Clinical performance of full rehabilitations with direct composite in severe tooth wear patients: 3.5 Years results

Abstract

Objectives

To evaluate the mid-term clinical performance of direct composite restorations placed in patients with pathological tooth wear needing full rehabilitation with an increase of vertical dimension of occlusion.

Methods

In a prospective trial 34 patients (34.0 ± 8.4 years; 25 males, 9 females) were treated with a minimal invasive additive technique using composite restorations. The restorative treatment protocol was to provide all teeth with composite build-up restorations in an increased vertical dimension of occlusion (VDO) using the DSO-technique. Recall appointments were planned after 1 month, 1 and 3 years after treatment. Restorations were scored for clinically acceptability (FDI-criteria) and scores 4 and 5 were recorded as clinically unacceptable. Frequencies of failures and Kaplan Meier survival curves are presented and effect of relevant variables was calculated with a multifactorial Cox regression (p < 0.05).

Results

1256 Restorations were placed, 687 anterior, 324 premolar, and 245 molar restorations. After a mean observation time of 39.7 months a total of 69 failures were observed, of which 61 restorations were repaired (score 4) and 8 were replaced (score 5). Most common reasons for failure were (chip) fractures (n = 43) and caries (n = 11). Placement of anterior restorations in two sessions led to significant 4.6 times more failures then placed in one session.

Conclusions

In patients with severe tooth wear a full rehabilitation, in an increased vertical dimension of occlusion, direct composite resin restorations show a 94.8% success and 99.3% survival rate after a period of 3.5 years.

Introduction

As prevalence of caries is decreasing, especially among younger generations, more people tend to keep their dentitions relatively unrestored for life. However, surfaces of teeth abrade during function or due to acids in food and treatment of tooth wear in those individuals may pose a new challenge to the dental profession [ ]; it seems to become increasingly common, among younger adults [ ]. A pooled 30% prevalence of any sign of tooth wear of permanent teeth in children and young adults is reported, although the included studies showed wide variation [ ]. In individual cases, tooth wear may become severe and/or pathological. Severe tooth wear is defined as ‘tooth wear with substantial loss of tooth structure, with dentin exposure and significant loss (≥1/3) of the clinical crown’ while pathological tooth wear is defined as ‘tooth wear which is atypical to the age of the patient, causing pain or discomfort, functional problems, or deteriorations in aesthetic appearance, which, if progressing, may give rise to undesirable complications of increasing complexity’ [ ]. From a meta-analysis some years ago it appeared that the prevalence of severe tooth wear increased during life, from 3% with 20 year olds to 17% with 70 year olds [ ].

Due to its multifactorial nature, the aetiology of tooth wear is hard to discern [ ]. The two main causes are chemical wear and mechanical wear. Chemical wear or erosion is the loss of tooth substance by acid dissolution of either intrinsic or extrinsic origin, e.g. gastric acid or dietary acids. Mechanical wear can be divided in attrition, which is the loss of tooth substance as a result of tooth to tooth contact during normal or parafunctional masticatory activity, and abrasion, which is the wear of tooth substance through bio-mechanical frictional processes, e.g. tooth brushing [ ].

Patients with pathological tooth wear, either by chemical or mechanical cause, may need restorative care to compensate for the loss of tooth tissue, possibly comprising full rehabilitation at an increased vertical dimension of occlusion (VDO) [ ]. The conventional therapy with full crowns is challenging in terms of technical skills, financial resources and time. For this reason minimally invasive techniques are preferred, but this approach tends to be as complex and demanding as conventional techniques. Several techniques using direct or indirect composite restorations, ceramics or hybrid materials have been described to build-up worn teeth and to reconstruct the occlusion [ ]. If a worn dentition is restored, than the specific aetiology leading to the pathological condition may be a risk factor for the restorations. Ongoing erosive wear may disintegrate the marginal interface of restorations leading to breakdown. Bruxing patients impose high loads to the restoration increasing the risk for fracture [ ]. Therefore, restorations in tooth wear patients require strong materials and should be applied in a reasonable thickness to provide resistance against the forces applied during parafunctional habits [ ]. From the referred restoration techniques, long term results are only available for direct composites and different success rates have been reported [ ]. So, there is a strong need for clinical evidence for techniques and materials if a full rehabilitation in increased VDO is necessary in case of pathological tooth wear. The present report evaluates the mid-term clinical performance of direct composite resin restorations placed in patients with pathological tooth wear needing full rehabilitation with an increase of vertical dimension of occlusion. Specific risk factors on restoration and patient level were distinguished.

