Are dentine pins obsolete?

Dentine pins have been used in operative dentistry for many years to retain a non-adhesive restorative material (such as dental amalgam) in a cavity which has little or no inherent mechanical retention. However, dentine pin placement can be a hazardous procedure and there are a number of problems associated with their use. Alternative techniques have been described which may be utilized and are effective at retaining the restorative material without the shortcomings of dentine pins. There is a strong argument therefore that dentine pins have no place in contemporary dental practice and have consequently become obsolete.

Pins for direct restorations.

Self-threading dentine pins permit the retention of large complex direct restorations but there are problems associated with their placement. Strain and crazing of dentine following pin insertion and pulpal and lateral perforations are common. Perforations can be avoided by operator awareness of tooth morphology. Strain and crazing has been found to be minimized by unscrewing the pin slightly after insertion, by using pins with a tap thread, and by using the smallest pin possible. Twist drill form and dulling affects the pin channel shape which in turn influences pin seating. A lack of standardization of pin and twist drill diameter and length has been implicated as the cause of poor pin retention. Manufacturers, in an attempt to standardize the depth of penetration of pins, have incorporated shoulders at the midpoint of the pin, which has met with varying success. More research in the area of limiting pin penetration is necessary, as well as attempts to improve the quality control of pin and twist drill manufacture.

The undiagnosed split-root syndrome.

The split-root syndrome is an often misdiagnosed painful condition. The major causes of the splits have been discussed. In addition, classical symptoms associated with this syndrome have been illustrated by two case reports to facilitate the syndrome's recognition.

The heat sink and its relationship to reducing heat during pin-reduction procedures.

When self-threading pins are used in the restoration of teeth, the heat generated by cutting these pins to the correct length may traumatize the pulp. This study evaluated cotton forceps and a mosquito hemostat used as a heat sink and at different positions on the pin to determine any change in heat transferred to the tooth. Three hundred self-threading pins (Whaledent TMS System: 100 each of the Regular, Minim, and Minikin sizes) were inserted into freshly extracted teeth and sectioned. The temperature change at the apical end of the pin was measured using a thermistor probe. The results indicated that metal supporting instruments can be effective in reducing heat transferred to the apical aspect of the pin during pin reduction.

Influence of different transitional restorations on the fracture resistance of premolar teeth.

Controversy exists over the most favorable material and type of restoration to be used to transitionally restore teeth destined to be crowned. This in vitro study uses fracture resistance testing to compare eight different transitional restorations in maxillary premolars. Ninety sound maxillary premolars were randomly selected and allocated to nine groups, each comprising 10 teeth. One group remained unrestored and was used as the control. Teeth in the remaining groups were prepared to a standard cavity form using: a copy milling process removing the palatal cusp. Restorations were placed using amalgam with dentin pins and cavity varnish; amalgam with an amalgam bonding agent; resin composite with dentin pins and a dentin bonding agent; resin composite with a dentin bonding agent only; resin-modified glass ionomer with dentin pins; resin-modified glass ionomer cement alone and cermet with dentin pins and cermet alone. Each restored tooth was then subjected to axial loading via a bar contacting the buccal and restored palatal cusps until failure of the restored tooth occurred. The mean load-to-fracture values were statistically compared and the modes of failure recorded. It was found that the choice of restorative material and type of restoration had little effect on the fracture resistance of the restored tooth with the exception of those teeth restored with reinforced glass ionomer cement alone, which exhibited a significantly lower resistance to fracture than the other restored teeth. However, the choice of restorative material/technique did influence the mode of failure. Failure in teeth restored with resin-modified glass ionomer cement alone produced the least damage to the remaining tooth tissue when failure occurred. Consequently, this material may offer the most favorable range of properties for the transitional restoration of extensively broken-down maxillary premolar teeth destined to be crowned. Furthermore, the findings of this study fail to support the use of dentin pins in the placement of bonded build-up restorations.

Retentive pins. Their use and misuse.

Retentive pins have brought with them both ecstasy and agony. Their history, use, and situations resulting from their misuse are reviewed in this article. Correction of common errors will prove useful to the reader.

Complications and prognostic considerations in operative dentistry.

Several aspects of routine operative treatment procedures may result in particularly challenging problems and complications. This article reviews the potential for such complications with emphasis on the ultimate treatment prognosis.

Strength of amalgam restorations bonded with Amalgambond.

