). 1. Support: Support is defined as the quality inherent in the dental prosthesis acting to resist the displacement towards the basal tissues or underlying structures (The Academy of Proshodontics, 2005). It is the major problem in the distal extension base removable partial dentures. Due to the absence of the posterior abutment, the partial denture shares its support between the teeth and the edentulous ridge, which differs markedly in the viscoelastic response to loading. The mucosa covering the edentulous ridge is much more easily displaced than the periodontal ligament of the abutment teeth and has a slower rate of recovery that may extend to several hours. The difference in displacement between the mucosa and the periodontal ligament was 3

13 Review of Literature estimated to be up to13 times (Holmes, 2001 and Kuzmanovic et al. 2004). Consequently, when functional pressure is applied to the distal extension base removable partial dentures, it moves towards the mucosal tissues and rotates around the fulcrum line connecting the two main occlusal rests, with the greatest movement taking place at the most posterior extent of the denture base. The resultant rotational forces are extremely damaging to the abutment teeth and must be controlled if clinical treatment is to be successful (Carr and Brown, 2011). 2. Retention: Retention is defined as the quality inherent in the dental prosthesis acting to resist the forces of dislodgment along the path of placement (The Academy of Proshodontics, 2005). It was reported that retention which can be obtained mechanically by placing retaining elements on the abutment teeth is termed primary retention. On the other hand, secondary retention depends on physical means and frictional resistance which is provided by the intimate contact of minor connectors with the guiding plane, denture base and major connectors with the underlying tissues. The secondary retention is proportionate to the accuracy of the impression technique, accuracy of denture base fit and the total area of contact involved (Carr and Brown, 2011). 4

14 Review of Literature Retaining elements could be either attachments or clasps. Various designs of intracoronal and extracoronal attachments were suggested for retaining the distal extension base removable partial denture. It was found that attachments were more advantageous than clasp-retained removable partial dentures since they provide superior esthetics, better retention and distribution of occlusal forces to the supporting structures (Saito et al., 2003). Among the suggested attachments are conical crown telescopic retainer which was found to provide a stable occlusion during function offering adequate retention without subjecting the abutment teeth to excessive tourqing. However, almost 80% of the load is borne by the abutment teeth, which could jeopardize the health of their periodontium (Saito et al., 2003). Davenport et al. (2005) mentioned that, muscular control of the tongue and the cheek is of importance for retention and success of lower free end saddle dentures. 3. Stability and Bracing: Stability is defined as the quality of the removable dental prosthesis to be firm and steady to resist displacement by functional horizontal or rotational stresses, while bracing is defined as the quality of a removable dental prosthesis that resists horizontal component of masticatory forces (The Academy of Proshodontics, 2005). As mentioned earlier, the distal extension base removable partial denture rotates when forces are applied to the denture base. Since it can be assumed that 5

15 Review of Literature this rotation may create horizontal and lateral forces, the presence of stabilizing components in proper relation to the horizontal axis of the abutment teeth becomes important. Several components play a role in stabilizing the removable partial denture, among which are the minor connectors and guiding planes, all play a role in counteracting the lateral forces falling on the partial denture and in preventing its horizontal shift. Furthermore, in distal extension base removable partial dentures, it is advisable to provide cross-arch stabilization by placing a rigid clasp on the intact side of the arch (Phoenix et al., 2003). The maximum coverage by the denture base minimizes the lateral forces on the remaining structures, providing additional resistance to horizontal movement. Moreover, stabilizing elements must distribute stresses equally on all supporting teeth without overstressing any tooth (Mitrani et al., 2003). B. Proposed solutions for the Kennedy class II cases: Arslan et al. (2006) and D'Sauza and Dua (2011) stated that rehabilitation of a partially edentulous patient can be established using a wide range of prosthetic treatment options. Depending upon the clinical needs and demands, restoration of the lost structures can be achieved by using simple conventional clasp retained removable partial denture, attachment retained removable partial denture, partial overdenture, fixed partial denture or dental implants. An orthodontic solution for unilateral free end saddle cases was also proposed. Recently tissue engineering was proposed as an alternative solution for the problem. 6

16 Review of Literature The different treatment modalities of restoring partially edentulous cases aimed to improve the masticatory function and esthetics, to restore the posterior occlusal support and vertical dimension of occlusion, and to avoid compromising the patient s oral health (Grossmann et al., 2009). 1. Conventional clasp retained removable partial denture: In the past, the clasp retained removable partial denture was the conventional and most commonly used method in restoring a unilateral free end saddle case (Carr and Brown 2011). Carr and Brown (2011) claimed that construction of a clasp retained removable partial denture is easier, less time consuming, less expensive and requires less technical skills than other restorations. A well designed clasp-retained removable partial denture can restore function effectively and can aid in preservation of the remaining natural teeth and tissues. However, it has some disadvantages. Clasps are often unaesthetic, caries may develop beneath clasp components, and if improperly designed it will produce adverse effect on the abutments and the other supporting structures. In a conventional removable partial denture, problems of Kennedy class II could be reduced or eliminated by taking the following into consideration: a. Occlusal load reduction: It has been suggested that reduction of the load transmitted, whether vertical or lateral, to the supporting structures could be achieved through maximum denture base extension, using canines and premolars instead of 7