Materials and methods

Design and inclusion

This study was designed as a prospective trial in which patients suffering from moderate to severe tooth wear were treated (Tooth Wear Index (TWI)) ≥2; including dentine exposure in premolar and molar regions [ ]. It was aimed to provide full mouth reconstructions of the natural teeth with a minimal invasive additive technique using composite restorations, without extensive prosthetic devices. Thirty-four patients (mean age 34.0 ± 8.4 years; 25 males and 9 females) fulfilling the criteria (see below) were after written informed consent included and were randomly assigned to 1 out of 5 operators. The operators were dentists working in the academic clinic, specifically experienced in adhesive dentistry with knowledge of the applied dental procedures. Ethical approval from the METC was obtained (ABR code: NL30346.091.10).

The patients were referred by general dental practitioners to the Radboud Tooth Wear Project at the Department of Dentistry of the Radboud university medical center, Nijmegen (The Netherlands). All patients had a clear request for restorative intervention due to functional problems such as difficulties with chewing, discomfort or aesthetics. The inclusion took place between December 2010 and June 2013, using the following criteria:

  • 1)

    Patient age at least 18 years;

  • 2)

    Generalized moderate to severe tooth wear (TWI ≥ 2)with treatment demand;

  • 3)

    Full dental arches, but one diastema due to one missing tooth in the posterior area allowed.

Exclusion criteria were:

  • 1)

    Limited mouth opening (<3.5 cm);

  • 2)

    Temporomandibular dysfunction, periodontitis, deep carious lesions or endodontic problems;

  • 3)

    Systemic or local conditions that would contra-indicate dental procedures.

No exclusions were made on basis of aetiological tooth wear factors (e.g. severe bruxism of reflux). All participants signed an informed consent document before entering the study.

Baseline registrations

Baseline dental condition of each participant was documented by full-arch stone casts mounted in an articulator (Artex) in Maximal Occlusion (MO), bite-wing radiographs and intra-oral photographs. The amount of tooth wear per tooth was scored with the TWI [ ], scoring between 0 (no loss of enamel surface characteristics) and 4 (complete enamel loss, pulp exposure or secondary dentin exposure).

The assumed aetiology of the tooth wear for each patient was assessed from the casts in combination with the intra-oral photographs, using the classification system of tooth wear [ ] to broadly distinguish between erosive and mechanical wear. If for chemical wear at least 4 out of 7 characteristics and for mechanical wear at least 2 out of 4 characteristics were positively scored, the etiological factor was regarded a risk-factor. Patients with systemic underlying disease such as bulimia or gastroesophageal reflux disease were referred for adequate medical treatment. When appropriate, in cases with extrinsic erosive background, such as acidic nutrition at high frequency levels, a dietary advice was provided.

Restorative treatment

The restorative treatment protocol was to provide all teeth with composite build-up restorations followed the DSO-technique (‘Direct Shaping by Occlusion’) [ ]. First, the new vertical dimension of occlusion (VDO) was determined using the mounted casts by an operator not involved in the treatment. The required increase in VDO was based on the anticipated reconstruction of the anatomical form of the teeth, carefully considering the necessary interocclusal space posteriorly and anteriorly. To be able to convert this desired VDO to the intra-oral situation, two polyvinyl silicone bite stops (Star VPS, Danville Materials, USA) were made at both sides in the premolar area on the mounted casts in increased VDO. The stops were adjusted by removing the imprint at the occlusal side of the stop with a scalpel to allow free lateral and protrusive movements when inserted, and were intra-orally relined in Centric Relation under guided closure using the same bite registration material. The bite stops were later used as supports while reconstructing the teeth in increased VDO. Reconstructions of the teeth were generally made in CR, but in case of end-to-end anterior relation MO was preferable.