The objective of this study was to determine the strength of bonded amalgam restorations involving an entire cusp. Four groups were established, each containing 13 caries-free, recently extracted molar teeth of similar size and anatomic form. The teeth were stored in 70% alcohol prior to the removal of a cusp and the cutting of a conventional preparation with an occlusal lock. Group A were restored with amalgam only, Group B with amalgam and a pin, Group C with amalgam and Amalgambond (4-META) and Group D with amalgam, a pin and Amalgambond. The teeth were blocked in stone and stored for 7 days in water at 37 degrees C. Using an Instron, a force was delivered at right angles to the inclined cuspal plane of the amalgam at its midcuspal point at a crosshead speed of 5 mm per minute. The load at failure was recorded and the assemblies recovered for fracture analysis using SEM. Group A failed at 33.61 +/- 15.17 Kg, Group B at 32.28 +/- 12.10 Kg, Group C at 48.53 +/- 21.93 Kg and Group D at 47.84 +/- 14.79 Kg. No statistically significant difference existed between Groups A and B, and Groups C and D. A significant difference (P < 0.002) existed between Groups A and C and B and D. Failure commonly occurred between cusp and occlusal lock or within the cusp when a pin was used. Bonded restorations with a pin incurred cohesive root failure. It was concluded that the strength of the amalgam restorations benefitted significantly from bonding but the Amalgambond system may be contraindicated for use with pins due to root fracture.

Periodontal considerations in the restoration of non-vital teeth.

Periodontal status is considered in relation to the construction of post core retained restorations. The surgical management of those problems apical to the gingival tissues is discussed in detail.

The relationship between Universal Dental Anchorage System (UDA) pins and the dental pulp chamber, in vitro.

PURPOSE OF STUDY: The Universal Dental Anchorage (UDA) System incorporates the use of pins inserted into enamel and dentine to retain a pontic. The pins are placed horizontally into teeth in the region of the contact area and so are potentially placed close to the dental pulp. This study aims to investigate and measure this relationship to assess if the pulp may be placed at risk during pin hole preparation or UDA pin placement. METHODS: Teeth were assessed radiographically and pins placed according to manufacturer's instructions. The teeth were subsequently sectioned through the pin position and measurements from the pin tip to the pulp chamber made at 4X magnification. RESULTS: In the majority of the teeth the pins were in close proximity to the pulp chamber (mean +/- sd = 0.8 +/- 0.7 mm). Two pins were in direct communication with the pulp chamber. Seven pins were separated from the pulp chamber by only 0.1-0.5 mm and six pins by 0.6-1.0 mm. Three pins were more than 1.0 mm from the pulp chamber. CONCLUSION: The results suggest that the use of 2.1 mm UDA pins would, in many cases, represent a risk to pulpal health.

[The prevention of complications from the use of cast stump pin inserts for the fixation of metal-ceramic dentures]. / Profilaktika oslozhnenii pri primenenii litykh kul'tevykh shtiftovykh vkladok dlia fiksatsii metallokeramicheskikh protezov.

A total of 186 patients aged 18 to 69 years with complications caused by metalloceramic dentures fixed on pulp-extracted teeth were studied. Major complications were: gingival retraction--21 teeth (9.81%), inflammation of gingival margins--24 (11.2%), inflammation of mucosa underlying the denture--29 (13.54%), full fracture of dental crown--34 (15.89%), loosening of the metalloceramic dentures--82 (38.32%), splitting of a part of dental root wall--24 (11.22%). The causes of the above complications were analyzed and preventive measures outlined.

[The principles of designing stump pin inserts in pathological tooth abrasion]. / Printsipy konstruirovaniia kul'tevykh shtiftovykh vkladok pri patologicheskoi stiraemosti zubov.

A total of 278 patients aged 40 to 67 with pathological abrasion of hard dental tissues were treated. Decreased occlusion height was diagnosed in 152 (54.67%) of these. In 146 patients abutment teeth under permanent dentures were fixed with cast stump pin insertions. Complications occurred in 9.6% cases: perforation of the wall of the root canal (1.14%), failure of cementing (3.98%), fracture of the root (1.14%), breaking of a fragment of the root at the neck of the tooth (2.84%), and inflammations of the marginal periodontium (0.57%). In order to prevent these complications and improve the fixation of cast stump pin insertion, we used our modifications of cast stump pin insertions (n = 394) for anterior and lateral teeth. The incidence of complications decreased more than 5 times. Follow-up of 2 to 8 years showed 1.78% of complications.