17 Review of Literature molars, leaving a tooth off the base, decreasing the size of the occlusal table width, development of balanced harmonious occlusion, placing the artificial teeth over the center of the ridge crest and reduction of the cusp angles (Book et al., 1992 and Carr and Brown, 2011). This also was proved by Rodrigues et al., 2002 who stated that the use of resilient layer situated between the artificial teeth and the denture base can act as an effective shock absorber that reduces the magnitude of the forces exerted upon the supporting structures during function which in turns reduces the rate of residual ridge resorption. b. Load Distribution between the Teeth and the Ridge Frechette (2001) stated that the distribution of functional stresses between the edentulous ridge and the abutment teeth represents a great challenge to any prosthodontist when treating a patient having a free end saddle. To enhance support in such a case, supporting elements must be distributed, as widely as possible, between the teeth and the residual ridge aiming to decrease the stresses on the abutment teeth. (1). Stress-Breaking The Academy of Prosthodontics (2005) defines the stress-breaker (stressdirector) as, a device or system that relieves specific dental structures of part or all of the occlusal forces and redirects those forces to other bearing structures or regions. 8

18 Review of Literature Stress breaking action may be obtained either through rigid or non rigid connection between the denture base and the direct retainer. One way of accomplishing this is by combining a rigid connection with a flexible clasp. The flexible clasp, such as the wrought wire clasp or the gingivally approaching clasp, was found to resemble a stress-breaking device since its flexibility reduces the horizontal forces on the abutment teeth. There are also some precision attachments, such as the Dalbo and the Crismani attachments that offer non rigid connection between the base and the direct retainer, which permits nearly total relief of stresses on the abutment teeth. The use of a movable joint between the denture base and the retainer was also advocated. These devices vary in their range of movement depending on the complexity of their design. Another method is incorporating a split major connector between the denture base and the direct retainer. This design allows movement of the base independent of the rigid tooth support, thereby reducing stresses on the abutment teeth (Johnson and Stratton, 1980, Preiskel, 1984, Reitz and Caputo, 1985 and Car and Brown 2011). It was revealed that the absence of stress breaking action in using non resilient attachment could result in failure, but with the use of resilient attachments, both function and esthetics can be achieved with better stress distribution on the abutment teeth (Owel, 1995 and Ku et al., 2000). (2). Impression Technique Several studies evaluated distal extension base removable partial dentures made with different impression techniques. It was demonstrated that denture base movement is directly related to the impression technique. Therefore, it is 9

19 Review of Literature advisable to record the functional rather than the resting form of the distal extension area in order to distribute the load between the teeth and the edentulous ridge. It was found that the altered-cast impression technique was the best regarding load distribution between the supporting structures. Other techniques, such as the sectional impression technique and the single selective pressure technique were also described (Holmes, 2001 and Carr and Brown, 2011). (3). Mesial Placement of the Occlusal Rest Ogata et al. (1993) clarified that rotation of the distal extension base around the fulcrum line induces heavy stresses on the anterior abutment teeth leading to its looseness. The idea that the occlusal rest of the distal extension base removable partial denture should be located on the mesial side of the abutment tooth rather than on the distal side is strongly supported. The rationale behind this idea is that the force delivered to the mesial aspect of the abutment tooth will tend to tip that tooth forward, maintaining a tight contact with the tooth immediately anterior to it and gaining stabilization and support from the remaining anterior teeth. In addition, as the rest is moved more anteriorly, the arc of rotation at any given point on the base becomes flatter and its direction becomes more perpendicular to the ridge, thereby increasing the area of the ridge that provides support to the denture (Frechette, 2001 and Mizuutchi et al., 2002). 10

20 Review of Literature c. Wide Distribution of Load over the Edentulous Ridge: A denture base should cover as much of the residual ridge as possible and be extended to the maximum within the physiologic tolerance of the limiting border structures or tissues. The broader the coverage of the edentulous area is, the greater the distribution of load and the less the load per unit area (Carr and Brown, 2011). d. Load Distribution between the Teeth: Splinting of the abutment teeth: Splinting is defined as the joining of two or more teeth into a rigid unit by means of fixed or removable restorations to provide support or bracing (The Academy of Prosthodontics, 2005). Splinting with a fixed restoration is recommended in removable partial dentures retained by precision attachments, especially in distal extension base cases. It was found that splinting of at least two abutment teeth was mandatory, as it results in a significant reduction in the stresses transmitted to them and a marked decrease in their mobility (El Charkawi and El Wakkad, 1996). Increasing the number of splinted abutment teeth to more than two does not result in reduction of the stresses transmitted to their periodontium. However, in cases with abutment teeth having weak periodontal support, it may be necessary to include more teeth within the splint (El Charkawi and EL Wakkad, 1996, Wang et al., 1998 and Itioh et al., 1998). 11