A Comparison of Composite Post Buildups and Cast Post-and-Core Buildups for the Restoration of Nonvital Teeth After 5 to 10 Years

Ronald E. Jung, Dr Med Denta/Oren Kalkstein, Dr Med Dentb/lrena Sailer, Dr Med Dente/ Malgorzata Roos, PhDd/Christoph H. F. Hammerle, Prof Dr Med Dente

Purpose: The aim of this study was to compare the cumulative survival rates and the complication rates of established methods of indirect cast posts and cores and direct posts and composite cores over at least 5 years within a retrospective study of patients who received fixed restorations. Materials and Methods: The patients were questioned according to a protocol and were examined clinically and radiologically. Of the 101 patients who were recruited, 72 came for a followcup examination. Results: Forty-one cast posts and cores and 31 composite cores were examined clinically and radiologically after an average observation period of 8.56 (SO 1.45) years. Four teeth were extracted during the observation period, and 2 more were extracted at the time of the examination. This resulted in cumulative survival rates of 90.2% for cast posts and c~res and 93.5% for composite cores. There were 28 complications altogether, consisting of 2 (7.1 %) root fractures, 8 (28.6%) teeth with increased probing depths, 3 (10.7%) with increased degrees of mobility, 4 (14.3%) with caries, 9 (32.1 %) with periapical radiolucency and/or retrograde filling, and 2 (7.1 %) with loss of retention. No statistically significant differences between the 2 methods could be found regarding survival and complication rates. Conclusion: It can be concluded that over an average observation period of 8.56 years the indirect cast post-and-core buildup and the direct composite post buildup can be considered of similar value. Int J Prosthodont 2007;20:63-69. ""'

n essential task of dentistry is the restoration of vital teeth, the restoration of this substance is as im- A tooth substance. Different procedures are adopted portant as the anchoring of the restoration material. In for the treatment of vital and nonvital teeth. Because such cases, root posts are used in the clinic to reinforce of the usually greater loss of tooth substance in non- the buildup materials. These posts have been made of wood, steel, gold, , zirconia, and glass fiber. Recommendations for the ideal post material can be found in the literature. It should have physical char- aAssistant Professor, Department of Fixed and Removable acteristics similar to those of dentin,' it should be bio- and Dental Material Science, University of Zurich, compatible, and it should be able to adhere well to the Switzerland. 2 bprivate Practice, Affoitern a. A. Zurich, Switzerland. tooth substance. CAssistant Professor, Department of Fixed and Removable Although formerly it was thought that a post Prosthodontics and Dental Material Science, University of Zurich, strengthened nonvital teeth,3,4 new studies have shown Switzerland. that posts in fact weaken nonvital teeth.s-9 In spite of dPhD, Bi~statistic,ISPM, University of Zurich, Switzerland. this weakening, the use of a post to anchor the buildup ·Professor and Chairman, Department of Fixed and Removable Prosthodof}tics and Dental Material Science, University of Zurich, of a severely damaged nonvital tooth is usually indis- Switzerland. pensable. In cases of rather damaged nonvital and root-filled anterior and posterior teeth requiring a fixed Correspondence 'to: Dr Ronald E. Jung, Clinic for Fixed and Removable Prosthodontics and Dental Material Science, , post buildups are almost always necessary School, University of Zurich, Plattenstrasse 11, CH-B032 Zurich, because of the poor mechanical resistance of the re- Swit7erfand. fax: +41-1-634-43-05. E-mail.'jl [email protected] maining tooth structure.1O '~ , ~- - '.' ~ • L _. ~ , •• ~ ~ _ _ _ ~:.._~:~~--...~-,;~-:,...--...,'.:...:...... ::.-,.;:'.~::";:::-~~- :;;.....:--<'";.::- •• ~-""""'"."' •.• _ •.~.~ •.••• -.-"-- ~:. '-.~:-.-..-:... -",,.. ~..::::'''':-:_-~.~ -_--.:...•.. "'~•.•.••. ~~, - .: •• ~- .'-