Then, according to the lip-generated smile design [ ], an intra-oral mock-up was designed using direct composite placed on teeth #13–#23 to check the new aesthetics with the patient. After approval of form and colour by the patient, the mock-up was recorded photographically for documentation and was removed. Before restoring the teeth in the new VDO, amalgam restorations were replaced with composite restorations and unreliable composite restorations were fully or partially replaced using materials and techniques as described below.

The scheme for restoring teeth in increased VDO started with the lower anterior teeth followed by the upper anterior teeth, using the bite stops as occlusal supports in the premolar region. The lingual, the incisal as well as the buccal surfaces of the anterior teeth were built up; the lower anteriors by estimated sculpting the proper anatomical form, leaving interincisal space for the upper anterior teeth. The lower anteriors were then reconstructed on the basis of the mock-up for the buccal/incisal form and available interdental space, followed by the palatal surfaces of the upper anteriors according to the DSO technique to obtain occlusion in the anterior area [ ]. The composite used on the palatal surfaces of the anteriors was Clearfil AP-X (Kuraray, Japan), on the buccal and incisal surfaces IPS Empress Direct in dentin, enamel and incisal shades (Ivoclar Vivadent, Liechtenstein).

The next step in the restoration scheme was to restore the first premolars in the upper jaw by estimated sculpting the proper anatomical form, leaving sufficient interocclusal space for the antagonist. The composites used were the same as in the anterior region, but the less esthetical demanding, the less IPS Empress Direct was used. Thereafter the first lower premolars were reconstructed by the DSO technique. The remaining premolars and the molars were built up accordingly, by occluding pairs, but for practical reasons each lower tooth was restored previous to the antagonistic upper tooth. After all teeth were reconstructed the composite restorations were finished and polished. Dependant on the operator, patient and other circumstances, between three and five treatment sessions (lasting 3 h each) were needed to accomplish the rehabilitation, with an interval of one or two weeks in between sessions. After treatment no acrylic night guards to protect the restorations were advised. Only if restorations showed clear signs of wear or fractures related to bruxism during follow-up, and interventions were needed, a night guard was provided.

All materials were used as prescribed by the manufacturers. For adhesion, a three step etch-and-rinse system was used, including 37% phosphoric acid (DMG, Germany), Clearfil SA Primer and Clearfil Photobond (Kuraray, Japan). Light curing unit was the Bluephase 16i (Ivoclar Vivadent, Liechtenstein; maximum output 1.600 mW/cm 2 ). For gingival contouring, metal (Tofflemire nr.11, KerrHawe, Switzerland) and plastic matrices (Directa, Sweden) were used, secured by wooden interdental wedges. Before applying the composite, in case of using the DSO technique, the occlusal part of the matrix that intervened with the antagonist under occlusion, was removed. To improve the adaptation at the outline, in several cases a thin layer of flowable composite (Clearfil Majesty Flow (Kuraray, Japan)) was injected and left uncured before the composite was applied using the snow-plough technique [ ] In case the buccal veneering of the anteriors was performed in a separate session than the palatal composite restorations, the adhesive surface of the latter was sandblasted (CoJet (3 M ESPE,USA) and Danville MicroEtcher CD (Danville Materials, USA)) and a silane coupling agent (Clearfil Porcelain Activator (Kuraray, Japan)) was applied. This procedure was also used to pre-condition teeth with existing composite restorations underneath the build-up restorations.

Clinical evaluation and interventions

Recall appointments were planned after 1 month, 1 and 3 years after treatment. During each recall a set of intra-oral photographs as well as full arch impressions (Virtual Light Body Fast Set/Virtual 380 Heavy Body Fast Set Tray Material (Ivoclar Vivadent, Liechtenstein)) were made, including a bite registration made of Flexitime Bite (Heraeus Kulzer, Germany). Die stone casts were made and mounted in an articulator. The actual increase of VDO was measured on those casts, being the difference in height at the deepest point of the sulcus buccally of the first upper and lower molar at baseline and 1 month recall. Both right and left side were measured to obtain a mean value.