Frequently used materials for core buildups are age" , gold, glass-ionomer cement, composite, and (mec ceramic.11•12 The materials differ not only in their phys- All patients were examined clinically and radiologi- who ical characteristics, biocompatibility, and esthetic qual- cally and questioned according to the protocol. The pa- relati ities but also in the time and effort necessary for their tients were asked whether they regularly (at least once their application and in their treatment costs. The cast post- a year) went to a dentist ora dental hygienist for a re- tient~ and-core buildup and the composite post buildup are call visit. Also, the patients were asked about their eithe the most widely used because of their good biocom- smoking behavior. Those patients who had lost the Th patibility and appealing physical characteristics. tooth that had been chosen for examination during the shoY'. The aim of this study was to compare the cumula- period of observation and were no longer being treated 1.45) tive survival rates (CSRs)and the complication rates of at the University of Zurich were asked for the names regul the established methods of indirect cast post-and- of their private dentists. This enabled the authors to Of core buildup and direct composite post buildup over at document the time at which the tooth was lost. to be least 5 years in function by means of a retrospective The randomly selected teeth were examined clini- tient study of patients who received a fixed restoration with cally and radiologically. Clinically, probing depth, bleed- from post buildups. ing on probing, tooth mobility, the width of keratinized all WI gingiva, and recession were measured. Furthermore, noset the marginal adaptation was assessedaccording to the ing tt modified United States Public Health Service criteria. how€ The teeth examined were radiographed using the par- tient. allel technique (Hawe x-ray film holder, Kerrhawe). One hundred one patients who had received a cast These radiographs were evaluated by 2 independent post-and-core buildup or a composite post buildup at examiners, who focused on the following abnormalities the Clinic for Fixedand RemovableProsthodontics at the and diagnoses: root fractures, periapical signs of University of Zurich between September 1991and May pathology, retrograde root fillings, periodontitis, and 1997 were recruited for a follow-up examination caries. In addition, these radiographs w~Fe used to between January and May 2004.If patients had received measure,to the nearest half millimeter, the~ost length, several post buildups, the tooth that was to be examined the length, and the length of any residual root was chosen randomly early in the preclinical work. canal filling.