Two observers (BL and BS) performed the recall registrations, including assessment of the restorations for clinically acceptability. FDI-criteria were used, focussing on the functional, biological and esthetical properties, in which scores 4 and 5 were recorded as clinically unacceptable [ ]. Restorations with score 4 were repaired and restorations with score 5 were replaced Besides, all participants were under regular maintenance checks with their ‘own’ general dentist (GD) and he or she was contacted whether any intervention related to the composite reconstructions was carried out. The type of intervention (like fracture, caries, discoloration and roughness) and the repair procedure were recorded (polishing, repair or replacement of the restoration). Interventions such as polishing of anterior buccal veneer restorations due to external staining or the removal of a local roughness of a restoration were regarded as regular maintenance (score 2 of the FDI criteria). These interventions were not considered ‘failure’.

Statistical analysis

Frequencies of failures and Kaplan Meier survival curves are presented. Annual failure rates (AFR) were calculated together with success and survival rates [ ]. Success is the restoration that survives the full observation period without intervention. Survival is the restoration that had to be repaired to be able to survive the full observation period; end-point of success for this restoration is the date the repair was performed. A buccal veneer restoration, being made of a different material, was counted as a separate restoration irrespective of the date of placement. In some cases the buccal veneer was placed in different session, which was a variable in the analysis. In accordance, the statistical unit in the analysis is the ‘restoration’ and not the ‘tooth’.

For the restoration that has been replaced both end-points (success and survival) were the date of re-restoration. The effect of relevant independent variables to restoration survival (age, assumed type of tooth wear, jaw, tooth type, and placement the buccal and palatal/lingual restoration in separate sessions) were analysed with multifactorial Cox regression models. To adjust for dependency if more than one restoration failed in one patient, Cox models use a cluster term to adjust variance estimates for the clustering of restorations within patients. Survival analyses were done using the library survival (v 2.39) within the R software [ ] (v 3.3.2) and the p-value was set at 0.05.

Materials and methods

Design and inclusion

This study was designed as a prospective trial in which patients suffering from moderate to severe tooth wear were treated (Tooth Wear Index (TWI)) ≥2; including dentine exposure in premolar and molar regions [ ]. It was aimed to provide full mouth reconstructions of the natural teeth with a minimal invasive additive technique using composite restorations, without extensive prosthetic devices. Thirty-four patients (mean age 34.0 ± 8.4 years; 25 males and 9 females) fulfilling the criteria (see below) were after written informed consent included and were randomly assigned to 1 out of 5 operators. The operators were dentists working in the academic clinic, specifically experienced in adhesive dentistry with knowledge of the applied dental procedures. Ethical approval from the METC was obtained (ABR code: NL30346.091.10).

The patients were referred by general dental practitioners to the Radboud Tooth Wear Project at the Department of Dentistry of the Radboud university medical center, Nijmegen (The Netherlands). All patients had a clear request for restorative intervention due to functional problems such as difficulties with chewing, discomfort or aesthetics. The inclusion took place between December 2010 and June 2013, using the following criteria:

  • 1)

    Patient age at least 18 years;

  • 2)

    Generalized moderate to severe tooth wear (TWI ≥ 2)with treatment demand;

  • 3)

    Full dental arches, but one diastema due to one missing tooth in the posterior area allowed.

Exclusion criteria were:

  • 1)

    Limited mouth opening (<3.5 cm);

  • 2)

    Temporomandibular dysfunction, periodontitis, deep carious lesions or endodontic problems;

  • 3)

    Systemic or local conditions that would contra-indicate dental procedures.

No exclusions were made on basis of aetiological tooth wear factors (e.g. severe bruxism of reflux). All participants signed an informed consent document before entering the study.