All post buildups were made by saving as much tooth Means, standard deviations, and medians were calcu- substance as possible. Forall post buildups, tapered or lated for all data. For statistical analysis,the chi-square cylindric-tapered CM (Cendres & Metaux) and Mooser test was used to show the dependency of 2 discrete cri- posts (Cendres & Metaux) sizes 1 to 4 were used. For teria. When both criteria only had 2 categories, the the composite buildups, titanium posts were used, and exact Fisher test was used. A survival analysis was for the cast post-and-core buildups, gold posts were performed and the data were shown graphically as used. The composite buildups were fabricated with ei- Kaplan-Meier curves. The CSR is the estimate of the ther Core-Paste (Coltene) together with the All-Bond proportion of individuals that have not experienced adhesive system (Bisco) or with Tetric (Ivoclar) to- the event (tooth loss) from time 0 (insertion of the re- gether with the Syntac adhesive system (Ivoclar). construction) to the time of interest t (clinical exami- The indirect cast post-and-core buildups were made nation). The differences between the survival curves in 2 steps. As a first step, polymethylmethacrylate were evaluated with log-rank tests. (PMMA) (Duralay, Reliance Dental) was built up The results of statistical tests with Pvalues under 5% around the gold post directly in the patient's mouth. were judged as significant. The statistical analysis was This buildup was then sent to the dental laboratory, carried out using Stat View version 5 (SAS Institute). where in a second step the PMMA was replaced by Protor 3 (Cendres & Metaux), a gold-platinum alloy containing mostly gold. The replacement was done using the standard casting technique. Before insertion all posts were sandblasted with 50- Of the 101 recruited patients, 72 could be examined mm AI203 at 4 bar and thereafter cemented either with zinc phosphate (Dentsply De Trey), glass ionomer clinically and radiologically. Seventeen (23.6%) of them (Ketac Cem, ESPE),or composite (Panavia, Kuraray). were men and 55 (76.4%) were women. Their average age was 54 years at the time of cementing the buildups for the cast post-and-core buildups. The cast post-and- (median 62.15years; range, 31 to 73). Of those patients core buildups had an average post length of 8.2 mm, who did not show up for the examination, there were which was approximately 1 mm longer than the 7.0 mm relatively more men (43.3%) than women (22.5%) and of the composite post buildups. The ratio of post length their average age was 61.35years (SO 13.06);these pa- to crown length was very similar in both bUildup types: tients had either died or could not be found because 0.92 (SO 0.28) for cast post-and-core buildups and either their home address or their name had changed. 0.86 (SO 0.30) for composite post buildups. The average observation period of the patients who showed up for the examination was 8.56 years (SO 1.45). Forty-nine (68.1%) patients said they attended regular recall·visits. Tooth loss. In 4 of the 72 patients, the tooth chosen Of the 72 patients, 11 (15.3%) declared themselves to be examined was no longer in situ. In 2 other pa- to be smokers. No radiograph was obtained for one pa- tients, the teeth were so massivelydestroyed at the time tient because she was pregnant. Five patients suffered of examination that they could no longer be restored from diabetes at the time of the examination; however, and so were registered as lost teeth. Altogether, there- all were receiving treatment. Four patients were diag- fore, 6 (8.3%) teeth were lost (Table 2). nosed with a carcinoma in the time between cement- The different types of tooth Oncisor,canine, premo- ing the post and the date of the follow-up examination; lar, molar) were combined forthe statistical evaluation however, none were situated in the jaw region. One pa- of the maxilla and the mandible. No significant differ- tient suffered from Sjogren syndrome. ences were observed between these 4 groups with re- gard to the distribution of tooth loss (chi-square, P= .2567). In addition, no statistically significant difference was Out of the 72 teeth examined, 46 (63.90Al) were in the detected in tooth losses between the 2 buildup types, maxilla and 26 (36.1%) were in the mandible. either for the 4 teeth that had been provided with a cast Altogether, 41 (56.9%) cast post-and-core buildups and 31 (43.1%) composite post buildups were exam- ined. The distribution of the buildup types showed sig- Table 1 Characteristics of the 72 Teeth Eyaluated in the nificantly more cast post-and-core buildups in the re- Study gion of the inqisors and the canines, whereas in the molar region fflere were significantly more composite Cast gold post-and- Composite post Characteristic core buildups buildups post buildups (chi-square, P= .0006) (Table 1).A sim- ilar distribution regarding buildup materials and tooth Total no. of buildups 41 31 position was observed for the patients who did attend Location Incisors 9 2 the examination. Canines 10 1 The buildups were inserted with 3 different types of Premolars 21 19 cement (Table 1).The distribution of buildup types did Molars 1 9 Cement type not show any relationship to the type of cement used Glass ionomer 7 6 (chi-square, P= .078).The distribution of cement types Composite 22 21 also did not show any relationship to the various posi- Zinc phospt;late 9 1 Could not be evaluated 3 3 tions of the teeth (chi-square, P= .2384). Type of restoration The average length of the apical part of the Fixed partial denture 16 13 treatment of the examined teeth was 3.6 mm (SO 1.8) Single crown 20 14 Splinted crown 5 4 for the composite post buildups and 3.8 mm (SO 1.9)

Survival Type of Type of tooth time (y) Type of buildup reconstruction Reason for extraction

''premolar (maxilla) 3.13 Cast post and core Fixed partial denture Periapical pathology Incisor (maxilla) 5.42 Composite Fixed partial denture Periapical pathology Incisor (maxma) 5.53 Cast post and core Single crown Root fracture Molar (mandible) 7 Cast post and core Fixed partial denture Periapical pathology Canine (maXilla) 8 Composite Splinted crown Periapical pathology and caries Canine (maxilla) 9.62 Cast post and core Fixed partial denture Root frac1ure Fig 1 (/eft) CSRs of cast post-and-core buildups and com- posite post buildups over an average observation period of 8.56 100 years (Kaplan-Meier) 80 ~ 60 [[ (f) 40 0 20 --- Composite buildup - Cast gold buildup 0 , , . o 2 4 6 8 10 12 Time (y) Fig 2 (below) Distribution of the total number of complications according to type of complication and type of buildup

18 Ifj Gold buildup ~ 16 Composite buildup o 14 o .~S? 12 a. 10 § 8 oo 6 ci 4 z 2 o Root Probing depth Increased Caries Periapical Loss of Total fracture ? 5 mm tooth mobility radioluc/ retention complications retrogr filling

post-and-core buildup or for the 2 teeth with com- buildups. There was no statistically significant differ- posite post buildup (chi-square, P= .735). From these ence between the 2 buildup types of the teeth with data, a CSRof 90.2% was measured for the cast post- periapical radiolucency or retrograde fillings. In and-core buildups, versus a CSR of 93.5% for com- addition, no significant relationship was found in the posite post buildups over an average observation pe- incidence of periapical radiolucency/retrograde filling riod of 8.56 years (Fig 1). complications and the residual length of the apical root Complications. Probing depths of ;;"5 mm were canal sealing. measured for 8 of 72 teeth. Of these 8 teeth, 5 had been By looking through the patients' histories and by provided with cast post-and-core buildups and 3 re- questioning the patients, the authors found 2 retention ceived composite post buildups. Of the 72 teeth ex- losses of the examined restorations, and they were amined, 3 (1 cast post-and-core buildup, 2 composite evenly distributed (1 each ofthe 2 buildup types). One post buildups) showed a mobility degree of 3 or 4. tooth was extracted shortly after retention loss be- Of the 4 teeth that had been diagnosed as having cause of a root fracture, and the other was judged no caries in the clinical examination, 2 had been provided longer reconstructible. Both were finally classified as with cast post-and-core buildups and 2 had received tooth losses. composite post buildups. The teeth of patients who did Thus, 28 complications were found in the entire pa- not show up regularly for recall exhibited a higher tient sample; 16 were cast post-and-core buildups, caries incidence compared to the teeth of patients and 12were composite post buildups (Fig 2). Of all the who regularly showed up for recall. The 2 teeth with teeth examined, 11 (26.8%) of the 41 teeth with cast root fractures had been provided with cast post-and- post-and-core buildups showed at least 1 complica- core buildups and could no longer be treated. tion, as did 8 (25.8%) of the 31 teeth with a composite At the follow-up examination, 9 teeth either showed post buildup. However, a total of only 6 buildups ended periapical radiolucency and/or had been treated either in tooth or restoration loss. The individual teeth with with only an apical root resection or a simultaneous complications, listed according to the type of restora- retrograde filling since cementation of the post tion, are shown in Table 3. Table 3 Distribution of Complications According to Type of Reconstruction

Singlecrowns Fixedpartialdenture Splintedcrowns Typeof complication CastP&C Composite CastP&C Composite CastP&C Composite

Rootfracture 1 0 1 0 0 0 Pocketdepths" 5 mm 2 2 3 1 0 0 Tooth mobility 3 and 4 0 0 , , 0 1 Caries 0 , 2 0 0 1 Periapicalpathology 2 0 2 2 , 2 Lossof retention 1 , 0 0 0 0 Totalcomplications 6 4 9 4 , 4

P&C = postandcore.