Baseline registrations

Baseline dental condition of each participant was documented by full-arch stone casts mounted in an articulator (Artex) in Maximal Occlusion (MO), bite-wing radiographs and intra-oral photographs. The amount of tooth wear per tooth was scored with the TWI [ ], scoring between 0 (no loss of enamel surface characteristics) and 4 (complete enamel loss, pulp exposure or secondary dentin exposure).

The assumed aetiology of the tooth wear for each patient was assessed from the casts in combination with the intra-oral photographs, using the classification system of tooth wear [ ] to broadly distinguish between erosive and mechanical wear. If for chemical wear at least 4 out of 7 characteristics and for mechanical wear at least 2 out of 4 characteristics were positively scored, the etiological factor was regarded a risk-factor. Patients with systemic underlying disease such as bulimia or gastroesophageal reflux disease were referred for adequate medical treatment. When appropriate, in cases with extrinsic erosive background, such as acidic nutrition at high frequency levels, a dietary advice was provided.

Restorative treatment

The restorative treatment protocol was to provide all teeth with composite build-up restorations followed the DSO-technique (‘Direct Shaping by Occlusion’) [ ]. First, the new vertical dimension of occlusion (VDO) was determined using the mounted casts by an operator not involved in the treatment. The required increase in VDO was based on the anticipated reconstruction of the anatomical form of the teeth, carefully considering the necessary interocclusal space posteriorly and anteriorly. To be able to convert this desired VDO to the intra-oral situation, two polyvinyl silicone bite stops (Star VPS, Danville Materials, USA) were made at both sides in the premolar area on the mounted casts in increased VDO. The stops were adjusted by removing the imprint at the occlusal side of the stop with a scalpel to allow free lateral and protrusive movements when inserted, and were intra-orally relined in Centric Relation under guided closure using the same bite registration material. The bite stops were later used as supports while reconstructing the teeth in increased VDO. Reconstructions of the teeth were generally made in CR, but in case of end-to-end anterior relation MO was preferable.

Then, according to the lip-generated smile design [ ], an intra-oral mock-up was designed using direct composite placed on teeth #13–#23 to check the new aesthetics with the patient. After approval of form and colour by the patient, the mock-up was recorded photographically for documentation and was removed. Before restoring the teeth in the new VDO, amalgam restorations were replaced with composite restorations and unreliable composite restorations were fully or partially replaced using materials and techniques as described below.

The scheme for restoring teeth in increased VDO started with the lower anterior teeth followed by the upper anterior teeth, using the bite stops as occlusal supports in the premolar region. The lingual, the incisal as well as the buccal surfaces of the anterior teeth were built up; the lower anteriors by estimated sculpting the proper anatomical form, leaving interincisal space for the upper anterior teeth. The lower anteriors were then reconstructed on the basis of the mock-up for the buccal/incisal form and available interdental space, followed by the palatal surfaces of the upper anteriors according to the DSO technique to obtain occlusion in the anterior area [ ]. The composite used on the palatal surfaces of the anteriors was Clearfil AP-X (Kuraray, Japan), on the buccal and incisal surfaces IPS Empress Direct in dentin, enamel and incisal shades (Ivoclar Vivadent, Liechtenstein).

The next step in the restoration scheme was to restore the first premolars in the upper jaw by estimated sculpting the proper anatomical form, leaving sufficient interocclusal space for the antagonist. The composites used were the same as in the anterior region, but the less esthetical demanding, the less IPS Empress Direct was used. Thereafter the first lower premolars were reconstructed by the DSO technique. The remaining premolars and the molars were built up accordingly, by occluding pairs, but for practical reasons each lower tooth was restored previous to the antagonistic upper tooth. After all teeth were reconstructed the composite restorations were finished and polished. Dependant on the operator, patient and other circumstances, between three and five treatment sessions (lasting 3 h each) were needed to accomplish the rehabilitation, with an interval of one or two weeks in between sessions. After treatment no acrylic night guards to protect the restorations were advised. Only if restorations showed clear signs of wear or fractures related to bruxism during follow-up, and interventions were needed, a night guard was provided.

All materials were used as prescribed by the manufacturers. For adhesion, a three step etch-and-rinse system was used, including 37% phosphoric acid (DMG, Germany), Clearfil SA Primer and Clearfil Photobond (Kuraray, Japan). Light curing unit was the Bluephase 16i (Ivoclar Vivadent, Liechtenstein; maximum output 1.600 mW/cm 2 ). For gingival contouring, metal (Tofflemire nr.11, KerrHawe, Switzerland) and plastic matrices (Directa, Sweden) were used, secured by wooden interdental wedges. Before applying the composite, in case of using the DSO technique, the occlusal part of the matrix that intervened with the antagonist under occlusion, was removed. To improve the adaptation at the outline, in several cases a thin layer of flowable composite (Clearfil Majesty Flow (Kuraray, Japan)) was injected and left uncured before the composite was applied using the snow-plough technique [ ] In case the buccal veneering of the anteriors was performed in a separate session than the palatal composite restorations, the adhesive surface of the latter was sandblasted (CoJet (3 M ESPE,USA) and Danville MicroEtcher CD (Danville Materials, USA)) and a silane coupling agent (Clearfil Porcelain Activator (Kuraray, Japan)) was applied. This procedure was also used to pre-condition teeth with existing composite restorations underneath the build-up restorations.

Clinical evaluation and interventions

Recall appointments were planned after 1 month, 1 and 3 years after treatment. During each recall a set of intra-oral photographs as well as full arch impressions (Virtual Light Body Fast Set/Virtual 380 Heavy Body Fast Set Tray Material (Ivoclar Vivadent, Liechtenstein)) were made, including a bite registration made of Flexitime Bite (Heraeus Kulzer, Germany). Die stone casts were made and mounted in an articulator. The actual increase of VDO was measured on those casts, being the difference in height at the deepest point of the sulcus buccally of the first upper and lower molar at baseline and 1 month recall. Both right and left side were measured to obtain a mean value.

Two observers (BL and BS) performed the recall registrations, including assessment of the restorations for clinically acceptability. FDI-criteria were used, focussing on the functional, biological and esthetical properties, in which scores 4 and 5 were recorded as clinically unacceptable [ ]. Restorations with score 4 were repaired and restorations with score 5 were replaced Besides, all participants were under regular maintenance checks with their ‘own’ general dentist (GD) and he or she was contacted whether any intervention related to the composite reconstructions was carried out. The type of intervention (like fracture, caries, discoloration and roughness) and the repair procedure were recorded (polishing, repair or replacement of the restoration). Interventions such as polishing of anterior buccal veneer restorations due to external staining or the removal of a local roughness of a restoration were regarded as regular maintenance (score 2 of the FDI criteria). These interventions were not considered ‘failure’.

Statistical analysis

Frequencies of failures and Kaplan Meier survival curves are presented. Annual failure rates (AFR) were calculated together with success and survival rates [ ]. Success is the restoration that survives the full observation period without intervention. Survival is the restoration that had to be repaired to be able to survive the full observation period; end-point of success for this restoration is the date the repair was performed. A buccal veneer restoration, being made of a different material, was counted as a separate restoration irrespective of the date of placement. In some cases the buccal veneer was placed in different session, which was a variable in the analysis. In accordance, the statistical unit in the analysis is the ‘restoration’ and not the ‘tooth’.

For the restoration that has been replaced both end-points (success and survival) were the date of re-restoration. The effect of relevant independent variables to restoration survival (age, assumed type of tooth wear, jaw, tooth type, and placement the buccal and palatal/lingual restoration in separate sessions) were analysed with multifactorial Cox regression models. To adjust for dependency if more than one restoration failed in one patient, Cox models use a cluster term to adjust variance estimates for the clustering of restorations within patients. Survival analyses were done using the library survival (v 2.39) within the R software [ ] (v 3.3.2) and the p-value was set at 0.05.

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Jun 17, 2018 | Posted by in General Dentistry | Comments Off on Clinical performance of full rehabilitations with direct composite in severe tooth wear patients: 3.5 Years results
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