2o less independently using in vitro studies. ,21 Various aspects were examined. such as post design. treatment It was shown in this retrospective study that there were of the apical part of the root canal. post material. post no statistically significant differences in CSRs and com- length. cement type. buildup material. and the ferrule plication rates between indirect cast post-and-core effect. buildups and direct composite post buildups over an av- All posts used in the present study were cylindric- erage observation period of 8.56 years. In this compar- tapered or tapered. The biomechanical characteristics ative study. the indirect cast post-and-core buildups of different post forms have been evaluated in the lit- showed a CSR of 90.2%. and the direct composite post erature. On the one hand. the onset of a wedge effect buildups showed a CSR of 93.5%. These values corre- was noted when cylindric-tapered posts were used. spond. on average. to the survival rates described in the whereas no such onset was found when parallel and dental literature for diverse post buildup materials over tapered posts were used.8.22 All post buildups used in 13 18 various observation periods. - In most studies. how- the present study were provided with a vertical stop in ever. the average observation period was shorter. which the form of a canal inlay. since it has been demon- restricts comparability to the present study. For cast strated that an inlay is able to reduce the wedge effect post-and-cory buildups. a CSR of 90.6% was found of tapered postS.23 In an in vivo study that considered over an average period of 6 years; caries. root fracture. different post systems. screws showed the lowest sur- and retention loss were responsible for the extractions vival rate and always caused massive pressure to de- or the provision of a new restoration.13 Two clinical velop in the roOt.15 studies showed survival rates of composite post Ideally. the time between root treatment and post buildups over an observation period of more than 8 setting should be as short as possible to minimize the years. There. of a total of 67 teeth that had been checked risk of endodontic failure.24,25 In addition, it was shown in a follow-up examination and had been provided with that. in teeth with a post buildup, significantly more composite post buildups, 7 extractions were performed. periapical radiolucency was found in teeth with a post corresponding to a CSR of 89.6%.16 In the second study. buildup that had an apical sealing of less than 3 mm.26 51 teeth with mainly screws and composite post The average length of the apical part of the root canal buildups were followed up over a period of 10 years. In treatment of the teeth examined in the present study that time. 6 teeth (12%) were lost because of caries. root was 3.7 mm. In spite of the demand for at least a 3-mm- fractures. and retention loss; this amounted to a survival long apical portion. the apical part of the root canal rate of 88% over 10 years.15 The slightly lower survival treatment varied between 0 and 8.5 mm. However, no rate of the composite post buildups in these 2 studies correlation between the teeth with apical radiolucen- versus the present study may possibly be explained by cies/retrograde root fillings and the length of the api- the increased use of screws. Similar complication rates cal part of the could be found. The between the post buildup types described in the study frequency of nonvital teeth with apical radiolucen- presented here agree with the findings of a review of cies/retrograde root fillings (12.5%) found in this study 10 in vitro and 6 in vivo studies.19 In these it was also corresponds to that of 12.1% found in a study of fixed shown tfiat no evidence exists for a preference of either partial with cantilevers.27 post buildup type. The buildups of both studied groups were cemented Accordin~ to the literature. the prognosis for teeth with 3 different types of cement (zinc phosphate. glass provided with post buildups is dependent on a wide ionomer. and composite); composite was used in nearly range of factors. These factors were examined more or two thirds of all buildups. Various studies· showed that adhesive fixation of posts in the root canal by means of composite cement resulted in improved retention and increased pullout forces of the coronal restora- It can be concluded that over an average observation tion.28.29This fact and the fact that no fixed partial den- period of 8.56 years the indirect cast post-and-core tures with cantilevers were used could explain the buildup and the direct composite postbuildup can be small number of retention losses found in the present considered of similar value when taking into account study.3o Because composite cements have an elastic the CSRand the frequency of root fractures, increased modulus similar to that of dentin, the fortification of a probing depths, increased tooth mobility, caries, peri- thin root wall as a result of the adhesion of the cement apical lesions, and loss of retention. However, it must is also discussed.31.32In addition, composite cements be taken into consideration that in the present study, have been shown to be superior to the zinc phosphate more cast post-and-core buildups were placed in the and glass-ionomer cements in terms of microleak- region of the incisors and the canines, whereas in the age.33A disadvantage of the composite cements, how- molar region there were more composite post buildups. ever, is seen in their high technical sensitivity.34.35Inad- dition, temporary cements that include eugenol can have a negative influence on the adhesive power of composite cements.36.37Inspite of these many factors, 1. Assif 0, Oren E.Marshak BL,Aviv I.Photoelastic analysis of stress it was found in the present study that, when the es- transfer by endodontically treated teeth to the supporting struc- ture using different restorative techniques. J Prosthet Dent sential biomechanical principles in treating nonvital 1989;61:535-543. teeth with posts were followed, the choice of cement 2. Deutsch AS. Musikant BL, Cavallari J. Lepley JB. Prefabricated did not playa significant role for the prognosis of the dowels a literature review. J Prosthet Dent 1983;49:498-503. treated tooth. 3. Kantor ME. Pines MS. A comparative study of restorative tech- The different buildup materials have also been com- niques for pulpless teeth. J Prosthet Dent 1977;38:405-412. 4. Trabert KC.Caputo M. Abou-Rass M. Tooth fracture: A compar- pared and assessed in a range of situations. Although ison of endodontic and restorative treatments. J Endod composite clearly exhibits a lower modulus of elastic- 1978;4:344-345. ity and flexure strength than gold, no statistically sig- 5. Sorensen JA. Martinoff JT. Clinically signifi